How flexible is VGPs' avoidance of exogenous capture? Is it an all or nothing capacity, or can there be more graded control over exogenous attention? To address these questions we employ an *anti-cueing paradigm* (Experiment 1). In a typical spatial cuing task, there are specific locations where targets could appear and one of those locations is cued prior to target onset, generating exogenous capture. In target-cued conditions, the cue indicates the likely position of the target. In an anti-cueing paradigm, the appearance of the cue in one location actually indicates that a target will likely appear in a different location (Posner et al., 1982; Warner et al., 1990; Prinzmetal et al., 2009). For example, if the right location is cued (see **Figure 1**), there is a high probability that the target would appear on the left. Thus, the information given by the cue is task-relevant, but the spatial location of the cue is not the to-be-attended location. If VGPs can resist exogenous capture by this stimulus, but still use the information it provides in order to endogenously shift their attention, it would imply very precise control over attention.

In Experiment 2 we address the question of visual speed of processing using an attentional blink (AB) task. It has been argued that VGPs may process visual stimuli more quickly than nVGPs (e.g., Wilms et al., 2013). But is this faster apprehension related to overall processing-speed differences between VGPs and nVGPs? Might it even be associated with greater sensitivity to distractors (e.g., West et al., 2008)? If so, this could pose a problem for interpreting results showing reduced exogenous capture for VGPs, as attending to a stimulus and then very rapidly processing and disengaging from it may have the same behavioral effect as avoiding attentional capture at certain timescales.

To preview our results, we found superior control over exogenous attention in VGPs compared with nVGPs, but no differences between groups in endogenous attention or speed of processing.

# **EXPERIMENT 1 – ANTI-CUE**

In the anti-cue task, a cue is presented at one spatial location, but indicates that the target is likely to appear in a specific other location. This allows for the separation of the effects of exogenous

darken. After either 40 or 600 ms, the stimulus array would appear and participants would report whether a "T" or an "F" was present.

attention and endogenous attention, a difference that should be more apparent in response time (RT) than in accuracy (Prinzmetal et al., 2009). If the sudden-onset of the cue exogenously captures attention, then when the interval between the cue and the target is short, participants should be faster to respond to those rare targets that appear at the location of the cue than those targets that appear in the more likely, anti-cued location. Conversely, when the interval between the cue and the target onset is longer, then participants will have sufficient time to endogenously move their attention to the likely target location, providing an advantage at the anti-cued location compared to the location of the cue. This design allows for separate assessments of the relative exogenous and endogenous attentional performance of VGPs and non-players.

#### **METHODS**

#### *Participants*

Forty-two members of the University of California, Berkeley community participated in exchange for a cash payment or partial fulfillment of a course requirement. Other data from a subset of these participants that were collected in the same experimental session have been reported previously (Cain et al., 2012). Participants were recruited using a variety of methods including poster advertisements specifically seeking first-person shooting (FPS) game players and non-players and e-mail advertisements selectively sent to those with high and low levels of reported FPS expertise in a prescreening survey. Participants were not informed which survey in the prescreening packet lead to their recruitment until the end of the study.

Data from two participants were excluded, one for not completing the experiment and another for performing at chance-level accuracy throughout the experiment. The remaining 40 participants were classified into two groups based on their self-reported expertise and experience with action video games. The VGP group reported expertise with FPS video games of ≥5 on a 1–7 scale and regular play of FPS games (≥5 hr/wk) in the last 6 months. The VGP group consisted of 17 males and two females (mean age = 21.0 years). The non-player (nVGP) group reported expertise with FPS games of ≤2 on a 1–7 scale and recent experience with FPS games of <2 hr/wk in the last 6 months. Note that expertise or experience with other genres of video games (e.g., puzzle games) was not cause for exclusion from the nVGP group. The nVGP group consisted of eight males and 13 females (mean age = 22.5 years).

#### *Stimuli*

Four peripheral boxes and a central fixation dot were present on the screen throughout the experiment (see **Figure 1**). Each box extended approximately 2.0◦ × 1.25◦ and was 1 pixel thick. The innermost edge of each box was 1◦ from fixation. The fixation dot was a solid black circle 0.1◦ in diameter.

On each trial the cue was a thickening of the outline of one of the boxes to 0.1◦ wide. This thickened box remained visible until the stimulus array disappeared. The stimulus array included three characters per frame in a 36-point sans-serif font. The target letter was a "T" or an "F" and was always at the center of its array. All other placeholder letters in the display were "O".

#### *Procedure*

The procedure is identical to that in Prinzmetal et al. (2009, Experiment 3). Participants were instructed to maintain fixation at all times during each trial. Fixation was monitored online using a video camera with a researcher labeling trials in which fixation was broken as they occurred. Eye movement trials were re-run at the end of the block in which they occurred.

On each trial a cue gave participants information about the likely position of the target. On 75% of trials the target appeared in the box opposite the cue (anti-cued location). On 12.5% of trials the target appeared in the same location as the cue (cued location). On the remaining 12.5% of trials the target appeared in one of the two off-axis boxes (other location); these catch trials were not included in any of the planned comparisons. Participants were informed that the target was "most likely" to appear in the anti-cued location, but could appear in any location. Participants were not given explicit probabilities.

The stimulus array appeared after the cue at one of two randomly intermixed stimulus onset asynchronies (SOAs). The Short SOA (40 ms) was intended to generate exogenous attention capture: participants should have had their attention drawn to the sudden-onset cue, but should not have had time to endogenously move their attention to the likely target (i.e., anti-cued) location. The Long SOA (600 ms) was intended to allow time for endogenous movement of attention from the cued location to the anti-cued location. The stimulus array remained on the screen for 120 ms (to minimize the utility of eye movements) at which time both the stimuli and cue disappeared. After the stimuli disappeared, participants responded whether a "T" or an "F" was present with a speeded keypress of the "1" and "2" keys on a numeric keypad using the index and middle fingers of their right hand.

Trials were presented in seven blocks, separated with self-paced breaks. The first block was 48 trials long, considered practice, and not analyzed. The six experimental blocks were each 96 trials long. Throughout the experiment, auditory feedback was given for incorrect responses and eye movements.

# **RESULTS**

Data from trials with RTs < 150 ms or > 1580 ms (three standard deviations above the mean RT for all correct trials) were excluded from analysis (0.9% of experimental trials). Analyses were conducted in parallel for both accuracy and RT (see **Table 1** for a full breakdown), with incorrect trials excluded from RT analysis. Data from the Other Location catch trials were not analyzed, but are reported in **Figure 2** and **Table 1** for comparison purposes.

# *Overall analysis*

Results were primarily analyzed with linear mixed effects models (Baayen et al., 2008; Barr et al., 2013) using the lme4 package in R (Bates et al., 2013). These models are similar to repeatedmeasures ANOVAs, but use all experimental trials rather than averages and allow for better testing of proportional data (i.e., accuracy). For both accuracy and RT, models were constructed with Group (VGP or nVGP), Target Position (Cued or Anti-Cued), and SOA (40 or 600 ms) as fixed effects and Participant as a random effect. For accuracy, a logistic model that included a three-way Group × Target Position × SOA interaction fit the data significantly better than a model in which the Target × SOA interaction did not interact with Group [χ2(3) = 9.14, *p* = 0.0275]. Similarly for RT, a model that included a three-way Group × Target Position×SOA interaction fit the data significantly better than a model in which the Target × SOA interaction did not interact with Group [χ2(3) = 14.41, *p* = 0.0024]. To better understand how exogenous attentional capture varied between groups, we performed further analyses separately for each SOA. To preview, there was an interaction between Group and Target Position for RT, but not accuracy, in the Short SOA condition, and an interaction for accuracy, but not RT in the Long SOA condition.

#### *Short SOA condition*

Results for the Short SOA condition were analyzed using linear mixed effects models with Group and Target Position as fixed effects and Participant as a random effect. Accuracy was uniformly high and there was no difference between a logistic model that included a Group × Target Position interaction and one that did not [χ2(1) = 0.25, *p* = 0.6170]. RT results are summarized in **Figure 2A** and, unlike accuracy, showed evidence of a Group × Target Position interaction [χ2(1) = 4.73, *p* = 0.0296], implying that there are attentional cuing RT differences between groups. To understand the nature of this interaction, we performed *post hoc* paired-samples *t*-tests within each group. Consistent with previous findings, nVGPs were faster to respond when the

**Table 1 | Breakdown of means and standard deviations (SDs) of accuracy and response time (RT) measures across all groups and conditions.**

*SOA, stimulus onset asynchrony; VGP, video game player; nVGP, non-video game player.*

target was at the cued location than at the anti-cued location [*t*(20) = 3.054, *p* = 0.006, Cohen's *d* = 0.217]. However, VGPs were just as fast to respond to the target at the anti-cued location as at the cued location [*t*(18) = 0.417, *p* = 0.681, *d* = 0.030], suggesting reduced or eliminated exogenous attentional capture.

#### *Long SOA condition*

Results for the Long SOA condition were analyzed using the same linear mixed effects models as in the Short SOA condition. For accuracy, in contrast to the Short SOA condition, there was evidence of a Group × Target Position interaction [χ2(1) = 8.69, *p* = 0.0032]. To understand the nature of this interaction, we performed *post hoc* paired-samples *t*-tests on arcsine-squareroot-transformed accuracy within each group. VGPs were more accurate when responding to targets at the anti-cued location and nVGPs were more accurate at responding to targets at the cued location, but neither of these individual comparisons was statistically significant (both *p* > 0.4). RT results are shown in **Figure 2B**. Unlike the Short SOA condition, there was no evidence of an interaction between Group and Target Position [χ2(1) = 0.08, *p* = 0.7813]. *Post hoc* paired-samples *t*-tests revealed that both groups showed significant cuing effects [VGPs: *t*(18) = 2.467, *p* = 0.024, *d* = 0.415; nVGPs: *t*(20) = 3.234, *p* = 0.004, *d* = 0.259].

#### **DISCUSSION**

VGPs were better at resisting exogenous attentional capture by a suddenly appearing cue, but were just as able to use the information from the cue to endogenously direct their attention to a likely target location. Unlike the nVGP group, which demonstrated normal levels of attentional capture in the Short SOA condition, the VGP group performed equivalently quickly at all locations in the Short SOA condition. Importantly, in the Long SOA condition, the VGP group was able to use the cue to direct their attention to the probable target location, demonstrating the expected anti-cueing effect. Thus, theVGP group was not ignoring the task-relevant cue, but was able to suppress exogenous capture from its onset. Interestingly, a similar pattern of results has previously been shown with training on the anti-cue task (Warner et al., 1990), suggesting that general action video game experience may have a similar effect on underlying attentional mechanisms as specific task training.

There is an alternative explanation for the current results that bears consideration. It has been suggested that VGPs may enjoy a speed of processing advantage over nVGPs (Dye et al., 2009; Wilms et al., 2013). Perhaps the VGPs were experiencing just as much exogenous capture as the nVGPs, but were able to very rapidly process the cue, such that they were no longer captured by it when the target array appeared, even in the Short SOA condition. We address this speed of processing question in Experiment 2.

#### **EXPERIMENT2–ATTENTIONAL BLINK**

Could the apparent resistance to exogenous capture seen in Experiment 1 be the result of faster processing of the cue stimulus? A few lines of evidence support this hypothesis. The most general claim is from a meta-analysis of VGP vs. nVGP studies that found that overall, VGPs perform faster than nVGPs with no loss in accuracy (Dye et al., 2009). This improvement could have come from increased speed of visual processing or from later stages such as decision processes, response execution, or some combination thereof. Other studies have demonstrated that VGPs are quicker to get information into visual working memory than nVGPs (Appelbaum et al., 2013) and are faster to accumulate visual evidence from noisy visual stimuli (Green et al., 2010). This suggests there may be a visual processing advantage for VGPs, but it's not clear if this advantage would also apply to simpler situations like suddenonsets. Most directly, one recent study specifically found faster visual processing forVGPs in a modified whole-report task (Wilms et al., 2013).

If faster visual processing in VGPs, lead to faster processing of the cue in Experiment 1, we might also expect faster processing of stimuli presented in quick succession in a rapid serial visual presentation task. In particular, VGPs would be expected to have a reduced *AB* (Raymond et al., 1992). The AB is a phenomenon where processing of one target item impairs processing of a second item encountered 200–500 ms later. This deficit is believed to be due to a processing bottleneck in which the second target cannot be processed simultaneously with the first target (see Martens and Wyble, 2010 for a review). If VGPs are faster at processing rapidly presented items, they may be able to more completely process the first target before the second appears, reducing the impact of this bottleneck and, thus, reducing the AB. Several previous studies suggest that VGPs have a reduced AB compared to nVGPs (e.g., Green and Bavelier, 2003; Oei and Patterson, 2013), though there is not complete agreement on this point (Boot et al., 2008; Murphy and Spencer, 2009). Importantly, not all AB tasks are the same (e.g., Kelly and Dux, 2011). Previous studies have used forms of the AB paradigm that involve other factors, such as task switching and fast apprehension of stimuli – two abilities previously shown to be superior in VGPs (e.g., Cain et al., 2012; Appelbaum et al., 2013). Here, we attempt to minimize the contributions of these other factors to better examine the question of speed of processing.

# **METHODS**

#### *Participants*

Fifty-two members of the University of California, Berkeley community participated in exchange for a cash payment or partial fulfillment of a course requirement, including 34 individuals who also participated in Experiment 1 as part of the same testing session. Other data from some participants have been reported previously (Cain et al., 2012). Data from three participants were excluded, one for making > 25% incorrect responses to first targets, and two for having incomplete data. Participants were divided into VGP and nVGP groups using the same criteria as for Experiment 1. The VGP group had 23 members (22 males and one female; mean age = 20.9 years) and the nVGP group had 26 members (11 males and 15 females; mean age = 22.2 years).

#### *Stimuli and procedure*

Streams of letters (distractors) and numbers (targets) were presented at the center of the screen against a gray background (see **Figure 3**). Each trial's stream contained 12 items presented for 80 ms each with a 20 ms inter-stimulus-interval (i.e., 100 ms stimulus onset asynchrony). Distractor items were black letters. Every trial contained a single white number target (T1) and 77% of trials contained an additional black number target (T2) that could only appear after T1. The remaining 23% of trials were catch trials that had no second target. Relative to T1, T2 could appear at lags of 1 (immediately after), 2, 3, 5, or 7 items.

On each of the 156 experimental trials participants observed the stream of characters and then separately reported the identity of the two target numbers using a standard computer keyboard. Participants used the space key to indicate that they did not see a particular number. Responses were unspeeded and instructions emphasized accuracy.

#### **RESULTS**

Accuracy data were analyzed for T2 on trials on which T1 was correct. First, T2 accuracy data were submitted to a linear mixedmodel analysis with Lag (1, 2, 3, 5, or 7) and Group (VGP or nVGP) as fixed effects and Participant as a random effect. There was no evidence of an interaction between Group and Lag [χ2(4) = 4.6346, *p* = 0.3269]. Overall T2 accuracy was higher for nVGPs (92.4%) than VGPs (88.7%), but this Group difference was not statistically significant [χ2(5) = 6.4782, *p* = 0.2624]. As illustrated in **Figure 4**, this suggests that both groups experienced an AB, but that there were no differences between the groups. These models were followed up with *post hoc t*-tests comparing T2 performance between groups at each Lag and there were no significant differences at any point (all *p* > 0.05, uncorrected). There was no significant difference in T1 accuracy performance between groups [*t*(47) = 0.331, *p* = 0.743, *d* = 0.087].

VGPs at all lags. Error bars represent standard error of the mean.

# *Attentional blink magnitude*

While there were no significant overall differences in performance between VGPs and nVGPs on this task, and nVGPs numerically outperformed VGPs, we wanted to specifically check AB performance. For each participant we calculated two AB scores: (1) Lag 7 (asymptote) performance minus Lag 2 (blink) performance and (2) the average of Lag 5 and Lag 7 minus the average of Lag 2 and Lag 3. For the Lag 7 minus Lag 2 measure, there was a significant overall AB effect of 13.39% [*t*(48) = 5.702, *p* < 0.001, *d* = 0.815], but no significant difference between groups [*t*(47) = 0.629, *p* = 0.532, *d* = 0.179]. The same pattern was seen for the average of Lags 5 and 7 minus average of Lags 2 and 3 measure: significant AB [*t*(48) = 4.764, *p* < 0.001, *d* = 0.6804], but no significant difference between groups [*t*(47) = 0.416, *p* = 0.679, *d* = 0.1180]. For both measures, VGPs had a numerically larger AB than nVGPs. While non-significant, this is noteworthy because it is opposite from the predicted direction.

# **DISCUSSION**

The current experiment demonstrated a robust AB effect, but no differences in performance between VGPs and nVGPs. If anything, nVGPs outperformed VGPs, the opposite of what was predicted based on previous work. This suggests two key points (1) that improved anti-cue performance for VGPs in Experiment 1 was due to improved resistance to attentional capture, rather than faster processing of the cue stimulus and (2) that improved performance was not due to general effects such as motivation or knowledge that the study was about video gaming (cf. Boot et al., 2011).

The lack of a difference between VGPs and nVGPs on this task stands in contrast to several previous reports. In particular, it contrasts with the initial finding by Green and Bavelier (2003; replicated in Oei and Patterson, 2013). While both our task and that of Green and Bavelier (2003) are considered to be AB tasks, and all AB tasks have significant shared variability (Dale et al., 2013), there are important differences between AB tasks that tap into task switching abilities and those that do not (Kelly and Dux, 2011; Dale et al., 2013).

In the present experiment, participants searched for numbers among letters. This is a categorical AB task that requires no task switching, since both targets are numbers to be detected among letters (T1 white, T2 black serially following T1). However, in Green and Bavelier's (2003) experiment, participants had two different tasks to perform for the two embedded targets serially presented. First, they detected a white letter among black letters and then monitored for the presence or absence of an X. This probe-style AB task taps into task switching abilities as well as attentional selection abilities (Kelly and Dux, 2011). VGPs have been shown to switch between pairs of tasks on related stimuli more easily than nVGPs, including switching between letter and digit classification (Andrews and Murphy, 2006; Strobach et al., 2012), between global and local feature processing (Colzato et al., 2010), and between opposing stimulus-response rules (Cain et al., 2012). Thus, some of the video-game-related improvements in AB performance noted previously may have been due to superior task switching abilities in VGPs.

Additionally, in Green and Bavelier's (2003) task, stimuli were presented very briefly (15 ms) while ours were presented relatively longer (80 ms). This presentation time difference likely contributed to the higher accuracy levels in our paradigm. In the 15 ms presentation version, the need to perceive the item quickly may have given the VGPs a further advantage, as VGPs have higher visual sensitivity than nVGPs and are better able to initially encode rapidly presented information into visual sensory memory (Appelbaum et al., 2013; but see Blacker and Curby, 2013; Wilms et al., 2013).

Thus, the superior performance seen inAB tasks previously may be due, in part, to improved task switching and visual sensitivity in VGPs relative to nVGPs and not to factors more commonly associated with the AB, such as the speed of processing T1. This idea of more general performance improvement is reinforced by an examination of the results of Green and Bavelier (2003), which shows a VGP advantage across Lags 1–5, and not just at the critical AB Lags and a training benefit at only later lags. While the current null result can provide only limited evidence, in combination with prior work, it suggests that the exact parameters of the AB task may be crucial for finding differences between VGPs and nVGPs.

# **GENERAL DISCUSSION**

Here we demonstrated that action VGPs have greater resistance to exogenous attentional capture than those who do not play action video games. In Experiment 1, when the time between the cue and the target was long, both VGPs and nVGPs showed the expected anti-cueing effect, responding faster at the anti-cued location than the cued location. Hence both groups displayed equivalent ability to utilize the information provided by the cue (i.e., predicting the anti-cue target location). However, when the SOA was short, nVGPs showed the expected exogenous cuing effect, but VGPs did not: nVGPs were faster at the location of the cue than at the most likely, anti-cued location, but VGPs were equally fast at all locations. Hence, while clearly extracting the information provided by the cue (as evident in longer SOAs) VGPs were able to avoid being captured to that same cue location. In Experiment 2, the finding that there was no difference in AB performance between VGPs and nVGPs suggests that the cuing effects were not due to speed of visual processing or motivational differences between groups.

These results are in line with recent findings that VGPs resist attentional capture by task-irrelevant distractors (Chisholm et al., 2010; Chisholm and Kingstone, 2012). However, it is seemingly at odds with a previous cuing finding: In a modified temporalorder judgment task with uninformative cues, VGPs were more likely to be captured by the cue than nVGPs (West et al., 2008; Experiment 1). The key difference between that paradigm and ours may be the informativeness of the cue. In the West et al. (2008) task, targets always appeared in both locations and the appearance of the cue carried no information about the relative target timings. Thus, from a participant's point of view, attending to the cue had no noticeable effect on performance, so there was no particular reason to attempt to resist capture. In the current paradigm, the target only appeared in the cued location on 12.5% of trials, so being captured by the cued location might have noticeably negatively impacted performance, giving

participants an incentive to try and resist capture. Also, we explicitly instructed participants that the target would most likely not appear in the cued location, and it may be that the VGP group was better able to use this instructional information than the nVGP group.

Our results fill in an important gap in the existing literature on attentional capture in VGPs. Previous work has demonstrated that VGPs are captured by exogenous cues that aid in task execution (Hubert-Wallander et al., 2011b) or have a non-obvious negative impact (West et al., 2008) but are able to resist capture by exogenous distractors that obviously hindered performance (Chisholm et al., 2010; Chisholm and Kingstone, 2012). Here we presented task-relevant information at a to-be-ignored spatial location and demonstrated that VGPs were able to resist attentional capture to an irrelevant spatial location while still being able to use cue information from that location to help them on the task. Taken together these results suggest that VGPs may possess more flexible control over what does and does not capture their attention: When a stimulus facilitates performance, VGPs can get the full benefit of letting it capture their attention, but when it hinders performance VGPs can resist capture.

#### **RELATIONSHIP WITH OTHER VISUAL ATTENTION PHENOMENA**

One effect that has been much discussed in the video game literature is the flanker compatibility effect (i.e., distractor items surrounding a central target item speed responding if they are compatible with the target but slow responding if they are incompatible). If VGPs have better control over exogenous attention capture, this suggests that they might be less affected by the presence of incompatible flanking items in a display. In fact, initial reports argued that VGPs were actually more affected by incompatible flanking items than were nVGPs (Green and Bavelier, 2003, 2006a). However, subsequent reports have found equivalent levels of flanker interference in VGPs and nVGPs (Irons et al., 2011; Cain et al., 2012). While there is still some disagreement on this issue, it is clear that VGPs do not experience less flanker interference than nVGPs, which suggests some limits on their ability to control their attention. One potentially important difference between the cuing and flanker paradigms is the proportion of validly cued trials; in cases where VGPs have resisted stimulus capture, it was beneficial to do so most of the time, but in flanker experiments there is usually an even ratio of compatible trials (where capture helps) and incompatible trials (where it hinders), perhaps not providing sufficient incentive to exert control over exogenous capture. This line of argument suggests that studies manipulating cue validity may be able to more fully link these literatures.

Another attentional paradigm where VGPs have demonstrated benefits over nVGPs is multiple object tracking. In particular,VGPs are able to track more objects moving among distractors than nVGPs (Trick et al., 2005; Green and Bavelier, 2006b; Sungur and Boduroglu, 2012). This improved tracking performance is consistent with improved resistance to attentional capture: If VGPs are better able to resist capture by distracting items as those items pass near targets, this could lead to fewer instances where the target is lost. Unlike video game experience and training, specific spatial attention training does not lead to object tracking improvements

(Appelbaum et al., 2011). This implicates a separate mechanism for superior performance by VGPs, such as exogenous attentional control.

### **PROCEDURAL ISSUES**

There has been increasing dialog about the best practices for studying the cognitive effects of video game experience (e.g., Boot et al., 2011; Kristjánsson, 2013), with two central issues: training vs. expert designs and participant recruitment. In the present experiments, we compared novice VGPs with expert VGPs. This has the advantage that our expert population has a great deal of experience (our VGPs reported playing ≥ 130 h of FPS games in the previous 6 months, between 2 and 10 times more exposure than in a typical training study), giving us the opportunity to observe skills that may only emerge after a great deal of practice. It should be noted, however, that such a quasi-experimental design has the drawback that we cannot be sure that the effects we observe are directly due to video game experience and not some other factor such as a selection bias (e.g., individuals with better control over attentional capture may play more FPS games, if such control makes gameplay more enjoyable).

One persistent source selection bias is gender, as action video games tend to engage males more than females (e.g., Lucas and Sherry, 2004). The present groups are not balanced by gender and thus, it is possible that gender differences in attentional abilities might underlie our effects (e.g., Feng et al., 2007), or the choices of our participants to become VGPs or nVGPs. A reanalysis of the current dataset including only male participants yielded the same general pattern of results, but the reduced statistical power limits the interpretability of this reanalysis.While we consider large differences in expertise with action video games between groups to be a more parsimonious explanation of the current results than gender differences, the current results are unable to definitively resolve this question.

Participants in these experiments were recruited both from prescreening survey responses and from fliers explicitly seeking VGPs and nVGPs. The explicit recruitment of some participants opens the possibility that groups were differently motivated, for example those identifying as VGPs may have come into the experiment expecting to perform well, while nVGPs may have had lowered expectations (e.g., Boot et al., 2011). While we cannot fully rule out this possibility, the lack of group differences in the AB task in Experiment 2, performed in the same testing session as Experiment 1, suggests that the effects were not driven solely by global motivational differences (see Cain et al., 2012; Schubert and Strobach, 2012 for similar arguments).

# **CONCLUSION**

There is no clear consensus on exactly what cognitive abilities are trained by action video game play or how such play actually leads to the generalized learning that has been observed. However, new ideas are beginning to emerge for how to characterize fundamental cognitive improvements due to video games (e.g., Baniqued et al., 2013). It seems clear that there are likely a number of factors that video games train, such as faster visual apprehension (e.g., Appelbaum et al., 2013), improved cognitive control (e.g., Cain

et al., 2012; Strobach et al., 2012), and even the ability to quickly adapt within an experimental context (e.g.,West et al., 2013). Here we argue that the ability to control and focus attention on taskrelevant information is also a fundamental cognitive ability trained by video games. While the current study compared expert populations, and cannot speak directly about causality, one recent example more directly suggests a causal role. nVGPs were trained on custom FPS games that either required players to discriminate between hostile and friendly targets or contained exclusively hostile targets. Only those nVGPs in the target discrimination training condition showed attentional benefits from training (Brown et al., 2012).

The degree to which salient objects capture attention can vary from moment to moment (Leber, 2010). When acting in an uncertain visual environment, it would be advantageous to have flexible control over the level of exogenous attentional capture to a given location. Depending on the context, performance may be improved by allowing attention to be captured to a location by exogenous stimuli or by preventing capture. Action VGPs seem to be more adept than non-players at analyzing and adapting to the overall statistics of the visual task set at hand, likely due to extensive practice encountering, engaging with, and responding to the task demands of new environments in video games. In particular, the ability to extract information from a sudden-onset cue without allowing the cue to capture attention demonstrates a very high level of control over attention in VGPs.

### **AUTHOR CONTRIBUTIONS**

Matthew S. Cain and Ayelet N. Landau conceived of, executed, and analyzed both experiments. Matthew S. Cain wrote the manuscript. Arthur P. Shimamura and William Prinzmetal provided guidance and support. William Prinzmetal designed and programmed the task in Experiment 1.

#### **ACKNOWLEDGMENTS**

This study was supported by NIH Grant DA14110 and NSF Grant BCS-0745835 to Arthur P. Shimamura. Thanks to Bona Kang, Nola Klemfuss, Samuel Sakhai, Sadaf Sareshwala, Bailey Seymore, and Katharina Volkening for assistance with data collection.

#### **REFERENCES**

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

*Received: 08 October 2013; accepted: 18 January 2014; published online: 10 February 2014.*

*Citation: Cain MS, Prinzmetal W, Shimamura AP and Landau AN (2014) Improved control of exogenous attention in action video game players. Front. Psychol. 5:69. doi: 10.3389/fpsyg.2014.00069*

*This article was submitted to Cognition, a section of the journal Frontiers in Psychology. Copyright © 2014 Cain, Prinzmetal, Shimamura and Landau. This is an openaccess article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.*

# Gaming to see: action video gaming is associated with enhanced processing of masked stimuli

# *Carsten Pohl 1,2\*, Wilfried Kunde1, Thomas Ganz 3, Annette Conzelmann4, Paul Pauli 4 and Andrea Kiesel 1*

*1 Department of Psychology, Cognitive Psychology, University of Würzburg, Würzburg, Germany*

*2 Hospital for Psychiatry, Psychotherapy and Psychosomatic Medicine Lohr am Main, Lohr am Main, Germany*

*3 University of Applied Sciences Esslingen, Esslingen, Germany*

*4 Department of Psychology, Biological Psychology, Clinical Psychology and Psychotherapy, University of Würzburg, Würzburg, Germany*

#### *Edited by:*

*Walter R. Boot, Florida State University, USA*

#### *Reviewed by:*

*Walter R. Boot, Florida State University, USA Jason S. McCarley, Flinders University, Australia*

#### *\*Correspondence:*

*Carsten Pohl, Department of Psychology, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany e-mail<EMAIL_ADDRESS>
Recent research revealed that action video game players outperform non-players in a wide range of attentional, perceptual and cognitive tasks. Here we tested if expertise in action video games is related to differences regarding the potential of shortly presented stimuli to bias behavior. In a response priming paradigm, participants classified four animal pictures functioning as targets as being smaller or larger than a reference frame. Before each target, one of the same four animal pictures was presented as a masked prime to influence participants' responses in a congruent or incongruent way. Masked primes induced congruence effects, that is, faster responses for congruent compared to incongruent conditions, indicating processing of hardly visible primes. Results also suggested that action video game players showed a larger congruence effect than non-players for 20 ms primes, whereas there was no group difference for 60 ms primes. In addition, there was a tendency for action video game players to detect masked primes for some prime durations better than non-players. Thus, action video game expertise may be accompanied by faster and more efficient processing of shortly presented visual stimuli.

**Keywords: masked priming, action video gaming, unconscious processing, prime visibility, expertise**

# **INTRODUCTION**

Over the last three decades, public as well as scientific interest in action video gaming focused mainly on negative consequences such as video game addiction (e.g., Griffiths and Meredith, 2009) or promoting the likelihood of aggressive behavior (e.g., Anderson et al., 2003; Carnagey et al., 2007). While there is still a lively debate whether action video games do actually increase aggressive behavior or whether effects found in the laboratory can be transferred to account for aggressive behavior in real live (e.g., Anderson et al., 2010; Bushman et al., 2010; Ferguson and Kilburn, 2010; Ferguson et al., 2013), research in recent years has also revealed several positive side-effects of playing action video games on vision, perception, attention, and cognitive control.

In a series of studies, Green and Bavelier(2003; 2006a; 2006b; 2007; see Green et al., 2010a, for a review) compared action video game players and novices regarding their performance in many standard paradigms of cognitive psychology, like the flanker task, enumeration task, useful field of view task, attentional blink task, multiple object tracking task, perceptual load paradigm, and crowding paradigm. Compared to novices, action video game players performed better in peripheral and central vision tasks, better under dual task conditions, and action gamers displayed evidence of greater attentional resources, an enhanced spatial distribution of attention, and a greater temporal and spatial resolution of attention. Action video game usage also seems to promote parallel processing, as action video game players were able to enumerate and track substantially more items at once than novices (Green and Bavelier, 2006b; see also Trick et al., 2005). Further, action video game players also showed benefits for multisensory processing when visual and auditory stimuli were presented in close temporal succession (Donohue et al., 2010). Video game experience was also associated with an increased ability to switch between two tasks (Colzato et al., 2010), enhanced monitoring and updating of working memory (Colzato et al., 2013), and improved probabilistic inference (Green et al., 2010b). These tasks are considerably different from the situation of gaming itself which suggests a substantial transfer of training.

Moreover, training studies suggest that differences between gamers and non-gamers are not just correlational, but that there is a causal relationship between action video game play and improved perceptual and cognitive abilities (e.g., Green and Bavelier, 2003, 2006a,b, 2007; Li et al., 2009; Strohbach et al., 2012). Novices who were trained with an action video game (Medal of Honor, Call of Duty 2, or Unreal Tournament) performed better than novices who were trained with a nonaction video game (Tetris or The Sims). Ten to 50 h of training with an action game was sufficient to induce considerable impoverishments.

Regarding more basic effects on visual processing, Li et al. (2009) reported a long-lasting enhancement of contrast sensitivity through action video game playing and intensive training. Contrast sensitivity is "the ability to detect small increments in shades of gray on a uniform background" (Li et al., 2009, p. 549). It is seen as "one of the most basic visual functions that commonly deteriorate with aging" (Caplovitz and Kastner, 2009, p. 527) and it is assumed to be important in many different visual tasks. Contrast sensitivity was measured with a detection task for a briefly presented gabor patch. Detection performance was better in action video game players and action video game trained participants than for novices and non-action video game trained participants.

Furthermore, using a lateral masking paradigm, Li et al. (2010) found that action video game training also influences the temporal dynamics of vision. A central gabor patch was presented as target. This gabor patch was masked by two vertically flanking gabor patches. The SOA of the masks was varied in order to create forward or backward masking. Participants had to detect the central gabor patch. Action video game players showed reduced backward masking compared to non-action game players. This pattern of result was replicated in a training study, suggesting a causal relationship between action video gaming and improved cortical dynamics.

The aim of the current study is to further increase our knowledge of types of processes might be affected by video game expertise. Here, we asked whether action video game expertise enhances not just the ability to detect visible stimuli but also the ability to process stimuli that are hardly visible. To assess processing of such stimuli, we used a masked priming paradigm (e.g., Dehaene et al., 1998; Dell'Acqua and Grainger, 1999; Naccache and Dehaene, 2001; Kunde et al., 2003; Kiesel et al., 2006a) and assessed stimulus-response translation processing based on masked prime stimuli. In addition, we also assessed visibility of the masked stimuli in a visibility test.

There are two reasons for this approach. First, using masked stimuli helps to scrutinize the level of neural processing that action video gaming affects. The impact of masked stimuli is based on what Lamme calls the "forward sweep" of stimulus processing (Lamme, 2003, 2006). This relates to fast forward processing of retinal input within the first about 100 ms. Observers are not aware of stimuli at that level of processing, and normally do not become aware of them later, provided the visual representation is destroyed by masking. It is only when the visual percept is stabilized by recurrent neural processing that consciousness kicks in. Demonstrating that video gaming impacts the processing of masked stimuli would thus reveal that this impact occurs already at the first neural processing sweep, rather than at the level of later recurrent processing. A second reason relates to potential strategic influences on performance. Action video gamers might adapt performance according to demand characteristics, particularly so if they assume that game experience was a reason for choosing them as participants (cf. Boot et al., 2011; Kristjánsson, 2013). In other words gamers might make larger efforts for fast responding just because they consider themselves as a specific sample supposed to respond quickly. Whereas it is obviously possible to change responses to stimuli that are consciously discernible, it is far less obvious how to change the impact of prime stimuli that are hardly visible. In fact, with the pictorial stimulus material we used here, subliminal primes affect performance largely independent of response times to conscious targets (except perhaps for very slow responses)—a finding we will replicate here (Kiesel et al., 2009; Heinemann et al., 2010). So while gamers might try to speed up responding due to demand characteristics, this is unlikely to affect the congruency effects exerted by masked primes. Such congruency effects are thus a less demandcontaminated measure of visual processing than RTs to visible stimuli are, although demand effects that do not leave a trace in RT cannot ultimately be ruled out.

For this experiment we used a picture priming paradigm we had already established in our laboratory and that produced stable priming effects (Pohl et al., 2010). Participants saw pictures of animals that could be easily classified as being smaller or larger than a reference object. Prior to each target picture, one of the same four animal pictures is presented as prime. If this prime suggests the same response as the target (congruent), participants usually respond faster and less error-prone compared to when prime and target suggest different responses (incongruent). To reduce visibility of the prime stimuli, primes are presented very short and additionally they are masked by random dot masks (see **Figure 1**). Here in this study, we presented primes either for 20 or 60 ms to assess stimulus-response translation processes of hardly visible and more visible stimuli. If video game players (VGP) process hardly visible stimuli more efficiently than nonvideo game players (NVGP), we expect larger congruence effects for the players.

This design differs substantially from the lateral priming design Li et al. (2010) used. In their study, the correct temporal detection of a gabor patch was assessed. Participants had to decide in which of two intervals the gabor patch was presented. In contrast, in the present study, we were interested to find out whether action video gaming is associated with enhanced processing of masked primes in a way that affords processing of hardly visible stimuli according to their identity. In order to perform the task, participants had to identify the pictured animals and they were asked to categorize the pictured animals according their size in real life. Masked prime processing occurs when participants apply the task instructions already on the masked primes (cf. Dehaene et al., 1998). That would indicate that also masked animal pictures were processed in the same way as the clearly

affords the right response indicating "large."

visible targets, i.e., they are identified and categorized according to their size in real life.

In addition, participants performed a prime visibility test after the priming study. Here, primes were presented 20, 40, 60, 80, or 100 ms. This visibility test served two purposes. First, we wanted to check to which degree participants could see the primes. Second, we aimed to replicate the findings of Li et al. (2009) as well as Li et al. (2010) and expected that VGPs can identify the primes more often correctly than NVGPs.

#### **MATERIAL AND METHODS**

#### **PARTICIPANTS**

To recruit participants we placed two advertisements on a regional online job platform, one for people who play action video games (such as Call of Duty: Modern Warfare 3, Battlefield 3, Counter Strike, Boarderlands, or Medal of Honor) and one for people who play no computer games. Then we used the platform www*.*SoSciSurvey*.*de to identify a sufficient number of VGPs and NVGPs. The criteria for VGPs were that they indicated playing at least 8 to 10 h per week during the last year. NVGPs were persons who reported that they currently played no computer games and seldom did so in the past. Consequently, we conjecture that participants were aware that they were chosen for the experiment either because of their gaming experience or because of the lack of it.

We a priori decided to match the VGP and NVPG groups for age, gender, and IQ in order to guarantee that general cognitive abilities were equally distributed in both groups and both groups were consistent in terms of demographic makeup. Accordingly, from the 360 persons who participated in the online survey, we selected a sample of sixty healthy male adults between 18 and 29 years (with an average age of 23.7 years) who met either the criteria for VGPs (30 participants) or NVGPs (30 participants). They gave informed consent to participate in a study to investigate emotional, mental and behavioral processes. Data of five participants per group were not included in the analyses because afterwards they admitted that they did not fulfill the criteria for VGP (3 participants), declared to have a mental illness (1), or reported to have not followed the instruction in the prime visibility task correctly (4). Further, data of two participants of the NVGP group1 were discarded to ensure that the two groups did not differ with respect to intelligence. All participants reported having normal or corrected-to-normal vision, and were not familiar with the purpose of the experiment.

To check whether the VGP and the NVGP groups are similar expect for the gaming experience, we assessed fluid intelligence (via the SPM) as well as age. Intelligence was measured with a pen and pencil version of the Raven Standard Progressive Matrices Test (SPM; Heller et al., 1998) which was given without time limit. This test for fluid intelligence is widely used in research as well as in practice (Raven, 2000) for the measurement of general intelligence (reasoning ability of Spearman's g factor) and does not depend on language. For the analysis of fluid intelligence we calculated with the raw scores of the SPM because of missing current norms for the German sample (Heller et al., 1998). Independent samples *t*-tests showed no significant group differences for fluid intelligence, *t(*48*)* = 1*.*67, *p >* 0*.*10 and age, *t(*48*)* = −1*.*30, *p* = 0*.*20 (see **Table 1** for mean values).

#### **APPARATUS AND STIMULI**

The experiment took place in a dimly lit room. An IBM compatible computer with a 17 inch VGA-Display and the software package E-Prime™ (Schneider et al., 2002) were used for stimulus presentation and response sampling. Stimulus presentation was synchronized with the vertical retraces of a 100-Hz monitor, resulting in a refresh rate of 10 ms. Responses were executed with the index fingers of both hands and collected with an external keyboard with three response keys (1.7 cm width, distance 0.2 cm); the middle response key was not used.

The pictures used as targets and primes were derived from a set of gray scale shaded images of "Snodgrass and Vanderwartlike" objects (Rossion and Pourtois, 2004; see http://wiki*.*cnbc*.* cmu*.*edu/Objects) 2 . The target set consisted of four animal pictures (mouse, snail, lion and zebra,) that could be easily classified as being smaller or larger than a frame measuring 40 × 40 cm (mouse and snail—smaller; lion and zebra—larger). The same four pictures were used as primes. To vary visibility of the primes, primes were either presented for 20 ms or for 60 ms. All pictures were drawn in a white rectangle extending 2 cm high by 3 cm wide. Masks were random dot patterns extending 7.5 × 7.5 cm. They were constructed such that always 4 × 4 pixels were chosen randomly to be white or black. To increase masking, we presented always four different random dot patterns with a total duration of 80 ms as premask and four or two different random dot patterns with a total duration of 80 or 40 ms, respectively. Additionally, the prime as well as the target picture were also presented on a random dot pattern background (see **Figure 1**).

#### **PROCEDURE AND DESIGN**

The experiment was completed in a single session that lasted approximately 90 min and that was compensated with 12 Euro. The session consisted of two parts. First, participants executed a priming experiment. Second, a prime discrimination task was administered. Afterwards, individual intelligence was measured with the SPM.

In the following the two parts of the computer experiment are described in more detail.

#### **PRIMING EXPERIMENT**

The sequence of the events in a trial in the priming experiment is shown in **Figure 1**. On each trial, a fixation cross was presented for 400 ms. Then the premasks were presented for 80 ms followed by the prime presented either for 20 or 60 ms. Then the postmasks were presented either for 80 or 40 ms, respectively, so that the Simulus Onset Asynchrony (SOA) between prime and target presentation was always 100 ms. Finally, the target was presented

1These two participants revealed 36 and 37 points in the SPM, respectively. These scores are about 5 standard deviations below the mean scores and they are clear outliers because the next lowest SPM scores were 47 points in the NVGP group and 48 points in the VGP group, respectively.

2We thank Bruno Rossion and Gilles Pourtois who originally commissioned the pictures and Michael J. Tarr for making the pictures available.

**Table 1 | Mean values for demographic characteristics (standard deviations are given in brackets), performance for congruent and incongruent primes that were presented 20 and 60 ms, separately for VGPs and NVGPs (standard errors are given in brackets).**

directly after the postmasks for 250 ms. After response execution a fixed time interval of 1000 ms elapsed before the next trial started.

Participants were instructed to categorize the depicted animals as being smaller or larger than a reference frame (40 × 40 cm) and to respond as fast as possible while they should avoid to make errors. Participants had to press a left key with the left index finger to indicate "smaller" and a right key with the right index finger to indicate "larger" as fast and as accurately as possible. Errors were indicated by the German word for wrong ("Falsch!") presented in red in the lower part of the monitor. Response times were recorded from the onset of the target until the onset of the response.

There were 32 (4 × 4× 2) different combinations of target, prime and prime duration (20 or 60 ms) that were presented 10 times each. After each block of 64 trials, participants were allowed a short, self-paced break. In addition, mean response times and percentage of errors were fed back to encourage participants to increase their performance.

### **ASSESSMENT OF PRIME VISIBILITY**

After the priming experiment, we tested prime visibility with a separate prime discrimination task. In general, the stimuli as well as their sequence was comparable to the priming experiment. However, in this experimental part, participants were fully informed about the precise structure of a trial and the presence of the masked primes. This time, participants were asked to discriminate whether the prime picture was smaller or larger than the reference object. For the discrimination task, participants were instructed to take their time and to try to be as accurate as possible. In order to avoid that unconsciousness congruence effects influence the free response choice (see Schlaghecken and Eimer, 2004; Kiesel et al., 2006b), there was an interval of 800 ms after target offset, in which no response was possible (e.g., Vorberg et al., 2003).

In order to get a more graded assessment of prime visibility, we varied prime duration from 20 to 100 ms in steps of 20 ms. Thus, in a trial the prime picture was presented either for 20, 40, 60, 80 or 100 ms. As in the priming part of the experiment, the SOA was held constant for 100 ms. Therefore, postmasks were presented for 80, 60, 40, 20 ms, or were omitted, respectively. There were 80 (4 × 4× 5) different combinations of target, prime and prime duration (20, 40, 60, 80, and 100 ms) that were presented 5 times each leading to 400 trials altogether.

# **RESULTS**

### **PRIMING EXPERIMENT**

Trials with reaction times (RTs) deviating more than 2.5 standard deviations from the mean RT of each participant and each experimental condition (2.1%) were excluded.

Mean RTs for correct responses and error rates for each combination of the within-subjects factors prime duration (20 and 60 ms) and prime congruence (incongruent and congruent) for VGPs and NVGPs (between-subjects factor group) are given in **Table 1**. An analysis of variance (ANOVA) on RTs for correct responses with the between-subjects factor group and with the within subject factors prime duration and prime congruence, revealed significant main effects for all single factors: group, *F(*1*,* 48*)* = 6*.*6, *p* = 0*.*01, η2 *p* = 0*.*12, prime duration *F(*1*,* 48*)* = 94*.*2, *p <* 0*.*001, η2 *p* = 0*.*66, and prime congruence, *F(*1*,* 48*)* = 249*.*8, *p <* 0*.*001, η2 *p* = 0*.*84. On average VGPs responded faster than NVGPs (397 vs. 427 ms), participants responded faster after primes that were presented for 20 ms compared to primes that were presented for 60 ms (405 vs. 419 ms), and participants responded faster with congruent primes compared with incongruent primes (395 vs. 429 ms). The interaction prime duration × prime congruence was also significant, *F(*1*,* 48*)* = 254*.*7, *p <* 0*.*001, η2 *p* = 0*.*84. This significant interaction indicates that the congruence effect is larger for primes that were presented 60 ms than for primes that were presented 20 ms (57 vs. 11 ms). The interactions for prime duration × group and prime congruence × group were not significant, *ps* = 0.31. The three-way interaction of prime duration × prime congruence × group was marginally significant, *F(*1*,* 48*)* = 3*.*6, *p* = 0*.*06, η2 *p* = 0*.*97. The marginal three-way interaction was further explored in order to investigate whether the RT congruence effect differed in VGPs and NVGPs for the two prime durations. We analyzed the impact of 20 ms primes and 60 ms primes separately:

An ANOVA on RTs for correct responses after primes that were presented for 20 ms, with the between-subjects factor group and the within subjects factor prime congruence, revealed significant main effects for all single factors: group, *F(*1*,* 48*)* = 6*.*8, *p* = 0*.*01, η2 *p* = 0*.*13 and prime congruence, *F(*1*,* 48*)* = 27*.*4, *p <* 0*.*001, η2 *p* = 0*.*36. The interaction prime congruencex group was also significant, *F(*1*,* 48*)* = 5*.*8, *p* = 0*.*02, η2 *p* = 0*.*11, indicating that the congruence effect for VGPs was larger than for NVGPs (16 vs. 6 ms). Single comparisons show a significant congruence effect for VGPs, *t(*24*)* = 7*.*3, *p <* 0*.*001, and a marginally significant congruence effect for NVGPs *t(*24*)* = 1*.*7, *p* = 0*.*06.

On average VGPs responded faster than NVGPs. This was also true for primes that were only presented 20 ms (389 vs. 420 ms). To rule out that the difference in the RT levels was responsible for the difference in the congruence effects between VGPs and NVGPs, we examined RT distributions on the basis of percentile values obtained for each participant. For this we rank-ordered RTs per conditions in the 10% fastest, 10–20%,..., 80–90% RTs3 , computed the average RT per percentile and condition, and computed the congruence effect per percentile by subtracting RT incongruent—RT congruent per percentile. In **Figure 2**, the congruence effects per percentiles for NVGPs and VPGs are depicted depending on the mean RT of this percentile. The congruence effect for VGPs is rather constant over the percentiles and differences in the size of congruence effects for VGPs and NVGPs occur at similar RT levels.

An ANOVA on RTs for correct responses after primes that were presented for 60 ms, with the between-subjects factor group and the within subjects factor prime congruence, revealed significant main effects for the single factors group, *F(*1*,* 48*)* = 6*.*2, *p* = 0*.*02, η2 *p* = 0*.*12 and prime congruence, *F(*1*,* 48*)* = 355*.*0, *p <* 0*.*001, η2 *p* = 0*.*88. However, the interaction group × congruence was not significant, *ps >* 0*.*84, indicating that the congruence effect for VGPs did not differ for VGPs and for NVGPs (56 vs. 57 ms).

The overall mean error rate was 4.6%. The same ANOVA on error rates for all responses, revealed significant main effects for the within-subjects factors prime duration *F(*1*,* 48*)* = 54*.*3, *p <* 0*.*001, η2 *p* = 0*.*53, and prime congruence, *F(*1*,* 48*)* = 50*.*1, *p <* 0*.*001, η2 *p* = 0*.*51. Participants made more errors after primes that were presented for 60 ms compared to primes that were presented for 20 ms (6.4 vs. 3.3%) and participants made more errors after incongruent primes compared to congruent primes

3The percentile 90–100% contains too many outliers and is thus not considered.

(7.1 vs. 2.6%). The interaction prime duration × prime congruence was also significant, *F(*1*,* 48*)* = 30*.*6, *p <* 0*.*001, η2 *p* = 0*.*39. The congruence effect was larger for primes that were presented 60 ms than for primes that were presented 20 ms (7.7 vs. 1.3%). The between-subjects factor group was not significant, as well as the interactions for prime duration × group, prime congruence × group, and prime duration × prime congruence × group, *ps* = 0.36.

#### **PRIME VISIBILITY**

To assess prime visibility, we computed the signal detection measure *d*- . Prime pictures requiring the response "small" (animal) were treated as signal, whereas prime pictures requiring the response "large" (animal) were considered as noise. Hits and false alarms proportion of zero or one were corrected according to the log-linear rule (Goodman, 1970; cited according to Hautus, 1995) if participants had 0% hits or 100% false alarms. Prime visibility was above chance level for each group and prime duration: Separately for the different prime durations the discrimination performance for VGPs was for primes that were presented 20 ms *d*- = 0*.*53, *t(*24*)* = 6*.*80, *p <* 0*.*001, for primes that were presented 40 ms *d*- = 2*.*09, *t(*24*)* = 14*.*43, *p <* 0*.*001, primes that were presented 60 ms *d*- = 2*.*55, *t(*24*)* = 16*.*98, *p <* 0*.*001, for primes that were presented 80 ms *d*- = 2*.*63, *t(*24*)* = 18*.*47, *p <* 0*.*001, and for primes that were presented 100 ms *d*- = 2*.*75, *t(*24*)* = 19*.*07, *p <* 0*.*001 (see **Figure 3**). For NVGPs the discrimination performance for the different prime durations was for primes that were presented 20 ms *d*- = 0*.*33, *t(*24*)* = 3*.*95, *p <* 0*.*001, for primes that were presented 40 ms *d*- = 1*.*74, *t(*24*)* = 10*.*05, *p <* 0*.*001, for primes that were presented 60 ms *d*- = 2*.*11, *t(*24*)* = 12*.*28, *p <* 0*.*001, for primes that were presented 80 ms *d*- = 2*.*44, *t(*24*)* = 11*.*10, *p <* 0*.*001, and for primes that were presented 100 ms *d*-= 2*.*54, *t(*24*)* = 13*.*33, *p <* 0*.*001 (see **Figure 3**).

An ANOVA with the between-subjects factor group (VGPs and NVGPs) and with the within subject factor prime duration(20, 40, 60, 80, and 100 ms) showed that prime duration had a significant effect on prime visibility, *F(*4 *,*192*)* = 179*.*0, *p <* 0*.*001, η²= 0.78, whereas the factor group and the interaction group × prime duration were not significant, *ps >* 0*.*13. However, when only the prime durations are analyzed that were used in the priming experiment, then an ANOVA with the between-subjects

factor group (VGPs and NVGPs) and with the within subject factor prime duration (20 and 60 ms) revealed again that prime duration significantly effected prime visibility, *F(*1*,* 48*)* = 355*.*4, *p <* 0*.*001, η²= 0.88, as well as a significant effect for the factor group, *F(*1*,* 48*)* = 4*.*5, *p* = 0*.*038, η²= 0.09, providing at least some evidence that VGPs could discriminate the primes better than NVGPs at these two prime durations. The interaction group × prime duration remained insignificant, *ps* = 0.22.

#### **CORRELATIONS OF CONGRUENCE EFFECT, PRIME VISIBILITY, AND GAME EXPERIENCE**

Prime pictures that were presented for 20 ms, elicited a larger congruence effect in VGPs than in NVGPs, while prime visibility was higher in VGPs than in NVGPs when only the two prime durations of the priming experiment (20 and 60 ms) are considered. We therefore ran additional analyses in order to investigate how the two results (congruence effect and prime visibility) as well as video game experience are interrelated.

To test whether the congruence effect is related to the prime visibility, a regression analysis as proposed by Draine and Greenwald (1998, see also Greenwald et al., 1995, 1996) was computed. A priming index was calculated for each participant and each prime type, with index = 100 × (RT incongruent—RT congruent) / RT congruent. The indirect effects of individual priming indices were regressed onto the direct effects of individual *d* values separately for VGPs and NVGPs. Following this methodological approach a significant slope of the regression would indicate that congruency effects rise with increasing prime visibility, whereas the "regression intercept estimates the magnitude of priming associated with zero perceptibility of the prime" (Greenwald et al., 1996, p. 1700).

The linear regression analysis revealed no significant correlation between *d* and the priming index for prime pictures that were presented 20 ms, neither for VGPs with *r* = 0*.*105, *p* = 0*.*62, nor for NVGPs with *r* = 0*.*294, *p* = 0*.*15. A *post-hoc* Bayes test for correlations using the procedure of Wetzels and Wagenmakers (2012)revealed Bayes factors of 0.17 for VGPs and 0.42 for NVGPs modestly favoring the null hypothesis that the size of the congruency effects and prime visibility are not related to each other. The intercept of the regression was larger than zero for VGPs, intercept = 3.76, *t(*24*)* = 3*.*58, *p <* 0*.*01, indicating that significant congruence effect for 20 ms in VGPS can be expected even at zero visibility in terms of *d*- . In contrast there was no significant intercept for NVGPs, intercept = 0.85, *p* = 0*.*40.

For prime pictures that were presented 60 ms, the linear regression analysis revealed again no significant correlation between *d*- and the priming index for prime pictures, neither for VGPs with *r* = 0*.*100, *p* = 0*.*63, nor for NVGPs with *r* = 0*.*160, *p* = 0*.*45. A *post-hoc* Bayes test for correlations using the procedure of Wetzels and Wagenmakers (2012) revealed Bayes factors of 0.17 for VGPs and 0.21 for NVGPs modestly favoring the null hypothesis for VGPs and NVGPs, indicating again that the size of the congruency effects and prime visibility are not related to each other. Here the intercept could not be interpreted because *d* was *>* 0 for all participants. Thus, the observed congruence effect that is related to zero visibility for primes that were presented 20 ms is reliable for VGPs and independent on individual prime visibility. For primes that were presented 60 ms, the congruence effect is no longer related to null visibility, but it is still independent of individual prime visibility.

Although we found no significant correlation between individual prime visibility and the priming index in VGPs for primes that were presented for 20 ms, it is conceivable that the effect of video game experience on 20 ms prime processing was nonetheless mediated by an enhanced prime visibility. To rule out that differences in prime visibility are the driving force for increased priming effects in VGPs compared to NVPGs we conducted *post-hoc* a partial regression analysis of the variables game experience (the value was set 0 for NVGPs and 1 for VGPs) and priming index considering prime visibility (*d*- ) as confounding effect. A multiple regression with game experience and individual prime visibility as predictors and individual priming index as criterion revealed a significant correlation (*r* = 0*.*389, *p* = 0*.*021). Importantly, the correlation was also significant, when partialling the factor prime visibility (*r* = 0*.*286, *p* = 0*.*046), but not when partialling the factor game (*r* = 2*.*15, *p* = 0*.*137). These results indicate that prime visibility as possible mediator cannot completely account for priming effect differences between gamers and non-gamers with 20 ms primes. Instead, data suggest that game experience is directly related to the size of the congruency effects when prime visibility is controlled for.

# **DISCUSSION**

We compared video game players' (VGPs) and non-video game players' (NVGPs) ability to process shortly presented near threshold-stimuli in a response priming experiment using masked pictures of drawn animals. Reaction times were faster for VGPs than NVGPs. For primes that were presented only 20 ms, VGPs showed a larger prime congruence effect than NVGPs. For primes that were presented 60 ms, both groups showed a substantial congruence effect that did not differ for VGPs and NVGPs. Additionally, an exploratory analysis gives tentative evidence that VGPs detected masked primes that were presented 20 ms as well as 60 ms better than NVGPs (please note, however, that the improved detection performance is restricted to the prime durations applied in the priming experiment and does not generally hold true). Thus, it seems that gaming expertise is accompanied by more efficient stimulus-response translation and tentatively a somewhat improved visual identification of shortly presented visual stimuli. Apparently, video gaming speeds up already the initial neural processing stream, the so called forward sweep, before recurrent neural processing comes in. Cognitive models of stimulus-response translation have assumed two stimulusresponse-translation processes, one "response activation" process whereby stimuli automatically activate assigned motor responses, and another "response selection" process, that eventually determines whether activated responses are carried out (Hommel, 1998; Lien and Proctor, 2002). The masked priming effects we studied here are likely mediated by the fast response activation process (Schubert et al., 2008). Hence, gaming expertise conceivably improves the response activation process involved in the present priming task. However, because of the applied correlational design, some inconclusive findings, and due to further differential results between both groups there are a few caveats that have to be considered firstly.

First, VGPs responded on average 30 ms faster than NVGPs, reflecting a general RT advantage of video gaming experts (e.g., Green and Bavelier, 2003; Castel et al., 2005; Bialystok, 2006; Dye et al., 2009; Colzato et al., 2013). In a meta-analysis Dye et al. (2009) showed that VGPs are on average 11% faster than NVGPs whereby no speed accuracy trade-off occurred. In the present experiment VGPs were on average 8% faster than NVGs fitting well to the data of the meta-analysis (Dye et al., 2009). Similarly, overall error rates were numerically increased for VGPs compared to NVGPs and we thus cannot rule out speed accuracy trade-off. Indeed, a *post-hoc* Bayes test (http://pcl*.*missouri*.*edu/ bf-two-sample) of the main difference of RTs and error rates for VGPs and NVGPs revealed Bayes factors of 0.28 for RTs and 3.56 for errors (Rouder et al., 2009).

More importantly, however, overall faster RTs for VGPs than NVGPs might be the reason for congruence effects differences because prime impact is rather short-lived. For example, Greenwald et al. (1996) showed that masked priming effects decrease rapidly when the SOA between prime and target is longer than 100 ms. A concomitant percentile analysis ruled out this suspicion. It revealed a quite constant congruence effect for VGPs for all percentiles as well as different congruence effects for VGPs and NVGPs at similar RT levels (see **Figure 2**). Thus the different congruence effects for primes that were presented for 20 ms cannot be explained by the general effect of faster responses for VGPs than for NVGPs.

Second, there is mixed evidence whether or not the larger congruency effect for VGPs compared to NVGPs for primes that were presented 20 ms is related to increased prime visibility of VGPs. In some studies, it has already been demonstrated that congruence effects increase with prime visibility (Greenwald et al., 1996; Kunde et al., 2005). The present experiment somewhat replicates this result because in both groups of participants, primes that were presented for 60 ms elicited larger congruence effects and were better discriminable than primes that were presented for 20 ms. Please note however, that here prime duration is confounded with visibility. Yet, when just considering primes that were presented for 20 and 60 ms, we found a somewhat better prime discrimination performance for VGPs than for NVGPs. To further investigate whether the size of congruence effects for primes that were presented for 20 ms and prime discrimination are related to each other we conducted two additional analyses. On the one hand, regression analyses as well as *post-hoc* Bayes tests for VGPs and NVGPs respectively, suggested that larger congruence effects were not exclusively brought by a higher individual prime visibility. Moreover, a *post-hoc* test indicated that primes that were presented for 60 ms were also better discriminated by VGPs than by NVGPs, although the amount of congruence effects was equal in both groups. On the other hand, a partial correlation analysis controlling for indirect mediation through prime visibility showed that the direct effect of video gaming expertise on the congruence effect for primes that were presented 20 ms was not driven fully by a possible indirect effect of prime visibility. Thus, in the present experiment it seems that video gaming expertise is related to more efficient stimulus-response translation.

Third, regarding prime visibility we found no statistically significant advantage for VGPs compared to NVGPs in the omnibus test of the discrimination task with prime durations ranging from 20 to 100 ms (in 20 ms steps). This is probably because for long prime durations prime detection rates were quite high and might have been insensitive for group differences. However, this explanation is post hoc and has therefore to be treated cautiously. The same holds true for restricting the analysis to the two prime durations used in the priming experiment. When only these two prime durations (20 and 60 ms) were considered in an explanatory analysis results revealed better visual discrimination performance of masked stimuli for VGPs compared to NVGPs. This result is in line with a study of Li et al. (2010) which shows that action video gaming decreases the efficiency of backwards masks. Moreover with masked letter primes it has already been shown that discrimination performance was better for typing experts than for novices (Heinemann et al., 2010). Nevertheless, additional studies may be required to provide more definitive conclusions about possible video game expertise related detection improvements of shortly presented masked primes and to tease out the underlying mechanisms.

Fourth, a problem when comparing experts and novices refers to a placebo-like effect of expectation and motivation (Boot et al., 2011). It might be that based on how participants are recruited, they already expect that their status of expertise shall be investigated and are therefore more eager to show a good performance. In the present study, we selected participants based on their selfreported gaming experience, thus it might be that VGPs were more motivated than NVPGs eventually explaining the observed RT differences and the better prime discriminability of VGPs compared to NVGPs. Yet, for the congruence effect in the masked priming paradigm such biases hardly play a role. During the priming task, participants are hardly aware of the primes that were presented for 20 ms and it is thus not possible to strategically influence the priming effects. This assumption is supported by the finding that primes affected performance largely independent of response times to conscious targets. Our participants also reported no application of reasonable strategies in the priming experiment. (Occasionally methods such as trying to avoid errors or concentrating on probabilities of targets were reported. Yet, this latter strategy is not helpful as primes and targets occurred equally frequent.) Moreover, we avoid contamination through any effects of expectations on prime processing (cf. Kunde et al., 2003) by using only primes that were also presented as clearly visible targets.

Finally, due to the correlational design of our study, the results have to be interpreted very cautiously. For example, it is conceivable that existing differences in cognitive abilities are responsible that people play action video games (cf. Boot et al., 2011; Kristjánsson, 2013). We thus take this study as a first step to demonstrate differences in stimulus-response translation processes for hardly visible stimuli. Of course, to establish unequivocal evidence for causal relation and to elucidate the exact kind of training required to faster process shortly presented stimuli, training studies are necessary.

To conclude, the results of our study are well in line with recent studies that demonstrated that action video game expertise is related to more efficient visual and cognitive processing. This expertise related processing advantage is especially interesting because the effects of expertise, i.e., improvement of executive functions as well as perceptual learning, generalize to new tasks and are not restricted the domain of the original expertise.

In addition, our results are interesting for research on masked priming because our results are well in line with other studies that observed an impact of expertise on prime processing. However, in all other studies expertise-related stimuli such as the own face (Pannese and Hirsch, 2010), the own name (Pfister et al., 2012), pictures of athletic jumps (Güldenpenning et al., 2011), chess configurations (Kiesel et al., 2009), and words in the mother tongue (Schoonbaert et al., 2009) were used to demonstrate expertise-related lager congruence effects. In the present study we used drawn pictures of animals as stimuli that can be assumed to be of equal familiarity for VGPs and NVGPs. Nonetheless VGPs produced larger congruence effects than NVGPs for primes with a very short duration (20 ms), whereas this group difference was eradicated when the prime duration was prolonged (to 60 ms). Thus, expertise related advantages seem restricted to shortly presented primes and they do not need to be restricted to expertise-related stimulus material.

To our knowledge, this is the first study to demonstrate a relation of video gaming and masked prime processing at a conceptual level based on a more efficient stimulus-response translation, extending findings that action video game training increased prime detection in a backward masking setting (Li et al., 2010). Bearing in mind all the connected caveats, it seems nevertheless appropriate to recommend that action video game experience should be considered in masked priming studies. Especially when between-group comparisons of priming effects are reported, action video game experience is an important factor to control for that might account for group differences particularly when investigating small sample sizes.

#### **ACKNOWLEDGMENTS**

This publication was funded by the German Research Foundation (DFG) and the University of Wuerzburg in the funding programme Open Access Publishing, as well as through DFG Grant Ku 1964/7-1.

#### **REFERENCES**

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

*Received: 06 September 2013; accepted: 18 January 2014; published online: 05 February 2014.*

*Citation: Pohl C, Kunde W, Ganz T, Conzelmann A, Pauli P and Kiesel A (2014) Gaming to see: action video gaming is associated with enhanced processing of masked stimuli. Front. Psychol. 5:70. doi: 10.3389/fpsyg.2014.00070*

*This article was submitted to Cognition, a section of the journal Frontiers in Psychology.*

*Copyright © 2014 Pohl, Kunde, Ganz, Conzelmann, Pauli and Kiesel. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.*

# An investigation of the validity of the virtual spatial navigation assessment

# *Matthew Ventura1\*, Valerie Shute1, TimWright 2 and Weinan Zhao1*

*1 College of Education, Florida State University, Tallahassee, FL, USA*

*2 Department of Psychology, Florida State University, Tallahassee, FL, USA*

#### *Edited by:*

*Bernhard Hommel, Leiden University, Netherlands*

#### *Reviewed by:*

*Mark Neider, University of Central Florida, USA Hyunkyu Lee, Brain Plasticity Institute, USA*

#### *\*Correspondence:*

*Matthew Ventura, College of Education, Florida State University, 3205A Stone Building, 1114 West Call Street, Tallahassee, FL 32306-4453, USA*

*e-mail<EMAIL_ADDRESS>
This correlational study investigated a new measure of environmental spatial ability (i.e., large scale spatial ability) called the virtual spatial navigation assessment (VSNA). In the VSNA, participants must find a set of gems in a virtual 3D environment using a first person avatar on a computer. The VSNA runs in a web browser and automatically collects the time taken to find each gem. The time taken to collect gems in the VSNA was significantly correlated to three other spatial ability measures, math standardized test scores, and choice to be in a STEM (science, technology, engineering, or math) career. These findings support the validity of the VSNA as a measure of environmental spatial ability. Finally, self-report video game experience was also significantly correlated to the VSNA suggesting that video game may improve environmental spatial ability. Recommendations are made for how the VSNA can be used to help guide individuals toward STEM career paths and identify weaknesses that might be addressed with large scale spatial navigation training.

**Keywords: environmental spatial ability, vista spatial ability, figural spatial ability**

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# **INTRODUCTION**

Spatial ability has been shown to play a significant role in achievement in science, technology, engineering, and mathematics (STEM) disciplines. For instance, Wai et al. (2009) showed that spatial ability was a significant predictor of STEM degree attainment, even after controlling for mathematical and verbal skills. Thus a thorough understanding of spatial ability and how it can be improved should be considered paramount in understanding how to engage students in STEM related fields.

One way spatial ability can be improved is through playing action video games (e.g., Dorval and Pepin, 1986; Subrahmanyam and Greenfield, 1994; De Lisi and Wolford, 2002; Green and Bavelier, 2006; Feng et al., 2007; Spence et al., 2009; Uttal et al., 2012).  After only 10 h of training with an action video game, subjects showed gains in spatial ability via mental rotation tasks, with females performing equal to males after training. Control subjects who played a non-action game showed no improvement. Recently, Uttal et al. (2012) conducted a meta-analysis of 206 studies investigating the effect of training on spatial ability. Of these 206 studies, 24 used video games to improve spatial ability. The effect size for video game training was 54 (SE = 0.12). Findings like these have been explained due to the visual-spatial requirements of 3D action games which may enhance spatial abilities (e.g., Feng et al., 2007). However, others have found a lack of transfer effects between action video game playing and basic cognitive functions and skills (e.g., Boot et al., 2008) and have raised questions regarding the methodology of studies that observe transfer (Boot et al., 2013; Kristjánsson, 2013).

Of particular importance in understanding the malleability of spatial ability is the distinction between figural, vista, and environmental related spatial abilities (Montello, 1993; Montello and Golledge, 1999). Figural spatial ability is small in scale relative to the body and external to the individual. It can be apprehended from a single viewpoint in both flat pictorial and 3D space (e.g., small, manipulatable objects). It is most commonly associated with tests such as mental rotation and paper folding tasks. Vista spatial ability is the ability to imagine oneself in different locations within a small space without locomotion. Vista spatial ability is useful when trying to image how the arrangement of objects will look from various perspectives (Hegarty and Waller, 2004). Environmental spatial ability is large in scale relative to the body and is useful in navigating around large spaces such as buildings, neighborhoods, and cities, and typically requires locomotion (see Montello, 1993; for a discussion of other scales of space). Environmental spatial ability may require a person to mentally construct a cognitive map, or internal representation of the environment (Montello and Golledge, 1999).

Specific processes in environmental spatial ability may result from the accumulation of three main types of knowledge of the environment: landmark, route, and configurational knowledge (Tolman, 1948; Siegel and White, 1975). First, landmark knowledge is acquired of perceptual objects through visual encoding. These perceived landmarks are then assimilated and are connected sequentially along a traversed path into route knowledge. Configurational knowledge is formed through the amassing of route knowledge, as a map-like representation of the environment is formed that allows for navigational inferences (Siegel and White, 1975). For example, new routes and distance and direction judgments can be formed as a result of a navigator's configurational knowledge. The details of these environmental representations depend on a number of factors including the perception of environmental information, the speed in which the information is encoded, and how the information is maintained (Ittelson, 1973).

Existing measures of environmental spatial ability include map retracing, distance estimation, direction estimation (Hegarty et al., 2006), and self-report measures (Hegarty et al., 2002). Map retracing and distance and direction estimation (Hegarty et al., 2006) require a participant first to navigate through an environment (real world, 3D virtual environment, or first-person video). Afterwards, a person can be asked to (a) judge the distance among various features in the environment, (b) provide direction estimates among features in the environment, or (c) draw a 2D map of the environment. While these measures may seem distinct, factor analysis has revealed that these three measures were highly correlated and loaded on one factor, suggesting they measure a common ability (Hegarty et al., 2006). Additionally, factor analysis has shown measures based on virtual and video environments load on one factor (video factor) while measures based on real environments load on a second factor (real environment factor). The correlation between the two factors was high (*r* = 0.61) suggesting that the cognitive processes being used in virtual simulations are similar to the ones being used in real environments (Hegarty et al., 2006).

#### **THE PRESENT STUDY**

Hegarty et al. (2006) proposed three main sources of variance in environmental spatial ability: (1) ability to encode spatial information from sensory experience, (2) ability to maintain a high quality internal representation of that information in memory, and (3) ability to perform spatial transformations in order to make inferences from this spatial information. In line with this theory, we developed the Virtual Spatial Navigation Assessment (VSNA). Advances in game development software now enable researchers with little programing experience to create virtual environments. These virtual environments are increasing being used to assess large scale spatial ability. For example, Herting and Nagel (2012) created a virtual water maze task to assess visuospatial memory. The VSNA requires a participant to explore a virtual 3D environment using a first person avatar on a computer. One significant difference between the VSNA and traditional measures of environmental spatial ability (e.g., map retracing) is that the VSNA collects data while a person is *in* the environment itself as opposed to collection of data *post hoc outside* of the environment. Measures (e.g., direction and distance estimation) based on one's memory of an environment may be a source of construct irrelevant variance in the assessment of environmental spatial ability (Hegarty et al., 2006). Additionally, measurement outside of navigation in the environment requires individuals to make inferences that were not made within the environment (Montello et al., 2004). For example, the ability to point accurately to locations or estimate distances requires one to remember spatial configurations encoded in an environment. Assessing navigational performance in the task itself removes the additional burden of memory requirements that may contaminate the assessment of environmental spatial ability.

In each VSNA environment, a person must collect a set of brightly colored gems which are scattered throughout the environment. Participants need to complete the task twice for each environment. The first collection of gems is the training phase, which is intended to familiarize the person with the environment. The second collection of gems is the testing phase, which requires the person to obtain all the gems again as fast as possible. While no questions are explicitly asked about distance or direction between objects, the time to complete the VSNA require distance and direction estimation.

In this correlational study, we address two research questions centered around the validity of the VSNA as a measure of environmental spatial ability. The first question refers to how the VSNA relates to other measures of spatial ability. We compare the VSNA to a measure of figural spatial ability (mental rotation test, MRT; adapted from Vandenberg and Kuse, 1978), vista spatial ability (spatial orientation test, SOT;Hegarty andWaller, 2004) and a selfreport measure of environmental spatial ability (SBSOD; Hegarty et al., 2002). In the MRT, participants view a 3D target figure and four test figures. The task is to determine which two test figures are correct rotations of the target figure as quickly and accurately as possible. The SOT requires the participant to make direction estimations from different perspectives relative to a 2D picture. For example, the person may be asked to give the direction of a car from the perspective as if the person is standing at a tree facing a traffic light. The degree to which a person can give the correct direction of objects from various perspectives is proposed to assess vista spatial ability. The SBSOD scale measures a person's selfreport belief about various navigation abilities in the real world (e.g., I don't have a very good "mental map" of my environment, I enjoy reading maps). The SBSOD has been found to correlate (e.g., *r* = 0.44) with tests of spatial knowledge that involve orienting oneself within real-life environments (Hegarty et al., 2002). We also compare the VSNA to verbal and math scholastic aptitude test (SAT) scores since spatial ability has been shown to correlate to math achievement but not verbal achievement (e.g., Hegarty et al., 2006). Thus we expect to show divergent validity of the VSNA by showing it does not relate to verbal SAT scores.

Finally, regarding criterion related validity, we will investigate the relationship between the VSNA scores and choosing a STEM career path. Addressing this question expands on the work by Wai et al. (2009) showing that spatial ability predicts STEM degree attainment.

We make the following hypotheses regarding question one:

(1) *The VSNA should relate more to the SBSOD scale than the SOT and the MRT.*While the SOT and the MRT have been shown to relate to the SBSOD scale (e.g., Kozhevnikov and Hegarty, 2001), the VSNA should more accurately assess environmental spatial ability than the MRT or the SOT.

(2) *The VSNA will relate higher to math SAT scores than verbal SAT scores.* Spatial skills correlate to math achievement (e.g., Hegarty et al., 2006). Therefore the VSNA should relate more to math SAT scores than to verbal SAT scores.

(3) *The VSNA, SOT, and MRT will relate to STEM career path and achievement after controlling for gender, verbal and math ability (via SAT scores).* Spatial ability has been found to predict STEM degree attainment (Wai et al.,2009). Thus we expect to see a similar result for the VSNA as well as for the MRT and SOT.

The second question refers to the extent to which video game use influences environmental spatial ability (as measured by the VSNA). The question further addresses the malleability argument that video game use can impact spatial ability and specifically, environmental spatial ability. While this study focuses on correlational relationships, it is informative since it may show that even casual

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video game use can have a potential effect on environmental as well as vista and figural spatial ability.

Despite the large body of work investigating the role of video games on spatial ability, we are aware of only three studies that have specifically investigated the relationship between video game use and environmental spatial ability (Rehfeld et al., 2005; Schuster et al., 2008; Richardson et al., 2012). Schuster et al. (2008) found that video game experience correlated with college students' ability to plan routes for unmanned vehicles in a 3D virtual simulation.

We make the following hypothesis regarding question two:

(4) *Video game use will relate to performance on all measures of spatial ability (figural, vista, environmental).* Higher video game use will be associated with in better spatial abilities compared to less video game use.

# **MATERIALS AND METHODS**

### **PARTICIPANTS**

323 undergraduate students (129 males, 194 females) enrolled in introductory psychology and education courses at a large southeastern state university volunteered to participate in the study for course credit.

# **MEASURES**

# *Virtual spatial navigation assessment*

The VSNA was created in Unity, a free video game development software tool. In the VSNA, a participant explores a virtual 3D environment using a first person avatar on a computer. The avatar is controlled by a single key on the keyboard and the mouse. Pressing the key moves the avatar forward and the mouse controls the direction of the avatar. Participants are instructed that the goal is to collect three gems in an environment and return to the starting position. Participants first complete a short familiarization task that requires them to collect three gems in a small room.  In each environment three gems are strategically located in the four environments so that an optimal path can be used to collect all the gems. In each environment the participant must collect the gems twice. The first collection is the training phase and the second collection is the testing phase. **Figure 1** displays a screenshot of the easy indoor environments.

The VSNA records the time taken to complete the training and testing phases per environment (i.e., time taken to collect the gems). The training phase is intended to measure one's ability to *search* and *encode* information in the environment, while the testing phase is intended to measure one's ability to *retrieve* and *apply* the encoded information. There is a 5 min time limit (per phase) in the easy indoor environment. The hard indoor and both outdoor environments each have a 10 min time limit per phase. If a person times out in a training phase, the participant skips the testing phase and goes to the next environment. The automated skip was done to keep the testing phase a recall task not a searching task. Lower score indicate higher environmental spatial ability. For ease of reading we reverse coded the VSNA scores so higher scores mean better performance.

# *The Santa Barbara sense of direction scale (Hegarty et al., 2002)*

This test consists of 15 self-report items pertaining to environmental spatial ability (e.g., I am good at reading maps) that are rated on a five point likert scale. Higher score indicate higher environmental spatial ability.

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**FIGURE 1 | Indoor environment in the VSNA.**

#### *Spatial orientation test (Hegarty and Waller, 2004)*

This test consists of 12 questions requiring the participant to estimate locations of objects from different perspectives in one picture. In each item the participant is told to imagine looking at one object from a particular location in the picture and then point to a second location. An example item is as follows: *Imagine you are looking at the tree from the position of the cat, now point to the car*. The participant must draw the direction in a circle relative to an arrow in the circle that is always pointing to the 12 o'clock position. Each response is scored as a difference between the participant's angle and the correct angle (ranges from 0◦ to 180◦). Larger differences between a participant's drawn angle and the correct angle indicate lower vista spatial ability. For ease of reading we reverse coded the SOT scores so higher difference scores mean greater vista spatial ability.

#### *Mental rotation test (adapted from Vandenberg and Kuse, 1978)*

In this test, participants view a three-dimensional target figure and four test figures. Their task is to determine which of the test figures are rotations of the target figure. The MRT has two correct answers for each of the 10 items. The total score is based on the total number of items where both correct objects arefound. Higher score indicate higher figural spatial ability.

#### *Video game use and VSNA-video game similarity*

Participants answered one question about general video game use: How often do you play video games? 1 = not at all, 2 = about once a month, 3 = a few times a month, 4 = a few times a week, 5 = everyday, but for less than 1 h, 6 = every day for 1–3 h, 7 = every day for more than 3 h (Jackson et al., 2012). Additionally, participants were asked a question about the similarity between the VSNA and the video games they play: How similar was the navigation task to a video game you play (not at all, somewhat similar, similar, very similar, completely identical)?

#### **PROCEDURE**

The study was conducted online in a web browser without supervision. Participants first reported their GPA, SAT scores, academic major, and completed the SBSOD scale. Then they completed the VSNA, the SOT, and the MRT. Finally, they completed some questions about video game use and usability of the VSNA. No tests were counterbalanced since we wanted to see how participants performed on the VSNA without the influence of fatigue from other spatial ability tests.

#### **RESULTS**

**Table 1** displays the means and standard deviations of the SBSOD, times across the eight phases of the VSNA, the SOT, and MRT (listed in the order they were presented). Due to the difficult nature of theVSNA hard environments, and the study being unproctored, not all participants completed all tests. In some cases a participant timed-out of a training environment which results in the participant skipping its corresponding testing phase (as described in the VSNA measures section). In order to maximize power we still included participants in analysis who completed the training phase for each environment.

Reliability was good for the SBSOD (α=0.89), MRT (α=0.76), and SOT (α = 0.87). Based on the high correlation between VSNA testing and training times (*r* = 0.61), we took the average score across training and testing. Easy and hard times were also highly related (*r* = 0.56) so we took the average score across easy and hard times to yield an indoor and outdoor VSNA score. While the correlation between indoor and outdoor environments was also high (*r* = 0.53), we report results for them separately since the sample size differs between the indoor and outdoor environments. Additionally, combining the time data across the indoor and outdoor environments could give an added advantage to participants who did not complete the outdoor task (i.e., give lower means to a person who did not complete the outdoor versus a person who did complete the outdoor).

We recoded students' self-reported major into two categories: STEM related and non-STEM related. Examples of STEM related majors include: biology, engineering, computer science, and chemistry. Examples of non-STEM related majors include: English, education, business, communication, and history. Nonmajors (*n* = 36) were excluded from the STEM major variable. **Table 2** displays the correlations between STEM career path (0 = non-STEM, 1 = STEM), gender (males = 0, females = 1), SAT math scores, MRT, SOT, and the indoor and outdoor VSNA scores (time data, where less time is better). GPA was omitted from **Table 2** since it did not relate to any spatial ability measures.

Regarding hypothesis one (i.e., VSNA should relate more to the SBSOD scale than the SOT and the MRT) both the indoor and outdoor VSNA scores significantly relate to the SBSOD, MRT, and the SOT. However, only the indoor VSNA scores appear to support hypothesis one: indoor VSNA scores are more highly correlated to the SBSOD (*r* = 0.37) relative to the MRT (*r* = 0.24) and the SOT (*r* = 0.18). The Steiger test (1980) was conducted to test if the VSNA indoor scores are significantly higher to the SBSOD versus the MRT and SOT (using a one-tailed test). The difference between the SBSOD (*r* = 0.37) and SOT (*r* = 0.18) is significant (*z* = 2.51, *p* < 0.05). The difference between SBSOD (*r* = 0.37)

#### **Table 1 | Means and SDs of the SBSOD, VSNA phases, SOT, and MRT.**

*\*Measured in seconds*

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**Table 2 | Correlations (***r***) among gender, STEM major, SAT, spatial measures, and video game experience.**

*\*p* < *0.05; \*\*p* < *0.01; SATm, SAT math; VG use, video game experience*

and MRT (*r* = 0.24) is significant (*z* = 1.74, *p* < 0.05). The VSNA indoor and outdoor times both account for unique variance in the SBSOD after controlling for MRT and SOT scores (*pr* = 0.36, *p* < 0.001; *pr* = 0.18, *p* < 0.001).

Regarding hypothesis two (i.e.,VSNA will relate higher to math SAT scores than verbal SAT scores), all spatial ability measures related to SAT math scores. No spatial ability measures related to GPA or verbal SAT.

Regarding hypothesis three (i.e., VSNA, SOT, and MRT will relate to STEM major and achievement after controlling for gender, verbal and math ability), gender, SAT math scores, SBSOD, and both indoor and outdoor VSNA scores significantly relate to STEM majors. A hierarchical regression was run to predict STEM major. Predictors were entered in the following order: gender, math SAT scores, SBSOD scores, and finally VSNA indoor scores. Only VSNA indoor was a significant predictor of STEM interest after controlling for all other predictors (std β = 0.24, *p* < 0.01; *R*2 change = 0.04, *F*(1,219) = 10.13, *p* < 0.05). The same analysis was conducted entering VSNA outdoor scores last (gender, math SAT scores, SBSOD scores, VSNA outdoor scores) but the *R*2 change was not significant. GPA did not relate to any spatial ability measures for the STEM majors (*n* = 119).

Regarding hypothesis four (i.e., video game use will relate to performance on all measures of spatial ability), video game use significantly relates to the four spatial ability measures. However, after controlling for gender and video game similarity (for VSNA only), video game use only relates to SOT (*pr* = 0.21, *p* < 0.01) and VSNA indoor scores and (*pr* = 0.15, *p* < 0.05).

# **DISCUSSION**

Hypothesis one (i.e., VSNA should relate more to the SBSOD scale than the SOT and the MRT) was partially confirmed. We found that indoor VSNA scores had moderately highly correlations to SBSOD scores than to MRT and SOT scores. Both the VSNA indoor and outdoor scores accounted for unique variance in the SBSOD after controlling for MRT and SOT scores. These findings partially supports the construct validity of the VSNA as a measure of environmental spatial ability. We did not find evidence of construct validity for the outdoor VSNA scores (i.e., outdoor scores were more highly correlated to the MRT than to SBSOD). This finding may be due to the outdoor environments always being after the indoor environments which could cause fatigue effects on the outdoor environments. Finally, method effects (i.e., different task requirements) and well known psychometric issues related to self-report measures (e.g., social desirability) could be a reason why the correlation was not higher between the SBSOD and the VSNA.

Hypothesis two (i.e., VSNA will relate higher to math SAT scores than verbal SAT scores) was confirmed. We found that the VSNA, MRT, and SOT scores were all significantly related to math SAT scores and not verbal SAT scores. This is consistent with other research (e.g., Hegarty et al., 2006) that has shown a relation between mathematical and spatial abilities. This finding further supports the construct validity of the VSNA as a measure of spatial ability.

Hypothesis three (i.e., VSNA, SOT, and MRT will relate to STEM major and achievement after controlling for verbal and math ability) was partially supported. The VSNA indoor scores significantly correlated to being a STEM career path after controlling for gender, math SAT scores, and SBSOD scores (verbal SAT scores were not related to STEM career path). Thus we established criterion related validity of the VSNA. This finding extends the work by Wai et al. (2009) who showed that spatial ability was a significant predictor of STEM career path, even after controlling for math and verbal skills. However, we did not find the VSNA outdoor scores predicted STEM career path. This may be due to the lower number of participants who completed the outdoor VSNA. We also did not find that figural or vista spatial ability related to STEM career path. Thus environmental spatial ability may be a unique spatial ability separate from figural and vista ability that affects STEM career path. Additionally, no spatial ability measures related to GPA. Spatial ability may not give students an added academic advantage in STEM courses. However, the GPA variable was based on a variety of courses outside of STEM subjects. Future work research should investigate how environmental spatial ability relates to grades and performance in specific STEM courses.

Hypothesis four (i.e., video game use will relate to performance on all measures of spatial ability) was partially supported. Video game use was significantly correlated with the SOT and the indoor VSNA after controllingfor gender. Importantly, theVSNA does not just assess one's ability to play video games–video game use significantly relates to the VSNA after controlling for VSNA-video game similarity. The relation between video game use and the VSNA might be underestimated considering we only asked a broad question about video game use. Future work should consider using more detailed questions regarding video game use to further identify if specific video game use (e.g., 3D video games) relates more strongly to the VSNA.

A case can also be made that the VSNA-video game similarity question might not be sufficient to measure how similar the VSNA is to video games. For example, a particular video game player might see lots of differences between the VSNA and video games in general (e.g., lack of controls, gameplay options), while another video game player might see lots of similarities (e.g., first-person exploration in a 3D world). Future work should consider more detailed questions regarding the similarity between the VSNA and video games. However, the VSNA requires little motor control beyond skills learned by normal computer use (single button press with one hand and mouse control with the other hand). In this regard, the VSNA can be seen as a transfer task of environmental spatial ability independent from other video game play heuristics (e.g., effective use of controllers). These results are consistent with experimental evidence that video game use can improve spatial ability (e.g., Uttal et al., 2012). Thus exposure to video games may affect one's ability to encode, store, retrieve, and apply environmental spatial information. Contrary to this theory, Richardson et al. (2012) found video game use was related to a pointing task after navigating through a virtual environment but not a pointing task after navigating through a real environment. However, Richardson et al. (2012) states the limitation of using pointing tasks to assess environmental spatial ability in that pointing tasks do not require actual navigation to targets. Thus it is possible that video game use does improve actual navigation performance *in* real environments (i.e., environmental spatial ability) but not to pointing performance *after* navigating through real environments.

Finally, the positive relation between video game use and environmental spatial ability also shows what lifestyle factors might indirectly affect interest in STEM (i.e., both the VSNA and SAT math scores relate to STEM major). While we did not find that video game use directly relates to STEM interest, video game use may indirectly affect interest in STEM by positively affecting environmental spatial ability and math ability.

Consistent with other work on spatial abilities (e.g., Spence et al., 2009), we found robust gender differences among the spatial ability measures. Females scored significantly worse on the SBSOD, SOT, MRT, and the VSNA (indoor and outdoor) compared to males. Follow up analysis revealed that after controlling for video game experience this gender effect was only eliminated for performance on the SOT. Future research should investigate how training can eliminate the gender gap in environmental spatial ability.

Looking forward, the VSNA could potentially be used for large scale assessment since it is scalable (i.e., run in a web browser) and quick to administer (as short as 10 min). This is important due to the growing number of studies suggesting the need to assess spatial ability in our education system (e.g., Wai et al., 2009; Uttal et al., 2012). There are many STEM related careers (e.g., engineering, medicine) and non-STEM careers (e.g., transportation, military, tourism) that require high levels of environmental spatial ability. These fields could benefit from having an assessment to be used for selection as well as intervention work. Additionally, the VSNA is a performance-based assessment not subject to social desirability effects. This gives it an advantage over traditional environmental spatial ability measures (e.g., SBSOD). Finally, assessment studies of environmental spatial ability using the VSNA can be covert since the gem finding activity does not explicitly cue participants about the purpose of the VSNA. This can be useful in situations where test anxiety could potentially affect the validity of the test.

This study cannot rule out the selection hypothesis that people with high environmental spatial ability may enjoy playing video games more than people with low environmental spatial ability. Future work should focus on experimental research investigating how using 3D simulations or video games can improve performance in the environmental spatial ability. Another limitation in this study was students completed all tests online without proctor supervisions. Results might have been more robust if participants were directed to stay on task throughout the session.

Another limitation of this study was we were not able to investigate the latent factorial structure of the VSNA. Given the limited time we had to run reach participant we could only investigate two levels of difficulty (easy vs. hard) in two distinct environments (indoor vs. outdoor). Future work should investigate creating "forms" of the VSNA that contain multiple isomorphic environments of similar difficulty (e.g., five outdoor nature environments). These forms can be compared to other forms that contain other features of the VSNA (e.g., five outdoor nature environments, five indoor environments, five outdoor urban environments). This design allows for confirmatory factor analysis and structural equation modeling. Additionally, counterbalancing and time spacing between forms should be implemented to control for any fatigue effects that may be occurring as a function of extended VSNA testing.

Finally, virtual environments do not provide any information to body-based senses (i.e., vestibular, proprioceptive) and thus may afford less detailed representations than real world environments (Waller et al., 2004; Richardson et al., 2012). However, Wan et al. (2009) provide evidence that participants still spatially update (e.g., remember locations of objects and landmarks) information in virtual environments much like in real environments. Future work should investigate how performance in the VSNA relates to real world navigation tasks.

# **ACKNOWLEDGMENTS**

We would like to gratefully acknowledge support for this research provided by the D. John and T. Catherine MacArthur Foundation. The views expressed herein are those of the authors and do not reflect the views of the funding foundation.

# **REFERENCES**

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Boot, W. R., Kramer, A. F., Simons, D. J., Fabiani, M., and Gratton, G. (2008). The effects of video game playing on attention, memory, and executive control. *Acta Psychol.* 129, 387–398. doi: 10.1016/j.actpsy.2008. 09.005

*11th Annual Human-Computer Interaction International Conference*, (Las Vegas: Human Factors and Ergonomics Society, CD-ROM).

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

*Received: 26 September 2013; accepted: 27 October 2013; published online: 13 December 2013.*

*Citation: Ventura M, Shute V, Wright T and Zhao W (2013) An investigation of the validity of the virtual spatial navigation assessment. Front. Psychol. 4:852. doi: 10.3389/fpsyg.2013.00852*

*This article was submitted to Cognition, a section of the journal Frontiers in Psychology. Copyright © 2013 Ventura, Shute, Wright and Zhao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.*

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# A new adaptive videogame for training attention and executive functions: design principles and initial validation

# *Veronica Montani 1, Michele De Filippo De Grazia1 and Marco Zorzi 1,2,3 \**

*1 Department of General Psychology, University of Padova, Padova, Italy*

*2 Center for Cognitive Neuroscience, University of Padova, Padova, Italy*

*3 IRCCS San Camillo Neurorehabilitation Hospital, Venice Lido, Italy*

#### *Edited by:*

*Walter R. Boot, Florida State University, USA*

#### *Reviewed by:*

*Evan Palmer, Wichita State University, USA Joseph Chisholm, University of British Columbia, Canada*

#### *\*Correspondence:*

*Marco Zorzi, Department of General Psychology, University of Padova, Via Venezia 8, 35131 Padova, Italy e-mail<EMAIL_ADDRESS>
A growing body of evidence suggests that action videogames could enhance a variety of cognitive skills and more specifically attention skills. The aim of this study was to develop a novel adaptive videogame to support the rehabilitation of the most common consequences of traumatic brain injury (TBI), that is the impairment of attention and executive functions. TBI patients can be affected by psychomotor slowness and by difficulties in dealing with distraction, maintain a cognitive set for a long time, processing different simultaneously presented stimuli, and planning purposeful behavior. Accordingly, we designed a videogame that was specifically conceived to activate those functions. Playing involves visuospatial planning and selective attention, active maintenance of the cognitive set representing the goal, and error monitoring. Moreover, different game trials require to alternate between two tasks (i.e., task switching) or to perform the two tasks simultaneously (i.e., divided attention/dual-tasking). The videogame is controlled by a multidimensional adaptive algorithm that calibrates task difficulty on-line based on a model of user performance that is updated on a trial-by-trial basis. We report simulations of user performance designed to test the adaptive game as well as a validation study with healthy participants engaged in a training protocol. The results confirmed the involvement of the cognitive abilities that the game is supposed to enhance and suggested that training improved attentional control during play.

**Keywords: videogames, attention, attention deficits, executive functions, cognitive enhancement**

# **INTRODUCTION**

Cognitive enhancement through videogame playing is a hot topic in cognitive science. Most of the literature on the effect of videogame play is centred on "action" videogames, which are remarkably challenging in terms of visual and attention demands. Indeed, many investigations have focused on the modulation of visual skills and have revealed that videogame players (VGPs) outperform non-videogame players (NVGPs) on a variety of visuo-attentional tasks (Green and Bavelier, 2003, 2006a; for reviews see Spence and Feng, 2010; Boot et al., 2011; Hubert-Wallander et al., 2011a; Latham et al., 2013). For example, VGPs showed to be better in localizing the target in many different visual search tasks (e.g., Castel et al., 2005; West et al., 2008; Hubert-Wallander et al., 2011b), they were better in suppressing irrelevant information (e.g., Mishra et al., 2011; Wu et al., 2012) and in general they showed to have more available attentional resources (e.g., Green and Bavelier, 2003, 2006b; Dye et al., 2009a).

Nevertheless, there is also evidence that videogame playing enhances a variety of other cognitive skills (Green and Bavelier, 2003; Dye et al., 2009a; Anguera et al., 2013) and that cognitive processes different from visuo-spatial ability might benefit from playing more strategic games (e.g., Basak et al., 2008). For example, Colzato et al. (2010)reported that VGPs suffer smaller task switching cost than NVGPs, suggesting that they have better cognitive

control (see also Cain et al., 2012; Strobach et al., 2012). Karle et al. (2010) suggested that the smaller switch cost is the consequence of more efficient task reconfiguration due to a superior ability to control attentional resources (also see Meiran et al., 2000).

Action videogame playing also seems adequate for training executive control skills that are crucial for the coordination of different tasks in complex situations. For example, Strobach et al. (2012) showed that VGPs outperformed NVGPs in a dual task condition (but see Donohue et al., 2012, for contrasting results) and, even more convincingly, that non-gamers trained with an action videogame suffered less dual-task cost after training in comparison to non-gamers trained with a puzzle game. It is worth nothing that the latter result was confirmed in the study of Chiappe et al. (2013) using a more complex task that was shown to predict performance in real-life settings.

Selective and controlled aspects of attention appear to benefit more of videogame playing relative to transient, automatic aspects (Chisholm et al., 2010). Clark et al. (2011) suggested that better performance of VGPs is explained by an improvement in higher-level abilities such as attentional control, in addition to better bottom-up visual processing. Accordingly, a neuroimaging study confirmed lesser recruitment of the network associated with the control of top-down attention in VGPs, despite their superior performance in a visual search task relative to NVGPs (Bavelier et al., 2011). This result was interpreted as evidence that VGPs are more efficient in the allocation of attention.

Studies comparing VGPs and NVGPs on many different tasks invariably show that VGPs are faster across a wide range of tasks and they do not show speed-accuracy trade-offs (Dye et al., 2009b; but see Nelson and Strachan, 2009). Moreover, videogame training was shown to be a helpful training regimen for providing a marked increase in speed of information processing in elderly (Drew and Waters, 1986; Clark et al., 1987; Anguera et al., 2013).

It is worth noting that most of these studies do not establish a causal link between videogame play and cognitive enhancement because they do not control for pre-existing differences between VGPs and NVGPs (Kristjánsson, 2013). However, some studies have compared the performance of two groups of non-players before and after a different type of training. For example, an action videogame was compared to a game that made heavy demands on visuomotor coordination but, unlike action video games, did not require the participant to process multiple objects at once at a fast pace. Action-trained participants showed greater traininginduced improvements than participants trained on a control game, thereby showing that the benefits of play are trainable to a non-game player population (Green and Bavelier, 2003, 2006a,b; Feng et al., 2007; Strobach et al., 2012). There is also some evidence that learning/enhancement is not specific to the trained task but there is some degree of generalization to untrained aspects (Green and Bavelier, 2006b; Mathewson et al., 2012) and some transfer to a completely different and more "ecological" domain (Gopher et al., 1994; Rosenberg et al., 2005; see Boot et al., 2011, for a critical discussion).

The aim of the present study was to develop a novel adaptive videogame for training attention and executive functions, with particular emphasis on design features that make the game suitable for brain-damaged patients as a tool to support cognitive rehabilitation. Despite some contrasting findings (Boot et al., 2008; Murphy and Spencer, 2009; Irons et al., 2011), videogames seem to enhance a variety of cognitive skills and they appear to be a promising tool to train cognitive abilities (e.g., Achtman et al., 2008; Basak et al., 2008; Anguera et al., 2013; Franceschini et al., 2013). Moreover, neuroplasticity in the adult brain could be guided with specific training to yield better recovery (e.g., Krainik et al., 2004; Gehring et al., 2008). The rationale for designing a new videogame, despite the great variety of commercial videogames that are currently available, was twofold. First, designing a novel videogame allows the inclusion of specific features in a theory-driven manner as well as to implement a fine control of the difficulty dimensions, including trial-by-trial adaptation to user performance. Second, the graphical user interface of commercial videogames might be too demanding for patients with cognitive deficits in terms of speed, visual complexity, or motor requirements.

Before presenting the videogame, we start with a discussion of the theoretical principles that guided our design choices in terms of structure and features of the game. We then report a modeling study in which we simulated users with different abilities to assess the efficiency of the adaptive algorithm in estimating the "performance space" of the user, which is crucial for the online adjustment of game difficulty. Finally, we validated the game with

unimpaired participants (healthy young adults) to ensure that the game involves the activation of the desired cognitive functions as well as to assess the effect of a short training period (<10 h over 2 weeks). Note that the evaluation of videogame training for the rehabilitation of brain damaged patients is left to a future clinical trial.

# **GAME DESIGN PRINCIPLES**