 22. The Approach System as a Component of Personality 493
pathway, among other effects (Berton et al., 
2006; Guillin et al., 2001). Both COMT  
and BDNF  have been linked to the strength 
of neural response to reward (Dreher et al., 
2009; Marco-  Pallarés et al., 2009).
Additional neuroimaging studies have 
linked reward sensitivity to activity in opioid 
receptors, which appear relevant for want -
ing and liking rewards and have been im -
plicated in drug addiction (Cui et al., 2014; 
Kawahara et al., 2013). The opioid receptor 
mu-1 gene ( OPRM1 ) guides the function 
of mu opioid receptors and has been linked 
to neural responses to reward, including 
greater neural activation and connectivity in 
reward-  related circuitry (Ray et al., 2014).
Research attempting to link self-  report 
BAS scales to genetic polymorphisms in hu -
mans has had mixed results. Consistent with 
the neuroimaging studies just described, 
much of this work has studied genes asso -
ciated with dopaminergic functioning. In -
dividuals who carry at least one A1 allele 
of the ANKK1  have been found to report 
lower BAS Drive (Felsted et al., 2010) and 
higher BAS Reward Responsiveness (Davis 
et., 2008; Lee et al., 2007). The g allele of 
DRD3  was associated with the BAS Drive 
scale in one sample but not in a second sam -
ple (Henderson et al., 2000). Null findings 
have been found for DAT1  (Henderson et 
al., 2000), DRD2  markers of the 141 Ins/
Del gene (Davis et al., 2008), C957T  muta -
tion related to the D2 receptor (Davis et al., 
2008), and COMT  (Henderson et al., 2000). 
In two studies comparing BAS scores with 
a composite of multiple serotonergic poly -
morphisms, one found a significant associa -
tion among persons exposed to early adver -
sity (Pearson, McGeary, & Beevers, 2014), 
whereas the other did not (Johnson, Carver, 
Joormann, & Cuccaro, 2016). On the other 
hand, the latter found that OPRM1  inter -
acted with early adversity to predict BAS 
Reward Responsiveness.
BAS Outcomes
Individual differences in sensitivity of the 
BAS have been linked to a broad range of 
outcome domains, including goal setting 
and appraisal, affective responses to goal 
progress (or the lack thereof), and interper -sonal relationships. In this section, we ex -
amine evidence that individual differences in 
BAS levels contribute to outcomes in each of 
these domains.
Goal Setting and  Appraisal
It has long been suggested that individual 
differences in BAS ought to differentially 
shape goal-  setting tendencies, such that 
people high in BAS sensitivity would tend to 
set relatively more goals to pursue rewards 
than those lower in BAS sensitivity (Elliot & 
Thrash, 2002). Consistent with theory, high 
BAS scores have been found to relate to ten -
dencies to set more approach-  oriented goals 
(i.e., goals involving moving toward some -
thing) as opposed to avoidance-  oriented 
goals (i.e., goals involving moving away from 
something; e.g., Jones, Shams, & Liversidge, 
2007). For example, persons who are high 
in approach sensitivity, as measured by the 
BAS, are more likely to endorse goals that 
focus on the development of competence 
and mastery as opposed to the avoidance 
of incompetence (Elliot & Thrash, 2002). 
One particularly illustrative finding is that 
high BAS scores have been found to relate to 
increased willingness to set and pursue ex -
tremely ambitious life goals, such as earning 
millions of dollars or appearing regularly on 
TV (Alloy et al., 2012; Johnson & Carver, 
2006).
BAS sensitivity has also been linked to in -
dividual differences in goal-  relevant values 
and appraisals. High BAS scores are asso -
ciated with holding more approach-  oriented 
values, such as performance, achievement, 
and perfectionism (Alloy et al., 2009), and 
to tendencies to favor self-  serving apprais -
als of successful task performance that may 
promote confidence in one’s ability to suc -
ceed (e.g., a tendency to attribute success to 
one’s own internal qualities rather than to 
chance; T. Meyer, Barton, Baur, & Jordan, 
2010).
Affective  Responses
Another class of BAS output is affect. In his 
initial theory, Gray (1994) suggested that 
the affective outcomes of activity in the be -
havioral approach and inhibition systems 
were grouped by valence. More specifically, 