204 II. BIOLOGICAL  FOuNDATIONS
failure to control for IQ may produce mis -
leading results. Further, studies of schizo -
phrenia spectrum disorders indicate that 
psychosis risk is negatively associated with 
frontal WM coherence (Canu, Agosta, & 
Filippi, 2015). Taken together, these find -
ings suggest that intellect (which is linked to 
intelligence) and openness (which is linked 
to psychosis risk) are likely to show differ -
ential associations with WM coherence. A 
study examining intellect and openness sep -
arately (and controlling for IQ) found that 
only openness was associated with reduced 
frontal WM coherence (Grazioplene et al., 
2016). The functional consequences of WM 
coherence is not well understood. Tests of 
creativity have also been linked to reduced 
frontal WM coherence (Jung et al., 2010), 
suggesting that lower WM coherence, like 
openness itself, might be associated with 
benefits as well as risks. The human capacity 
for cognitive exploration is extremely com -
plex and sophisticated, rendering it unsur -
prising that O/I would have a complex and 
extensive set of neural correlates.
Conscientiousness
Conscientiousness  reflects the tendency to 
be hardworking, organized, self-  disciplined, 
and orderly. These traits require prioritizing 
nonimmediate goals, following rules, avoid -
ing distractions, and suppressing disruptive 
impulses. Impulsivity is sometimes consid -
ered the opposite of conscientiousness, but 
there are several kinds of impulsivity, and 
some are more closely related to conscien -
tiousness than others (De  Young & Rueter, 
2016; Whiteside & Lynam, 2001). None -
theless, for our purposes in this chapter, we 
consider research on impulsivity together 
with conscientiousness.
Conscientiousness is phylogenetically 
recent. Of numerous species studied, only 
our nearest evolutionary neighbors, bono -
bos and chimpanzees, display a major trait 
dimension analogous to conscientiousness 
(Gosling & John, 1999; Weiss et al., 2015), 
and human beings greatly outstrip even these 
two species in the ability to guide behavior 
toward complex future goals. This ability is 
thought to have arisen primarily through the 
hominid evolutionary expansion of the pre -frontal cortex, which enables complex plan -
ning and problem solving (Bunge & Zelazo, 
2006; E. Miller & Cohen, 2001). A number 
of structural MRI studies have found posi -
tive associations of conscientiousness with 
the volume of regions in dlPFC (Bjørnebekk 
et al., 2013; De  Young et al., 2010; Kapogi -
annis, Sutin, Davatzikos, Costa, & Resnick, 
2013; Riccelli et al., 2017; but see Liu et al., 
2013, for a failure to replicate). Similarly, 
a large study of brain-  damaged patients 
showed that focal lesions of the dlPFC were 
associated with lower conscientiousness 
(Forbes et al., 2014).
The association of conscientiousness 
with dlPFC creates a puzzle, because con -
scientiousness is unrelated, or even slightly 
negatively related, to working memory and 
intelligence, which are commonly linked 
to dlPFC (De  Young et al., 2009, 2014; De -
Young, 2011). However, another major 
functional network, in addition to the fron -
toparietal network, has a node in dlPFC 
(Yeo et al., 2011), and one study ( N = 218) 
indicated that functional connectivity in this 
network is positively associated with consci -
entiousness (Rueter, Abram, MacDonald, 
Rustichini, & De  Young, 2018). This net -
work combines two networks previously 
described as ventral attention  or salience,  
and appears crucial for determining the pri -
ority of goals and reorienting attention away 
from distractors and toward goal-  relevant 
stimuli (Fox, Corbetta, Snyder, Vincent, & 
Raichle, 2006; Uddin, 2015). As mapped by 
Yeo et al. (2011), this goal priority network  
(Rueter et al., 2018) includes regions in the 
right inferior frontal gyrus, anterior insula, 
temporoparietal junction, the middle frontal 
gyrus (in dlPFC), and dorsal ACC and adja -
cent medial frontal cortex.
A number of studies have linked consci -
entiousness, or related traits such as effort -
ful control and impulsivity, to the structure 
of the insula, with most reporting that a 
smaller insula (by metrics such as cortical 
thickness or grey matter volume) was associ -
ated with higher levels of conscientiousness 
(Churchwell & Yurgelun-  Todd, 2013; Liu et 
al., 2013; Nouchi et al., 2016; Riccelli et al., 
2017). In an fMRI study of response inhibi -
tion, impulsivity was negatively associated, 
on trials when inhibition was required, with 
neural activity in the anterior insula and lat -