Jeremy Gray & Todd Braver have been developing a theoretical framework in which both motivational orientation (which may be either a stable individual difference, or induced through experimental manipulations) and cognitive ability play key roles in the selection of cognitive control strategy (Gray and Braver, 2002). In this framework, reward-focused orientations lead to a bias towards proactive control, whereas punishment-focused orientations may lead to a bias of reactive control. Likewise, individuals with low fluid intelligence or working memory capacity are predicted to also be biased towards reactive control. This framework suggests that activation in DL-PFC and other parts of the cognitive control system (ACC, DA) will be sensitive to affective and individual difference variables during cognitive task performance. Initial studies have strongly supported this prediction. DL-PFC activity was found to be sensitive to the joint combination of affective state and particular cognitive task (verbal vs. nonverbal WM), but not to either variable in isolation (i.e., a cross-over interaction; Gray, Raichle & Braver, 2002). Within the ACC, individual differences in motivational orientation were found to strongly modulate the degree of task-related activity (Gray & Braver, 2002). Moreover, individual variation in fluid intelligence was found to strongly modulate brain activation during WM task performance, but only within select brain regions (DL-PFC, ACC, parietal cortex), and only under specific conditions (i.e., those placing the highest demands on WM or goal representations to override interference; Gray, Chabris & Braver, 2003).
A current research project involves a large-scale neuroimaging study of emotion and individual differences. Data is being collected on over 100 subjects performing multiple WM tasks under different mood manipulations. Brain imaging and behavioral data will be related to a range of both cognitive and motivational/personality individual difference variables. A second project also examines cognitive and affective individual difference factors in terms of their modulation of brain activity during temporally-extended decision-making.