Neural Reactivation Links Unconscious Thought to Decision Making Performance.

Brief periods of unconscious thought have been shown to improve decision-making compared to making an immediate decision. We reveal a neural mechanism for unconscious thought in decision making using BOLD contrast fMRI. Participants (N=33) encoded information on a set of consumer products (e.g., 48 attributes describing 4 different cars), and we manipulated whether participants (1) consciously thought about this information (conscious thought), (2) completed a difficult 2-back working memory task (unconscious thought), or (3) made immediate decisions about the consumer products (immediate decision) in a within-subjects blocked design. In order to differentiate unconscious thought neural activity from 2-back working memory neural activity, participants completed an independent 2-back task and this neural activity was subtracted from neural activity occurring during the unconscious thought 2-back task. Consistent with a neural reactivation account, we found that the same regions activated during the encoding of complex decision information (right dorsolateral prefrontal cortex and left intermediate visual cortex) continued to be activated during a subsequent two-minute unconscious thought period. Moreover, neural reactivation in these regions was predictive of subsequent behavioral decision making performance after the unconscious thought period. These results provide initial evidence for post-encoding unconscious neural reactivation in facilitating decision making.