Abstract
Unconscious thought has been linked with a wide range of mechanisms, capacities, and limits. These claims have changed over time and across different domains of thought. The aim of this review is to synthesise the research on unconscious thinking across the domains of reasoning, judgment, decision making, insight problem solving, and creativity and identify the commonalities between them. Three mechanisms underpin unconscious thought in all of these domains: automaticity, reward-based association, and spreading activation. The mechanisms are triggered by cues in the environment or internal states, and the output of the mechanisms are either specific outputs or affective responses. The mechanisms also define the limits of unconscious thought, expressed here as a “principle of integration”: unconscious thought is not sufficient in tasks or problems that require concepts to be integrated in novel or unfamiliar ways. Where theories have made stronger claims for unconscious thought than this, analysis of the evidence supporting those theories proves equivocal. Nonetheless, unconscious thought based on these mechanisms is adaptive in frequently encountered situations and provides the capacity for highly effective thinking across a range of domains.