Integrating memories to guide decisions

- Flexible decisions require the integration of memories for past experiences.
- We review evidence for two separate mechanisms by which memories can be integrated.
- Prospective integration evaluates future outcomes at the time a decision is made.
- Retrospective integration integrates memories before a decision is ever faced.
- These mechanisms relate to neural processes in the hippocampus and PFC.

Adaptive decisions are guided by past experience. Yet, decisions are often made between alternatives that have not been directly experienced before, requiring the integration of memories across multiple past events. We review emerging findings supporting at least two seemingly distinct mechanisms for how the brain draws on memories in the service of choice. Prospective integration is triggered when a new decision is faced, allowing inferences to be drawn on the spot. A complementary retrospective mechanism integrates existing memories into a network of related experiences before a decision is actually faced. We discuss evidence supporting each of these mechanisms and the implications for understanding the role of memory in decision-making.