Observational learning strategies impact the neural correlates of declarative memory formation.

Individuals exhibit variability in their propensity to learn from observing others' behaviors. Here we investigated how individual differences in adopting others' decisions influence both their own choices and subsequent memory for contextual information. In an fMRI-based probabilistic reinforcement-learning task, participants were tasked with either making choices or observing decisions between visual cues, leading to either congruent or opposing outcomes. Following each decision, participants viewed a unique picture and received feedback on the outcome. Participants' choices and subsequent modeling revealed a clear distinction between individuals who distinguished their own decisions from those of others ('Social ignoring' group) and those who integrated information from others into their own decision-making process ('Social learning' group). Only in the 'Social ignoring' group, higher trial-by-trial expected values during observation predicted better memory performance for pictures. fMRI results showed that observing the choices of others activated social cognition regions, while active learning engaged the dmPFC and ventral striatum. Successful image encoding was linked to high-level visual regions and vmPFC, with their activity modulated by stimulus value. The findings suggest that interactions between stimulus-value learning and memory formation are particularly evident during observational learning.