Salient experiences enhance mundane memories through graded prioritization.

Abstract

Salient experiences open temporal windows that boost otherwise mundane memories encoded before and after pivotal events. A proposed feature of this phenomenon is its selectivity: Salient stimuli preferentially strengthen weak memories that share semantic connections. However, evidence in humans remains inconclusive, and a key question persists: Which factors determine the presence and magnitude of memory enhancement within current neurobiological and behavioral frameworks? We present results from 10 independent studies with a total of 648 participants and provide clear evidence of both retroactive and proactive enhancements in weak memories, directly addressing ongoing debates about the existence of these effects. Notably, stronger salience learning facilitates proactive, but not retroactive, memory enhancement, challenging prevailing theories about salience's role in these processes. Instead, retroactive enhancement depends on the proximity between incidentally encoded and conditioned stimuli in a high-level feature embedding extracted from a convolutional neural network, revealing a graded prioritization mechanism. These findings offer insights into the mechanisms driving the consolidation of everyday experiences.