Stress enhances memory for previously encoded events depending on stressor recall.

Abstract

Stressful events are typically well remembered, but their effects on memory for surrounding neutral events and the underlying mechanisms remain less clear. We hypothesized that stress would enhance memory for events surrounding the stressor, contingent on the memory of the stressor itself. Additionally, we predicted that memory for neutral events would be modulated by pairing them with stressor-related cues. To test these hypotheses, 122 healthy participants encoded a series of images before and after experiencing a stressful or control episode. During encoding, images were preceded by cues from stressor or control contexts. Memory for the stress or control episode and the encoded images was tested 24 h later. Our results showed enhanced memory prioritization, reflected in better memory for central versus peripheral features, for the stressful compared to the control episode. Exposure to the stressful episode further enhanced memory for neutral images preceding the stressor. However, this memory boost occurred only in participants with enhanced memory prioritization for the stressor. Memory for stimuli encoded after the stressor remained unaffected, and there was no evidence for the proposed cueing mechanism. These findings indicate that stressful events enhance memory consolidation only when these events themselves are distinctly represented in memory.