Proceedings of the Annual Meeting of the Cognitive Science Society

How do different forms of contextual change segment ongoing experience into discrete events? How do such boundaries influence memory for information encountered around them? While event boundaries are known to affect recognition memory, their impact on fine-grained mnemonic discrimination remains largely unexplored. Prior work (Morse et al., 2023) reported boundary-related memory effects when multiple sources of contextual change co-occurred, leaving open which type of change is critical. Building on this work, we used a design that separates two sources of contextual change that were previously confounded: shifts in stimulus domain and shifts in task context. We contrasted these by introducing stimulus-domain shifts (image category changes; Experiment 1) and task-context shifts (changes in the encoding judgment; Experiment 2). Following encoding, participants completed recognition and lure discrimination tests. Reliable boundary effects emerged only for task-context shifts, which produced a post-boundary decline in recognition accuracy. Stimulus-domain shifts did not yield comparable effects, and neither manipulation influenced lure discrimination. These findings indicate that shifts in task context alone are sufficient to induce boundary-related memory effects, highlighting a central role for changes in goals and attentional set in event segmentation.