Perceptual boundaries cause mnemonic trade-offs between local boundary processing and across-trial associative binding.

Abstract

Episodic memories are not veridical records of our lives, but rather are better described as organized summaries of experience. Theories and empirical research suggest that shifts in perceptual, temporal and semantic information lead to a chunking of our continuous experiences into segments, or 'events'. However, the consequences of these contextual shifts on memory formation and organization remains unclear. In a series of three behavioral studies, we introduced context shifts (or 'event boundaries') between trains of stimuli and then examined the influence of the boundaries on several measures of associative memory. In Experiment 1, we found that perceptual event boundaries strengthened associative binding of item-context pairings present at event boundaries.In Experiment 2, we observed reduced temporal order memory for items encoded in distinct events relative to items encoded within the same event, and a trade-off between the speed of processing at boundaries, and temporal order memory for items that flanked those boundaries. Finally, in Experiment 3 we found that event organization imprinted structure on the order in which items were freely recalled. These results provide insight into how boundary-and event-related organizational processes during encoding shape subsequent representations of events in episodic memory.

Transcending time in the brain: How event memories are constructed from experience

“…One possibility is that anchoring salient boundary information in memory provides an entry point for recalling specific episodic events. Supporting this view, participants tend to make nonserial “jumps” to boundary information during recall (DuBrow & Davachi, ; Heusser et al, ). Forward transitions during recall have also been shown to be greater from boundary items than from preboundary items from a recently seen sequence of images (DuBrow & Davachi, ; Heusser et al, ).…”

“…Supporting this view, participants tend to make nonserial “jumps” to boundary information during recall (DuBrow & Davachi, ; Heusser et al, ). Forward transitions during recall have also been shown to be greater from boundary items than from preboundary items from a recently seen sequence of images (DuBrow & Davachi, ; Heusser et al, ). Taken together, these findings suggest that boundary representations form particularly strong memories, thereby providing a strong cue for serial recall as well.…”

“…Faster reaction times to event boundary items were associated with better source memory for the background colors. This finding suggests that greater attention to boundary representations was related to strong source memory binding for those items (adapted from “Perceptual boundaries cause mnemonic trade‐offs between local boundary processing and across‐trial associative binding” by Heusser et al, , Journal of Experimental Psychology: Learning, Memory, and Cognition, 44(7), 1075–1090) [Color figure can be viewed at wileyonlinelibrary.com]…”

“…At the behavioral level, many types of context shifts, including narrative (Zwaan, Langston, & Graesser, ; Zwaan & Radvansky, ), spatial, (Radvansky & Copeland, ), motion (Zacks, ), and other perceptual shifts (Sridharan, Levitin, Chafe, Berger, & Menon, ; Swallow et al, ; Swallow, Zacks, & Abrams, ) have been demonstrated to not only influence how we perceive discrete events but also to influence how we remember the temporal aspects of those prior episodes (Davachi & DuBrow, ; DuBrow & Davachi, , , ; Ezzyat & Davachi, , ; Heusser, Ezzyat, Shiff, & Davachi, ; Horner, Bisby, Wang, Bogus, & Burgess, ; Lositsky et al, ; Sols, DuBrow, Davachi, & Fuentemilla, ; Figure ). For instance, when studying a list of information, items that appear sequentially are more likely to be “bound” together, facilitating memory for the order in which they occurred.…”

“…However, if items appear on either side of an event boundary (e.g., moving from one room to another), their sequential binding is reduced. That is, individuals are more likely to forget the precise order of item pairs if they spanned an intervening context shift (DuBrow & Davachi, , , ; Ezzyat & Davachi, ; Heusser et al, ; Horner et al, ; Sols et al, ). Thus, contextual overlap appears to be important for determining whether incoming information becomes integrated into a unified memory representation.…”