Context familiarity speeds up boundary responses at encoding

In event segmentation, a context shift (event boundary) commonly leads to slower response times, compared to response times for actions occurring away from boundaries. This effect is commonly considered to result from novelty and segmentation processes in working memory. It is less clear if and how familiarity affects boundary processing. In the current study, we investigated the role of contextual familiarity in boundary processing. Participants saw lists of random pictures while simultaneously listening to sound contexts that changed after each triplet of pictures and rated for each picture how much they thought it was associated to the context. Contextual familiarity was manipulated by replaying one of the sound contexts three additional times throughout a list. During list presentation, participants showed increasingly faster boundary response times for each repetition of the sound context, compared to novel contexts. This effect was not due to merely playing more contexts over time. Participants showed no boundary-related effect in the associative ratings. A subsequent temporal order memory task showed no effect of context familiarity on memory performance, suggesting boundary-related processing and event memory formation may depend on partly independent processes.