Bahar Aykut¹ (bahar.aykut@sabanciuniv.edu), Nihan Alp¹; ¹Sabanci University, Istanbul

A core challenge for perception and memory is organizing continuous streams of input into meaningful units. Prior research has shown that changes in perceptual context (frame color) or semantic content (category) influence how we structure experience. For example, changes in frame color can act as a visual context shift, grouping or separating information. In parallel, semantic changes are known to create event boundaries that often disrupt temporal memory. However, naturalistic studies frequently conflate perceptual context and semantic content, and controlled paradigms rarely incorporate broader category change. Here, we investigated how perceptual context and semantic content (broader object categories such as animals or tools) interact to shape temporal memory. Participants (N = 23) viewed sequences of real-world objects in colored frames, where color and category changed separately (only color or only category) or simultaneously (both changed at the same time). Later, participants completed the temporal-order and temporal-distance judgment tasks. The results showed that perceptual context shifts driven by color changes significantly impaired temporal-order accuracy relative to a within-context baseline, suggesting that perceptual context changes may trigger an attentional reset that disrupts temporal associations. Crucially, the presence of semantic content change -whether alone or simultaneously with perceptual context- enhanced temporal-order accuracy, despite eliciting significantly longer reaction times and increased subjective temporal-distance judgments. These findings reveal a distinction between boundary types, indicating that not all boundaries might function identically in temporal memory. Semantic content provides a higher-level schematic scaffold that enhances temporal organization, serving as a cognitive landmark that effectively helps segment the timeline into distinct groups. However, in the absence of semantic content change, perceptual context shifts disrupt temporal continuity, perhaps by interfering with temporal association. Our findings highlight how multiple sources of organization -both perceptual and semantic- modulate how we group, segment, and remember continuous streams of input.

Acknowledgements: N.A. is supported by Scientific and Technological Research Council of Turkey (TUBITAK 1001) under the Grant Number 122K922. The authors thank to TUBITAK for their supports.