Seonbeom Heo (), Jonga Kwon, Suk Won Han, Sohyun Kim; ¹Department of psychology, Chungnam National University

Abrupt onsets are known to capture attention automatically, but the processing stage at which they interfere with task performance remains unclear. This study examined whether interference from task-irrelevant abrupt onsets arises at perceptual or post-perceptual stages, and whether this depends on search mode. Each participant performed one of two visual search tasks: an orientation search (a tilted line among vertical lines), which tends to proceed in a parallel manner, and a T/L search (a rotated T among rotated Ls with offset junctions), which requires serial shifting of attention among the search stimuli. In both tasks, the search display was briefly presented (75 ms), straining the perceptual processing of search stimuli. Importantly, in half of all trials, a green outlined square was presented at a non-target location prior to the search display, while in the other half, no such onset distractor was presented. Under this perceptually challenging condition, changes in response accuracy and speed were measured as indicators of perceptual and non-perceptual modulations, respectively. As results, In the parallel search task, the presentation of an abrupt onset significantly increased RT (p < .001), but did not affect accuracy (p = .826), indicating post-perceptual interference. By contrast, in the serial search task, the abrupt onset significantly reduced accuracy (in baseline around 80%) and increased RT (p < .001), indicating disruption at the perceptual stage. These findings demonstrate that the locus of attentional capture by abrupt onsets depends on task demands; interference is confined to response-level processes during parallel search, but extends to perceptual encoding during serial search. This task-dependent dissociation helps reconcile mixed results in the literature and underscores the importance of search mode in shaping the impact of exogenous attention.

Acknowledgements: This research was supported by the National Research Foundation grant (NRF) funded by the Korea government (No. NRF-2024S1A5A2A01019821)