Parallel or clump-wise serial? A reinterpretation of feature-search mode.

A central debate in visual attention concerns whether selection is guided primarily by top- down control or by bottom-up salience. In the additional singleton task, the absence of attentional capture by a distractor is often attributed to the adoption of feature-search mode. An alternative account proposes that these displays instead partly induce serial search, which naturally limits distractor interference. The present study tested this by linking two diagnostics of search dynamics, set size effects and two target compatibility, within the same paradigm. Participants searched for a predefined target among heterogeneous non-targets while set size and the presence of a salient color singleton distractor were manipulated. Across two experiments, search showed reliable display size effects and responses were faster when two targets were present than when only one target was present. At larger display sizes no target compatibility effect was observed. At the same time the distractor did not capture attention and instead produced a distractor benefit. Together, these findings indicate that displays commonly assumed to induce the feature-search mode partly require serial selection. The absence of attentional capture therefore reflects sequential serial processing rather than top-down suppression. OPEN PRACTICES STATEMENT: All experiment code, analysis code, and anonymized trial-level participant data are available via the Open Science Framework at: osf.io/g6avc. None of the experiments herein were preregistered.