Abstract:

There is large amount of evidence showing that the saliency of a stimulus on a dimension (singleton) can involuntarily capture attention. Previous work has also demonstrated that attentional capture induced by feature singleton is modulated by top-down factors. For example, the semantic relationship between target and distractors impacts on the capture of attention; search strategies (Singleton Detection Mode and Feature Search Mode) are another potential factors affecting attentional capture. Here we measured how these factors guided attentional capture in a visual search task by manipulating cue-target relevance and search strategies and attempted to provide systematically evidence on capture of attention. A modified spatial cueing paradigm was employed in the current study. In a trial, a fixation screen was presented for 500 ms, followed by an uninformative red cue which appeared for 100 ms. Then a fixation screen was showed for 100 ms, followed by a target screen with Chinese characters surrounding by squares displayed 1000 ms. Participants had to make a judgment for the gap orientation of a target square while ignoring other distractors. Targets were Chinese characters randomly presented at the cued or non-cued locations, making cues valid or invalid. The effect of attentional capture referred to the fact slower responses to invalid contrasting to those to valid targets. The magnitude of the effect was computed to assess the effect size across different experimental conditions. In the current study, there were ten experimental conditions according to various combinations of perceptional relevance, semantic relevance between cue and target and singleton detection mode and feature search mode. The order of experimental conditions was counterbalanced across participants. As a result, the capture effect was not observed when cue and target were irrelevant whilst no search strategy was adopted, but feature search mode was induced. However, the capture effect was observed when singleton detection mode was used, and when the semantic relevance between the cue and the target was established. The capture effects were also reliable significant when there was the perceptional relevance between the cue and target. In contrast, the capture effects induced by singleton detection mode and by semantic relevance were eliminated when perceptional relevance occurred. It was concluded that (1) the perceptional relevance between cue and target was more pronounced to drive attentional capture than the semantic association between cue and target and search strategies, (2) although the latter was also able to modulate the magnitude of attentional capture, but the effect exclusively occurred when there was no perceptional relevance between cue and target. (3) attentional capture was modulated by the search strategy - singleton detection mode, but not by feature search mode after controlling the perceptional relevance and the semantic relevance between cue and target.

Key words: perceptional relevance, semantic relevance, singleton detection mode, feature search mode, attentional capture