Recent research suggests that bottom-up salience determines attentional priority only when subjects adopt the strategy of searching for a discontinuity (singleton-detection mode). In contrast, bottom-up salience is held to play no role in visual search when subjects look for a known-to-be-relevant target feature (feature-search mode). This conclusion is based on the finding that within the feature-search mode, a singleton distractor captures attention to its location only if it possesses the target feature. However, in such studies, only top-down factors (whether or not the distractor possessed the target feature) were manipulated, while bottom-up factors were kept constant, as the distractor was always a singleton. Thus, while these findings suggest that salience has no effect on performance outside the attentional set adopted by the observer for a specific feature, it remains possible that salience may enhance attentional priority within this set. This question was explored in two experiments by investigating whether or not a distractor possessing the target feature is more difficult to ignore when it is a singleton (high bottom-up activation) than when it appears within a heterogeneous background (low bottom-up activation). A distractor possessing the target feature produced stronger capture when it was salient, but only early in processing. Moreover, a singleton distractor outside the attentional set was inhibited rather than simply ignored. These results suggest that bottom-up salience plays a role within the feature search mode, and that overriding capture by an irrelevant singleton results from inhibiting this singleton's salient feature rather than from ignoring salience per se.
ASJC Scopus subject areas
- Sensory Systems