The effect of attention to distractor on inhibitory processes in selective attention

Selective attention has been viewed as a dual- process mechanism, that is, exciting targets and inhibiting distractors. Most early studies concentrated mainly on the target-excitation, whereas recent investigations began to pay more attention to the inhibitory selective attention mecha-nism. A measure named negative priming (NP) was exten-sively employed to probe into the inhibitory processes. The Houghton and Tipper Model put forward a notion: the inhi-bition that feeds back to the distractor is reactive. That means, the level of inhibition is determined by the activation state of the distractor. Distractors that are more salient and intrude into the control of action receive greater inhibitory feedbacks than less salient distractors. Because increasing attention to an object would enhance the early processing of this object, we thus hypothesized that augmenting the level of attention to a distractor might lead to a higher level of inhi-bition, revealed as a corresponding augmentation in the magnitude of NP effect. To test this assumption, an object- based identification task was then applied, and participants were asked to make the animate/inanimate categorization. Attention level was manipulated by varying the relative spa-tial locations of target and distractor (overlapped or sepa-rated). A reliable greater NP effect was found in the over-lapped than separated condition, indicating that distractors under the high-level attention condition (overlapped) got greater initial excitation, and then evoked greater subsequent inhibitory feedbacks, therefore resulting in a larger NP effect. These results provide direct evidence for the reactive inhibi-tion suggested by the Houghton and Tipper model. Mean-while a coincident greater positive priming (PP) effect was obtained under the overlapped than separated condition, which could be attributed to the higher level of target activa-tion in the overlapped condition. The covariation of NP and PP effects further confirmed that the way of our manipula-tion on attention level in this study was valid.