Abstract:

In visual search, the phenomenon that attention is attracted by task-independent salient stimulus, which leads to search efficiency reduction is called attentional capture. In the traditional theories of visual attentional capture, stimulus-driven theory and goal-driven theory were argued for nearly 20 years. According to stimulus-driven theory, attention is automatically captured by physically salient objects, and regardless of the intentions of the observers. Other researchers believe that only stimuli that match the features of the search target will capture attention. In recent years, two new hybrid models were proposed, which combined bottom-up capture and top-down control settings, called rapid disengagement hypothesis and signal suppression hypothesis. The main content of the rapid disengagement hypothesis is that a salient distractor can always capture attention in a bottom-up manner, but attention only landed on the position of the highlighted stimulus that similar to the target. If the selected stimulus does not look like the target at all, disengagement from that location would be fast and swift. In the empirical evidences of the rapid disengagement hypothesis, spatial-cueing paradigm and oculomotor disengagement paradigm were most often adopted. In those tasks, participants usually took a singleton search strategy to promote search. The signal suppression hypothesis posits that a salient object can automatically produce a bottom-up “attend-to-me” signal, but this signal can be suppressed via top-down control processes when the highlighted object does not meet the task requirements. In the empirical evidences of the signal suppression hypothesis, an additional singleton paradigm was most often adopted. In those tasks, participants were forced to take a feature search strategy. The rapid disengagement hypothesis and the signal suppression hypothesis are indispensable components of the theories of attentional capture, and there are both similarities and differences between them. The similarity lies in the fact that both two theories assume that the initial stage of the attention capture occurs automatically. However, there are different opinions about the shifting of attention during this initial stage. The rapid disengagement hypothesis holds that there is an attention shift in the initial stage of the processing of the salient stimulus, and when the attention has enough time to disengage from the highlight stimulus that does not match the target, attentional capture will not occur. Different from the above views, the signal suppression hypothesis believes that there is no attention shift in the initial stage of the highlight stimulus processing. Attention capture does not actually occur because the salience signal can be suppressed by a top-down mechanism when the salient stimulus is inconsistent with the target. Future researches would focus on the following aspects: (1) More studies adopting different stimuli and experimental methods are needed to support rapid disengagement hypothesis and signal suppression hypothesis; (2) The effects of reward and training on “attentional capture-disengagement” and “signal-suppression” should also be explored in future researches; (3) The neural bases of reactive inhibition mechanism and active inhibition mechanism that involved in rapid disengagement hypothesis and signal suppression hypothesis is a problem which deserves attention.

Key words: visual attentional capture, rapid disengagement hypothesis, signal suppression hypothesis