Abstract:

The degree to which involuntary allocation of attention is influenced by top-down set has been a topic of debate during the last 20 years. According to contingent attentional capture theory, the initial allocation of attention is conditioned on top-down attentional control settings (ACSs), such that stimuli that do not match those settings will not elicit an involuntary attention shift. According to attentional disengagement account, in contrast, attention is always initially allocated to salient stimuli, and the effects of ACSs simply reflect the speed at which attention is disengaged from an irrelevant stimulus. We proposed that attentional capture effect of unmatched cue depends on the strength of ACS. When ACS is weaker, unmatched cue tends to capture attention, but when ACS is strong enough, it tends to be suppressed. The mechanism of the attentional capture was also explored. In addition, two types of exogenous cues (color singleton cue and onset cue) with the same task (or ACS) were compared; whether onset cue and color singleton cue might be modulated differently by ACS was also investigated. The present study was designed to explore the mechanisms involved in attentional capture phenomenon in the spatial-precuing paradigm. In Experiment 1, each participant looked for the color singleton target or onset target throughout the entire block. We supposed such a task involved a weaker ACS. In Experiment 2, each participant looked for a red or white feature target, which forced the participants to maintain a strong ACS level. In Experiment 3, go/no-go paradigm was used to make participant set up a stronger ACS. Red and white feature targets presented changed unpredictably on a trial-by-trial basis; participants were required to respond to red feature targets and suppress their response to white feature target. In all experiments, a spatially non-predictive color singleton cue or onset cue would appear before the display of the targets; the probabilities of the presence of these two types of cues were equal. The cue at the predicted target location was at a chance level; there were two types of cue–target location: valid (the target appeared at the cued location); invalid (the target appeared at an uncued location). In Experiment 1 and 2, cue-to-target stimulus onset asynchrony (SOA) was set at 150 ms. In order to better reveal the underlying mechanism of attentional capture, SOAs were set at 150 ms and 600 ms in Experiment 3 to explore how the effect of capture changed with time. Our results showed that in Experiment 1, in the color singleton searching task, both matched color singleton cues and unmatched onset cues could capture attention and that the magnitude of capture effects of matched color singleton cues was larger than that of onset cues. In the onset searching task, only matched onset cues could capture attention; color singleton cues could not capture attention. In Experiment 2, it was shown that both matched color singleton cues and onset cues could capture attention. However, when unmatched color singleton cues were suppressed, unmatched onset cues could not capture attention. In Experiment 3, go and matched color singleton cues could capture attention, but the magnitude of capture effects under longer SOAs was smaller than that under shorter SOAs. When no-go and unmatched onset cues were suppressed, the magnitude of suppression effect was not significant under shorter SOAs, but was significant under longer SOAs. The present findings demonstrated that (1) ACS operated through disengagement of attention from featured locations that did not match ACS and suppressing the location afterwards, which supported attentional disengagement account, (2) The overall pattern of results showed that the mechanisms for attention capture for the onset cue and color singleton cues were the same. However, But in comparison with color singleton cues, unmatched onset cues can capture attention more easily, and were more difficult to be suppressed in the same search task.

Key words: attentional capture, attentional control set, contingent capture account, search mode, attentional disengagement account