Attentional capture refers to a phenomenon that irrelevant stimulus involuntarily receive attentional priority. Concerning the driven source of attentional capture, early researches proposed that attentional capture is a completely bottom-up, stimulus-driven process. However, with the deepening of related researches, a large number of researchers believed that attentional capture is modulated by the top-down attentional control settings, and accordingly they proposed the contingent attentional capture theory. In this theory, the attentional control settings limit attention to each feature dimension of the target of current task. The contingent attentional capture theory is supported by a large amount of studies and has been a research focus in attention for several years.
So far, among feature-based contingent attentional capture studies, the targets in all experimental designs have been go signals. Participants were required to respond to such go targets and set up attentional control settings pointing to the feature of the go targets. Despite the importance of the go signals, in the living space there is another kind of visual stimuli that shouldn’t be ignored: the stop signals. In life, we need to constantly adjust our behavior to adapt to changes in the environment, and one of the most important adjustment we take is to inhibit current behavior according to stop signals. Such condition is necessary to a successful inhibition as stop signals receive attentional priority. Therefore, practically the mechanism of attentional selection on stop signals is an important research field involving human survival and adaptability; from the perspective of theoretical research, the contingent attentional capture based on the feature of the stop signal is a critical supplement to both attentional capture and response inhibition theory because the former lacked attempts to set up attentional control settings based on the stop signals while the latter lacked focus on the attentional process on the stop signals.
In summary, this study focused on how contingent attentional capture interact with the feature of stop signals, and was designed to examine: (1) whether the attentional control settings based on the feature of stop signals could be set up; (2) the time characteristics of such attentional control settings should (1) be true; (3) the ERP characteristics of such attentional control settings should (1) be true.
In the first study, we combined the spatial cuing paradigm and the stop-signal task, created a new paradigm for the exploration of the attentional capture based on the color feature of stop signals. In addition to the original go trials in the spatial cuing paradigm, the new paradigm included stop trials in which the target (go signal) and the stop signal were presented simultaneously. The two experiments in the first study proved that the task irrelevant cues with the color of the stop signals captured attention in a top-down way, and this attentional capture effect was not due to the frequency and the luminance difference between the stop signal color and neutral color. Further, this attentional capture effect was not limited within certain color combinations. The first study also revealed that cues with the color of the stop signal debased the overall reaction speed and accuracy of targets.
In the second study, we measured the stop-signal-color-based attentional capture effect under different SOAs and tested whether there were inhibition of return in longer SOA. The results showed that there were cueing effect for both reaction time and error rate in the stop-signal-color cue condition in 108ms SOA and 624ms SOA. The debasement, caused by the stop-signal-color cue, for the overall performance of targets were significantly weakened when SOA was 624ms. When SOA was 1200ms, there were neither cuing effect nor inhibition of return in the stop-signal-color cue condition, and the stop-signal-color cues had no effect on the performance of targets.
In the third study we implemented an ERP experiment to examine the N2pc effect elicited by the stop-signal-color cues. The behavioral results largely replicated what we got in the first study. The stop-signal-color cues elicited an N2pc effect in a time course of 180ms to 250ms after its onset, indicating that attentional resources were allocated to the position of the stop-signal-color cues.
These findings suggest that (1) attentional control settings could be built based on the color feature of stop signals; (2) the attentional capture effect modulated by such attentional control settings could occur at 108ms SOA and 624ms SOA; (3) the stop-signal-color cues could elicit N2pc effect.