Modulation of Attentional Capture by Display Probabilities in Visual Search

Attentional capture is often thought to be automatic and not modulable. For example, visual search experiments showed that salient distractor singletons strongly capture attention even when they had to be ignored by the observers. Recently, however, it was shown that attentional capture can be modulated by varying the display probability of distractors. Thus, attentional capture is not completely automatic. Distractor singletons in these studies were defined by salient colour differences and, hence, the parvocellular system may have been primarily involved. Here, we aimed at involving the magnocellular system by presenting onset distractors--ie, distractors displayed after the onset of the other search items--which are known to strongly capture attention. Eye movements were recorded. The results clearly show that attentional capture by the onset distractors strongly depended on their display probability: The higher the display probability, the lower the proportion of saccades to the onset distractors. This result provides further evidence that attentional capture is not completely automatic