| Abstract: | In the present study, we examined the hypothesis that perceptual load is the primary factor that determines the efficiency
of attentional selection. Participants performed a visual search task under conditions of high- and low-load. In line with
the perceptual load hypothesis, presenting conditions of highand low-load in separate blocks of trials resulted in processing
of to-be-ignored stimuli only in the lowload condition (Experiment 1). However when high- and low-load conditions were randomly
mixed in blocks of trials, the participants showed processing of to-be-ignored stimuli in both conditions, suggesting that
high perceptual load is not necessarily sufficient to obtain perceptual selectivity (Experiment 2). An analysis of intertrial
transition effects showed that on high-load trials, processing of to-be-ignored stimuli occurred only when the previous trial
was a low-load trial. The results suggest that low perceptual load can engender broad attentional processing. On the other
hand, when a high-load trial was preceded by another high-load trial, little processing of task-irrelevant stimuli was observed.
The present results are discussed in terms of the interaction between expectancies and bottom-up factors in the efficiency
of attentional selection. |
