The Modulation Of Perceptual Load And Preview Information In Guiding Selective Attention

Visual attention is essential for selecting relevant information and filtering out irrelevant information from cluttered visual scenes. Theory of perceptual load proposes that the extent to which irrelevant distractor can be prevented from processing critically depends on the perceptual load involved in the current task. Distractor can only be ignored under high load condition where relevant processing exhausts capacity-limited attentional resources. Moreover, guided attention allows the observer to use top-down information to prioritize selection of relevant display items, raising the efficiency of visual search.The present study aimed to investigate the impact of preview information upon distractor interference under different perceptual load and further explore the interaction between perceptual load and guided attention. Using a response competition paradigm, participants were asked to identify the target letter in the central search array while trying to ignore a peripheral distractor. Perceptual load was manipulated by varying homogeneity along the shape of relevant items. In addition, color information about the distractor or target was provided. The flanker congruency effects, denoted by incompatible distractors relative to compatible distractors, were contrasted in different target-distractor color match conditions to measure the role of preview information in guiding selective attention.Four experiments were involved in the present study. Different levels of perceptual load were manipulated independently between experiments. The results of Experiment 1 and 2 suggested that in low load condition, flanker congruency effects were equally significant on both color match level and color mismatch level, regardless of whether preview information was provided about the distractor or the target. The results of Experiment 3 and 4 suggested that in high load condition when preview information was provided about the target, flanker congruency effects were significantly increased on color match level relative to color mismatch level. Furthermore, this difference didn’t result from the existence of preview information leading to a reduction of perceptual load for set size.The main findings of this study are generalized as follows:1) The role of preview information in guiding selective attention consists in augmenting the target-related signal, rather than inhibiting the distractor-related noise.2) Under low load condition, the preview information provided can’t guide attention to prioritize those items which match the target-related feature; the processing mode of attention is parallel.3) Under high load condition, the preview information provided can guide attention to prioritize those items which match the target-related feature, thus making visual search more efficient; however, this guidance may also make an observer vulnerable to certain distractors.