Academic journal article Attention, Perception and Psychophysics

Perceptual Load Modulates the Processing of Distractors Presented at Task-Irrelevant Locations during the Attentional Blink

Academic journal article Attention, Perception and Psychophysics

Perceptual Load Modulates the Processing of Distractors Presented at Task-Irrelevant Locations during the Attentional Blink

Article excerpt

The distribution of attention in both space and time is critical for processing our dynamic environment. Studies of spatial attention suggest that the distribution of attention is decreased when the perceptual load of a task increases, resulting in decreased processing of task-irrelevant distractors. Studies of the attentional blink (AB) suggest that the temporal distribution of attention also influences distractor processing, such that distractor processing increases during the AB relative to outside the AB (Jiang & Chun, 2001). Two experiments are reported in which the extent to which the difficulty of the first target task (T1) modulates the processing of task-irrelevant distractors during the AB was tested. To investigate this issue, both the first and second target tasks (T1 and T2) required identifying a central stimulus that was flanked by low-load or high-load distractors. Consistent with previous studies of the AB, there was evidence of more distractor processing during the AB than outside the AB. Critically, however, the interference caused by distractors presented simultaneously with T2 during the AB was reduced when T1 perceptual load was high relative to when it was low. These results suggest that increasing T1 perceptual load decreases distractor processing during the AB and that perceptual processes influence both the temporal and spatial distribution of attention.

Survival in a complex and dynamic environment requires the ability to selectively attend to task-relevant information while ignoring distracting task-irrelevant information. Although people are effective at maintaining attention to specific tasks, disruptions of selective attention commonly occur. Laboratory studies suggest that the efficacy of selective attention is modulated by the structure of a task and the demands that it places on perceptual and cognitive systems (Lavie, 2005; Pashler, 1998; Vogel, Woodman, & Luck, 2005; Yantis & Johnston, 1990). For instance, increasing the difficulty of a task by increasing the visual similarity between a target and the surrounding distractors can lead to reduced behavioral interference and neuronal responses evoked by task-irrelevant distractors, indicating an increase in the selectivity of attention (Handy & Mangun, 2000; Handy, Soltani, & Mangun, 2001; Lavie, 1995; Lavie, Hirst, de Fockert, & Viding, 2004). Other studies indicate that the reduced influence of task-irrelevant distractors that occurs with increased perceptual similarity is not due to generalized increases in task difficulty, because increasing the difficulty of a task by requiring participants to hold more information in working memory can lead to increased behavioral interference and increased neural activity evoked by task-irrelevant distractors, indicating a decrease in the selectivity of attention (de Fockert, Rees, Frith, & Lavie, 2001; Lavie et al., 2004). Thus, depending on the structure of the task and the demands placed on different perceptual and cognitive systems, the selectivity of attention can be increased or decreased.

Changes in the selectivity of attention that occur with task demands have been explained by several models that propose multiple selective attention mechanisms that operate at different stages of processing (Lavie, 2005; Pashler, 1998; Vogel, Luck, & Shapiro, 1998; Vogel et al., 2005; Yantis & Johnston, 1990). For instance, according to one of these models, commonly known as the load theory of selective attention (Lavie, 2005; Lavie et al., 2004; Lavie & Tsal, 1994), information processing is performed by two resource-limited stages. The first stage consists of the perceptual processing system; the second stage is composed of the cognitive control system. At the perceptual stage, resources are allocated automatically and exhaustively, with priority given to processing information that is consistent with the current task set (i.e., task-relevant information). …

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