Role of Visual Hemifields in Processing and Storage of Motion Information

Date

2016-12

Journal Title

Journal ISSN

Volume Title

Publisher

Abstract

PURPOSE: Studies on motion processing using multiple-object tracking indicates that the bottleneck of information processing occurs at the visual-short term memory (VSTM) stage. In contrast, recent studies reported the bottleneck to occur prior to VSTM at the stimulus encoding stage. Performance in motion processing is greatly influenced by attention to the task. On the other hand, studies on attention, e.g. Alvarez and Cavanagh (2005), suggest that there are partial or independent resources for attention across each visual hemifield. The purpose of this study was to investigate, using a cross-cuing approach, whether attentional resources are partial or independent in motion processing across different memory stages.

METHODS: In the first (N=9) and second experiments (N=8) observers reported the direction of motion of a target through a partial-report technique where the target’s terminal position was cued. The targets were distributed equally and either confined to one hemifield (unilateral) or both visual hemifields (bilateral). The cue was presented either immediately after the stimulus presentation, or with a delay that ranged from 50 to 3000 ms to investigate the processing of motion across stimulus encoding, sensory, and VSTM stages. A third experiment (N=8) was designed to replicate the findings of Alvarez and Cavanagh.

RESULTS: At the stimulus encoding stage, performance gradually declined (30%) as a function of set size but there was no statistical significance between the unilateral and bilateral conditions. At the sensory memory and the VSTM stages, the main effect on performance was due to set size. Again, there was no effect on performance due to the visual-field location of the targets. In the third experiment, performance in the bilateral and unilateral conditions was similar and with no statistically significant difference.

CONCLUSIONS: I did not find any evidence for independent attentional resources for each hemifield in processing the direction of stimulus motion. The results of this study support findings of previous studies that the bottleneck of motion processing occurs prior to VSTM, at the stimulus-encoding stage.

Description

Keywords

Motion processing, Attention, Multiple-object tracking, Memory, Hemfield

Citation