Abstract
Whilst a large body of evidence has demonstrated the effects of covert attention on spatial processes, much less is known about attentional effects on the complementary temporal aspects of visual perception. We examined the effects of spatial attention on temporal integration using the Ternus display. In a typical Ternus display horizontally aligned disks are shifted by one position across alternating frames that are separated by a varying inter-frame interval (IFI). This display can induce different motion percepts (element and group motion). Element-motion is thought to reflect temporal integration while group-motion reflects spatial integration.
Experiments 1 and 2 employed peripheral presentation (5° eccentricity) of a typical Ternus- display with different attention manipulations. In Experiment 1 sustained attention was manipulated via the degree of certainty regarding the disks location. In the attended condition, the disks appeared always in the same location, and in the unattended condition they could appear in one of two possible locations. Observers indicated which motion they perceived. We found higher rates of element-motion reports in the attended condition than in the unattended condition, suggesting that sustained attention enhances temporal integration. In Experiment 2 a peripheral cue was used to generate transient spatial attention. We found no attentional effect on the Ternus motion percepts. In Experiment 3 we examined whether the lack of effect in Experiment 2 was due to unintended temporal interactions between cue related transients and the IFI manipulation. We used a modified Ternus display with no IFI manipulation and Gabor patches as elements. Temporal integration was manipulated by varying the elements’ orientation similarity across display frames. The patches’ orientation varied between the two frames from 0° to 45°. We found higher rates of element motion reports in the attended condition, suggesting that transient attention, like sustained attention, can enhance temporal integration.