The relationship between spatial pooling and attention in saccadic and perceptual tasks

Abstract

Saccades aimed at spatially extended targets land reliably at central locations determined by pooling information across the target shape [Melcher, D., & Kowler, E. (1999). Shape, surfaces and saccades. Vision Research, 39, 2929-2946; Vishwanath, D., & Kowler, E. (2003). Localization of shapes: Eye movements and perception compared. Vision Research, 43, 1637-1653]. Previous findings of saccadic errors when attempting to look at a target in the midst of distractors encouraged suggestions that pooling occurs indiscriminately, with little or no influence of a selective filter to eliminate the influence of nearby distractors. To determine the effectiveness of filtering, saccadic localization was studied for saccades made to a set of target elements (discs) interleaved with an equivalent set of distractors of a different color. With such interleaved elements, selection and spatial pooling are constrained to occur over the same spatial region. The results showed that filtering was effective and saccadic landing position was determined mainly by the target elements. Concurrent perceptual judgments made about the same stimuli (estimating the mean size of either target or distractor discs) showed better performance for the target discs than distractors, confirming that perceptual attention was allocated to the set of target elements. These results: (1) support the role of attention in setting the input to the spatial pooling process that guides saccades to spatially extended targets, and (2) show that perceptual judgments of mean value, often thought to impose modest attentional demands, are not immune to the constraints of this pre-saccadic filter.

Eye fixation during multiple object attention is based on a representation of discrete spatial foci

“…Since resolution decreases with eccentricity from fixation, the optimal gaze position is the centroid of the selected spatial regions, a prediction supported by the finding that saccade size correlates better with the distance of the centroid of selected targets than the centroid of targets plus intervening distractors30. By comparing fixation to multi-target geometries which yield different centroid predictions for the three different models of spatial selection (Fig.…”

Eye movements: The past 25years

“…), but more recent work has shifted the responsibility for averaging to the operation of a selective filter that was not given either the time, or the visual cues, to find the target before the saccade was launched. This shift in view was prompted by findings that saccades became more accurate (less influence of the surrounding non-targets) when more time was allowed for target selection to occur (Ottes, Van Gisbergen & Eggermont, 1985; Cöeffé & O’Regan, 1987; Cohen, Schnitzer, Gersch, Singh & Kowler, 2007), or when cues or instructions were given to signal where the saccade should land (He & Kowler, 1989, 1991; Findlay & Blythe, 2009). These considerations show that center-of-gravity saccades are no different from any saccade: they direct the line of sight to the attended region.…”

Looking at the center of the targets helps multiple object tracking

“…Previous work found that when participants made saccades to a group of peripheral targets, the saccadic endpoint landed near the center of the target group, both when the targets were alone and amidst differently colored distractors (Cohen, Schnitzer, Gersch, Singh, & Kowler, 2007; McGowan, Kowler, Sharma, & Chubb, 1998). However, unlike the stationary target groups employed previously, we have investigated eye movements during MOT in which targets move and can only be distinguished from distractors via accurate attentive tracking.…”