investigating-deployment-visual-attention-before-accurate-averaging

Investigating the Deployment of Visual Attention Before Accurate and Averaging Saccades via Eye Tracking and Assessment of Visual Sensitivity

This experimental protocol was designed to investigate whether visual attention is obligatorily deployed at the endpoint of saccades. To this end, we ...

Ludwig-Maximilians-Universität München

Vrije Universiteit Amsterdam

Observers made a saccade between two fixation markers while a probe was flashed sequentially at two locations on a side screen. The first probe was presented in the far periphery just within the observer's visual field. This target was extinguished and the observers made a large saccade away from the probe, which would have left it far outside the visual field if it had still been present. The second probe was then presented, displaced from the first in the same direction as the eye movement and by about the same distance as the saccade step. Because both eyes and probes shifted by similar amounts, there was little or no shift between the first and second probe positions on the retina. Nevertheless, subjects reported seeing motion corresponding to the spatial displacement not the retinal displacement. When the second probe was presented, the effective location of the first probe lay outside the visual field demonstrating that apparent motion can be seen from a location outside the visual field to a second location inside the visual field. Recent physiological results suggest that target locations are "remapped" on retinotopic representations to correct for the effects of eye movements. Our results suggest that the representations on which this remapping occurs include locations that fall beyond the limits of the retina.

Apparent motion from outside the visual field, retinotopic cortices may register extra-retinal positions.

In many situations like playing sports or driving a car, we keep track of moving objects, despite the frequent eye movements that drastically interrupt their retinal motion trajectory. Here we report evidence that transsaccadic tracking relies on trade-offs of attentional resources from a tracked object's motion path to its remapped location. While participants covertly tracked a moving object, we presented pulses of coherent motion at different locations to probe the allocation of spatial attention along the object's entire motion path. Changes in the sensitivity for these pulses showed that during fixation attention shifted smoothly in anticipation of the tracked object's displacement. However, just before a saccade, attentional resources were withdrawn from the object's current motion path and reflexively drawn to the retinal location the object would have after saccade. This finding demonstrates the predictive choice the visual system makes to maintain the tracking of moving objects across saccades. 

Attentional trade-offs maintain the tracking of moving objects across saccades.

Object tracking across eye movements is thought to rely on presaccadic updating of attention between the object's current and its "remapped" location (i.e., the postsaccadic retinotopic location). We report evidence for a bifocal, presaccadic sampling between these two positions. While preparing a saccade, participants viewed four spatially separated random dot kinematograms, one of which was cued by a colored flash. They reported the direction of a coherent motion signal at the cued location while a second signal occurred simultaneously either at the cue's remapped location or at one of several control locations. Motion integration between the signals occurred only when the two motion signals were congruent and were shown at the cue and at its remapped location. This shows that the visual system integrates features between both the current and the future retinotopic locations of an attended object and that such presaccadic sampling is feature specific.

Article	Year
Apparent motion from outside the visual field, retinotopic cortices may register extra-retinal positions. PloS one\| PubMed ID: 23077606	2012
Attentional trade-offs maintain the tracking of moving objects across saccades. Journal of neurophysiology\| PubMed ID: 25609111	2015
Presaccadic motion integration between current and future retinotopic locations of attended objects. Journal of neurophysiology\| PubMed ID: 27385792	2016

Martin Szinte

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