Sexs chat online gratuit - Spatial updating and the maintenance of visual constancy
Nevertheless, one factor may explain the conflict in these results.
We used a trans-saccadic cueing paradigm in which the relevant positions could be defined or not by visual objects (simple square outlines).
We find an attentional benefit at the spatiotopic location of the cue only when the object (the placeholder) has been continuously present at that location.
In this case, with objects always present, we expected to find facilitation at the spatiotopic location regardless of the probe delay (0 or 400 ms)..
One of four locations was cued (centrally with a small black square, see panel c for a representation of the cue); the fixation cross moved and participants executed a saccade to its new location.
The results showed a persisting attentional benefit at the retinotopic (eye-centered) coordinates of the cued location (even though task irrelevant) for 100–200 ms after an eye movement, along with growing facilitation at the spatiotopic location, reaching its maximum around 400 ms after saccade completion (see Casarotti, Lisi, Umiltà, & Zorzi, , for simulations with a computational model that implements a spatial updating process).
Neural signatures of this persisting retinotopic trace have been studied with EEG and f MRI for several different areas in human visual cortex (Golomb, Nguyen-Phuc, Mazer, Mc Carthy, & Chun, ); conversely, attention lingers at the retinotopic location and is found only later at the spatiotopic location (Golomb and colleagues).
A number of review papers have suggested that the remapping process offers a sparse form of visual constancy by predicting where targets will be in retinotopic coordinates following each eye movement (Berman & Colby, ).
However, other studies report that attention is updated slowly after the eye movement and that initially, attention remains in the retinotopic location despite the fact that this location is behaviorally irrelevant following the saccade (Golomb, Chun, & Mazer, ).
We examine whether the presence of a visual object at the attended location could support the maintenance of voluntary attention in spatiotopic coordinates across eye movements, and thereby reconcile the conflicting findings on this debated topic.
In the first experiment, we designed a simple trans-saccadic spatial cueing paradigm to investigate how saccades affect covert orienting to a visual object that remains present throughout.
Recent studies have shown that attentional facilitation lingers at the retinotopic coordinates of a previously attended position after an eye movement.Tags: Adult Dating, affair dating, sex dating