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Yue Zhang, Natalya Shelchkova, Rania Ezzo, Martina Poletti; Exogenous Attention and Inhibition of Return in the Foveola. Journal of Vision 2020;20(11):843. doi: https://doi.org/10.1167/jov.20.11.843.
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The effects of exogenous attention in the visual periphery have been studied extensively. Yet, it is not well-known if this type of attention can be fine-tuned in the foveola, the 1-degree foveal region where visual resolution is the highest. Here, we addressed this issue by investigating the temporal dynamics of foveal inhibition of return. This phenomenon is typically associated with exogenous attention, and involves the suppression of a stimulus that had been recently attended to.
A classic spatial cueing paradigm was used. The entire stimulus array was scaled in size to fit within the 1-degree foveola. Observers (n=9) fixated on a central marker throughout the trial. After a brief exogenous cue, high-acuity stimuli, tiny bars tilted 45 degree, appeared at four locations 11’ away from the central marker. Following a variable inter-stimulus interval, a response cue appeared pointing to one location. Subjects were instructed to determine the orientation of the stimulus previously presented there. Trials had 50% probability of being valid, i.e., when the exogenous and response cue matched. To eliminate the confounding factor of fixational eye movements, which would otherwise shift the stimulus array on the fovea, we used retinal stabilization; we used retinal stabilization; the stimuli remained immobile on the retina, and only trials without microsaccades were selected for analysis.
Our findings show that for shorter inter-stimulus intervals (~60 ms), subjects’ ability to discriminate fine details was enhanced at the attended location and reduced at the unattended locations (d’ difference between valid and invalid trials; 0.49, p<0.01). We also report a temporal modulation resembling inhibition of return, characterized by higher performance at the unattended locations with longer intervals (d’ difference between valid and invalid trials; -0.61, p<0.01). These results indicate that involuntary attention can be fine-tuned at the foveal scale, contributing to the enhancement of high-acuity vision.
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