A Role of Eye Vergence in Covert Attention

Maria Solé Puig,J Antonio Aznar-Casanova,Hans Supèr,Laura Pérez Zapata,Susana Martinez-Conde

doi:10.1371/journal.pone.0052955

Maria Solé Puig, J Antonio Aznar-Casanova + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0052955

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Abstract

Covert spatial attention produces biases in perceptual and neural responses in the absence of overt orienting movements. The neural mechanism that gives rise to these effects is poorly understood. Here we report the relation between fixational eye movements, namely eye vergence, and covert attention. Visual stimuli modulate the angle of eye vergence as a function of their ability to capture attention. This illustrates the relation between eye vergence and bottom-up attention. In visual and auditory cue/no-cue paradigms, the angle of vergence is greater in the cue condition than in the no-cue condition. This shows a top-down attention component. In conclusion, observations reveal a close link between covert attention and modulation in eye vergence during eye fixation. Our study suggests a basis for the use of eye vergence as a tool for measuring attention and may provide new insights into attention and perceptual disorders.

Highlights

Humans, like several other animals, have their two eyes positioned on the front of their heads, and provide us with a single visual field
We report the relation between the angle of eye vergence (AoEV) and covert attention
A logical explanation for our results is to consider the distance of the peripheral target location

Summary

Introduction

Like several other animals, have their two eyes positioned on the front of their heads, and provide us with a single visual field. The eyes receive a slightly different projection of the image because of the two eyes’ different positions on the head. When looking at an object, the eyes must rotate around a vertical axis so that the projection of the image is in the center of the retina in both eyes. Vergence refers to the simultaneous movement of both eyes in opposite directions to obtain single binocular vision. The eyes rotate towards each other (convergence) when looking at an object closer by, while for an object farther away they rotate away from each other (divergence). The angle of vergence (AoEV) corresponds to the angle generated when both eyes focus on one point in space (Fig. 1)

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