Feature-based attentional influences on the accommodation response

Abstract

Accommodation is known as the process by which the vertebrate eye changes optical power to maintain focus on an object as its distance varies. This process is considered as an oculomotor reflex which is controlled by the Edinger-Westphal nucleus. Afferent limb of the neural circuit of accommodation also involves the visual association cortex which is responsible for complex visual processing. It has been shown that visual imagery and concurrent mental activity can modulate accommodative response. In the present study, we investigate possible effects of covert attention on accommodation response. We tested the hypothesis that covertly attending to a moving object could modulate accommodation. We used an autorefractor in a custom made setup to measure the accommodation of the human eyes. The subjects have been instructed to fixate on the center of the infrared camera, while attending to a linearly moving target in their peripheral visual field. They were asked to report the position of the target by pushing a button when it crossed certain markers. We found that the accommodation was significantly altered from the baseline at the moments of focused attention, although there was no displacement of the fixation point. We confirmed that the subjects have not made saccades to the moving target by analyzing the gaze direction. It has been shown extensively that higher cognitive functions of the brain such as visual attention could change the pupil size and dynamics. We provided further evidence that attentional state is reflected in the accommodative response. These findings could shed light on the mechanisms and neural circuits of accommodation and oculomotor system. Moreover, our finding could provide a new behavioral tool to monitor attentional state when pupil dynamics are not reliable. Next steps in this study would be measuring different feature-based attentional effects on multiple accommodative states of the eye.

Meeting abstract presented at VSS 2016