Abstract
Purpose
Our previous study revealed that during monocular viewing, attentional modulation in V1 to input from the amblyopic eye is degraded, and that this degradation correlates with the magnitude of amblyopic suppression measured behaviorally (Hou et al., 2016). Training adult amblyopes with dichoptic attention tasks improves attentional modulation in V1, which significantly correlates with the reduction of suppression (Hou & Nicholas, 2022). These findings, though based on correlation analyses, suggest a tight relation between amblyopic suppression and selective visual attention. In this study, we investigate whether selective attention can causally manipulate the magnitude of amblyopic suppression.
Methods
We adapted a standard selective attention protocol (Posner, 1980; Carrasco, 2011) to determine whether attentional cueing can manipulate amblyopic suppression using visual psychophysics. We used the same stimuli as in our previous study (Hou et al., 2016) to quantify the magnitude of interocular suppression in amblyopes by estimating the percept of object in the amblyopic eye that is suppressed when an object is presented in the fellow eye. Specifically, we present stimuli (vertical and horizontal bars, consisting of a 1 cpd Gabor) with equal contrast (35%) in each/or one eye viewed through a mirror stereoscope. The length of the bar was adjusted for the amblyopic eye to yield 75% correct or better. The binocular d’ was compared under three cueing conditions within a block: valid cue (40% of trials), neutral cue (40%), and invalid cue (20%) for both the amblyopic eye and the fellow eye.
Results
Our results show that the binocular d’ appears higher for a valid cue in the amblyopic eye compared to the d’ for a neutral and invalid cue. The cueing does not help with the fellow eye.
Conclusions
Our results suggest that selective attention to the amblyopic eye can reduce amblyopic suppression.