Abstract
Amblyopia is a cortical visual disorder caused by unequal visual input from the two eyes during development. Amblyopes show reduced visual acuity as well as more “global” perceptual losses, such as figure-ground segregation and global form integration. We tested the hypothesis that these losses are due to deficiencies in attentional processing, such that attentional selection favors the better eye. We conducted two studies with amblyopic and visually-typical, 5–10 year old children. First, we used a classical endogenous spatial cueing paradigm to test the children on a shape discrimination task. We found that amblyopic children have intact attentional capacity; there were no significant differences between the performance of visually-typical and amblyopic children, or between the fellow and amblyopic eye of amblyopes. A valid cue improved accuracy and decreased reaction time in all cases, compared with a neutral cue condition. Since attentional capacity was normal in amblyopic children, we then asked whether cueing attention could negate amblyopic deficits in global form perception. Again, using a classical spatial cueing paradigm, we asked whether an attentional cue could improve children’s performance on a contour integration task. The task was to discriminate the orientation of an embedded Gabor contour in one of four stimulus patches filled with randomly-oriented Gabors. The child had to select the contour orientation that matched what had appeared at the patch location indicated by a post-stimulus-presentation cue. We found that all children, despite visual condition, benefitted from attentional cueing: they performed significantly better on trials with a valid cue than with a neutral, uninformative cue. Response latency and accuracy both improved as a result of the valid cue. The results show that attentional cueing improves task performance in amblyopic as well as typical children and may be useful in improving higher-order global form perception in amblyopia.
Acknowledgement: Research to Prevent Blindness