Abstract
Perceptual learning is gaining recognition as a potentially beneficial treatment for adults with amblyopia. However, it is unclear how consistent the training benefit is across subjects and tasks. We investigated this question in amblyopic non-human primates (Macaca nemestrina). We used an integrative training stimulus: random dot motion direction discrimination over a range of directions and dot speeds. We then tested for improvement in performance on various motion and form tasks post-training: coherent motion detection, Glass pattern form discrimination, contrast sensitivity, and Vernier acuity. As a control, we assessed the untrained fellow eye for any changes in performance. All data were collected using two-alternative forced-choice psychophysical methods. Four amblyopic monkeys, two strabismic and two anisometropic, and one visually-normal control were tested. The number of training trials for perceptual learning ranged from 15,000 – 30,000. Our results showed that 1) at least 20,000 training trials were needed for substantive perceptual learning to occur; 2) in most cases, learning transferred within the training domain to a non-practiced motion task, but there was less transfer across domains, to the spatial tasks; 3) contrast sensitivity improved in one-half of the cases but was poorer after training in the other cases; 4) form discrimination performance was typically poorer after training, with only 1 of the 4 amblyopes showing a clear training benefit; 5) Vernier acuity was mostly unaffected by the training; 6) in several cases, serendipitous improvement in the untrained fellow eye negated any benefit to the amblyopic eye. These results suggest that further evaluation is needed before perceptual learning can be considered a consistent, broadly effective and beneficial treatment for amblyopia.
Meeting abstract presented at VSS 2012