Identification of contrast-defined letters benefits from perceptual learning in adults with amblyopia

Vision Res. 2006 Oct;46(22):3853-61. doi: 10.1016/j.visres.2006.06.014. Epub 2006 Aug 22.


Amblyopes show specific deficits in processing second-order spatial information (e.g. Wong, Levi, & McGraw (2001). Is second-order spatial loss in amblyopia explained by the loss of first-order spatial input? Vision Research, 41, 2951-2960). Recent work suggests there is a significant degree of plasticity in the visual pathway that processes first-order spatial information in adults with amblyopia. In this study, we asked whether or not there is similar plasticity in the ability to process second-order spatial information in adults with amblyopia. Ten adult observers with amblyopia (five strabismic, four anisometropic and one mixed) were trained to identify contrast-defined (second-order) letters using their amblyopic eyes. Before and after training, we determined observers' contrast thresholds for identifying luminance-defined (first-order) and contrast-defined letters, separately for the non-amblyopic and amblyopic eyes. Following training, eight of the 10 observers showed a significant reduction in contrast thresholds for identifying contrast-defined letters with the amblyopic eye. Five of these observers also showed a partial transfer of improvement to their fellow untrained non-amblyopic eye for identifying contrast-defined letters. There was a small but statistically significant transfer to the untrained task of identifying luminance-defined letters in the same trained eye. Similar to first-order spatial tasks, adults with amblyopia benefit from perceptual learning for identifying contrast-defined letters in their amblyopic eyes, suggesting a sizeable degree of plasticity in the visual pathway for processing second-order spatial information.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptation, Ocular / physiology
  • Adult
  • Amblyopia / physiopathology*
  • Anisometropia / physiopathology
  • Contrast Sensitivity / physiology
  • Female
  • Humans
  • Learning / physiology
  • Light
  • Male
  • Middle Aged
  • Pattern Recognition, Visual / physiology*
  • Photic Stimulation / methods
  • Psycholinguistics
  • Psychophysics
  • Sensory Thresholds / physiology
  • Strabismus / physiopathology
  • Visual Acuity / physiology