title: Learning to identify near-threshold luminance-defined and contrast-defined letters in observers with amblyopia.
abstract: We assessed whether or not the sensitivity for identifying luminance-defined and contrast-defined letters improved with training in a group of amblyopic observers who have passed the critical period of development. In Experiment 1, we tracked the contrast threshold for identifying luminance-defined letters with training in a group of 11 amblyopic observers. Following training, six observers showed a reduction in thresholds, averaging 20%, for identifying luminance-defined letters. This improvement transferred extremely well to the untrained task of identifying contrast-defined letters (average improvement=38%) but did not transfer to an acuity measurement. Seven of the 11 observers were subsequently trained on identifying contrast-defined letters in Experiment 2. Following training, five of these seven observers demonstrated a further improvement, averaging 17%, for identifying contrast-defined letters. This improvement did not transfer to the untrained task of identifying luminance-defined letters. Our findings are consistent with predictions based on the locus of learning for first- and second-order stimuli according to the filter-rectifier-filter model for second-order visual processing.
authors.affiliation: School of Optometry, University of California, 360 Minor Hall, Berkeley, CA 94720-2020, USA. s.chung@berkeley.edu
authors.forename: Susana T L
authors.initials: ST
authors.lastname: Chung
authors.forename: Roger W
authors.initials: RW
authors.lastname: Li
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Levi
mesh_terms: D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000503:physiopathology / Q000523:psychology*; D015350:Contrast Sensitivity; D005260:Female; D006801:Humans; D007858:Learning; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012684:Sensory Thresholds; D014163:Transfer, Psychology; D014792:Visual Acuity; D055815:Young Adult