Objectives: To test the possibility that cognitive differences in visual discrimination and attention to detail may actually involve atypical low-level visual thresholds.
Methods: 15 adult males diagnosed with High-Functioning autism (HFA) & Asperger Syndrome (AS) and 15 control adult males took part in the study. Participants were administered the Freiberg Visual Acuity and Contrast test (FrACT), a standardised optometric test.
Results: The ASC group scored a mean visual acuity measure (20:7) that was significantly better than the control group (20:13) by a factor of two. To put this in perspective, birds of prey have visual acuity approximately two and a half times better than humans.
Conclusions: The results provide a possible explanation for enhanced perceptual functioning and attention to detail seen in ASC; indicating that remarkable visual acuity may be an underlying factor. The results of this study also suggest that inclusion of measures of sensory hypersensitivity as diagnostic criteria is justified and that basic standardised tests of sensory thresholds may inform causal theories of ASC. Since ASC are genetic in origin, this points to genes involved in sensory neurophysiology playing a key role.