In contrast to previous reports, for those with autism or Asperger's syndrome, recognizing facial expressions is separate from identifying familiar faces, according to a study published in Neurology, the scientific journal of the American Academy of Neurology.
Those who had an impaired ability to process facial identity were no different than those with normal facial identity ability, when it came to processing facial expression.
Led by researchers in the U.S. and Canada, the study examined 26 adults diagnosed with either autism, Asperger's syndrome, social-emotional processing disorder, or both Asperger's and social-emotional processing disorder. The shared trait of these disorders is social dysfunction. The individuals took a variety of tests to measure famous face recognition, recognition of non-facial emotional cues (from voices or bodies), recognition of basic emotions (happy, sad, angry, fearful), and recognition of a complex mental state (reflective, aghast, irritated, impatient) presented by a pair of eyes.
Ten of the participants scored well within the normal range for famous face recognition, and the other 16 scored at an impaired level.
For recognizing facial expression, these two groups showed a surprisingly similar range of performance and variability. Out of a possible score of 80 points, the 10 with normal identity recognition scored an average of 62.3, and the 16 with impaired identity recognition scored an average of 59.8. Scores were also similar for recognizing non-facial expression. Out of a possible score of 84 points, the first group scored an average 59.5 and the second group scored an average 56.9.
"One might have thought that there would be a high correlation between identifying faces and understanding facial expressions, but that wasn't the case. Instead there was a correlation between facial and non-facial expression analysis," said study author Jason J. S. Barton, MD, PhD, FRCPC, a professor of neurology and ophthalmology at University of British Columbia in Vancouver. "These results suggest that problems with judging facial expressions in these patients may be related more to the processing of emotion than to the perception of faces."
Future study would include functional imaging of these individuals while they perform the identity and expression recognition tasks, Barton said.
The study received funding support from a grant by the National Institute of Mental Health, a Canada Research Chair, and a Michael Smith Foundation for Health Research Senior Scholarship.
Earlier this year Barton was awarded the Norman Geschwind Prize for Behavioral Neurology from the American Academy of Neurology.