Measuring the effects of alexithymia on perception of emotional vocalizations in autistic spectrum disorder and typical development

Background
The results from recent studies suggest that alexithymia, a disorder characterized by impairments in understanding personal experiences of emotion, is frequently co-morbid with autism spectrum disorder (ASD). However, the extent that alexithymia is associated with primary deficits in recognizing external emotional cues, characteristic in ASD, has yet to be determined.

Method
Twenty high-functioning adults with ASD and 20 age- and intelligence-matched typical controls categorized vocal and verbal expressions of emotion and completed an alexithymia assessment.

Results
Emotion recognition scores in the ASD group were significantly poorer than in the control group and performance was influenced by the severity of alexithymia and the psycho-acoustic complexity of the presented stimuli. For controls, the effect of complexity was significantly smaller than for the ASD group, although the association between total emotion recognition scores and alexithymia was still strong.

Conclusions
Higher levels of alexithymia in the ASD group accounted for some, but not all, of the group difference in emotion recognition ability. However, alexithymia was insufficient to explain the different sensitivities of the two groups to the effects of psycho-acoustic complexity on performance. The results showing strong associations between emotion recognition and alexithymia scores in controls suggest a potential explanation for variability in emotion recognition in non-clinical populations.