Visual and auditory sensitivity in autism spectrum disorders
Individuals with an autism spectrum disorder (ASD) often cannot tolerate certain sights and sounds, such as fluorescent lights, vacuum cleaners, and babies crying, which affects their ability to engage in activities at home and in the community. One theory that may account for these sensory impairments is the Enhanced Perceptual Functioning theory, which posits that individuals with ASD are more sensitive to auditory and visual stimuli. Previous studies in support of this theory found that individuals with ASD demonstrated an enhanced ability to detect differences in pitch, discriminate changes in visual stimuli, and detect novel targets in visual arrays. The response type and task demands differed greatly among these studies, making it difficult to draw firm conclusions. Furthermore, no studies have compared visual and auditory perception directly. The current study sought to fill these gaps by examining visual and auditory perception in a sample of 13 children with ASD and 13 children with typical development aged 8-12 years. It was predicted that individuals with ASD would show increased sensitivity in both auditory and visual domains. To assess perceptual abilities, participants completed an auditory discrimination task examining pitch and volume and a visual discrimination task examining hue and luminance. Using signal detection theory comparing hits and false alarm rates (d-prime) to analyze their performance, children with ASD showed enhanced perception for pitch only compared to children with typical development. In the ASD group, high overall sensitivity were related to an overall measure of autism severity, supporting the notion that enhanced perception, particularly pitch sensitivity, may be a phenotypic marker for ASD. This is the first study to demonstrate a relationship among perceptual sensitivity and ASD symptoms. These results have clinical significance for understanding children with ASD. For example, caregivers and teachers taking children with ASD to a noisy environment such as a gymnasium or the mall may want to provide earplugs or headphones to dampen the noise. It is possible that auditory hyper-sensitivity may underlie the development of difficulties with social-communication and may lead to repetitive behaviors in an effort to manage the environment.