Local Precedence with Intact Global-Level Processing and Superior Simple Auditory Stimuli Processing Abilities in Adolescents with Autism

Background: Previous studies (e.g. Mottron et al., 2000; Foxon et al., 2003) found local processing superority by employing absolute sound, chord and musical rhythm, but whether global processing is intact in persons with autism is still in debate.

Objectives: we used a hierarchical auditory stimuli to investigate the effects of interference and contigence in auditory stimulus sequence processing in persons with autism and their perceptual processing ability to simple auditory stimuli.

Methods: twenty-seven adolescents with autism (mean age = 12;8 years) and twenty-seven non-autistic adolescents participated in the study. The participants were matched on Chinese norms of Raven’s Standard Progressive Matrices RSPM score, CA, gender and manual laterality. Materials were auditory stimulus sequence composed of three sine swept waves created by a software program. The participants were asked to detect if the stimuli were rising, press ‘rising’ key, and if they were falling, press ‘falling’ key. a) global level processing judgement; b) local level processing judgment, c) simple auditory stimuli judgement.

Results: In global processing task, no significant difference between the two groups was found in global processing, but local-to-global interference effect existed in autistic group. In local processing task, local precedence was found in autistic group, and global-to-local interference effect in both groups. In simple stimuli task, participants with autism showed better perceptual performance than the comparison group.

Conclusions: Adolescents with autism showed intact global processing and local precedence, and superior simple auditory stimuli perceptual ability in auditory processing. These results support the Enhanced Perceptual Functioning hypothesis in autism, which proposes an enhanced low-level processing ability, together with intact processing of static global information.