Basic Auditory Processing Difficulty in the Youth with Autistic Feature

Background:  The population with ASD is hypersensitive to simple stimuli.  This atypical perceptual processing is observed in both visual (Bertone, 2005) and auditory modalities (Lepisto, 2008).  One explanation for this hypersensitivity is internal noise in neurons.  According to this hypothesis, the complexity of stimuli influences the ability to perceive/discriminate basic perceptual properties.  However, it is difficult to assess the ‘internal noise’ at the behavioral level.  In addition, it is still unclear how this internal noise is related to ASD people’s social skills.

Objectives: The present study was designed 1)to assess ‘internal noise' in young adults with Autistic feature using the modified auditory Go-NoGo task (Song & Kwon, 2015), and 2)to examine whether basic auditory processing predicts the severity of Autistic feature, even after controlling for IQ and visual processing.

Methods: Participants were 102 undergraduate students (Mean Age =21.43; 40 males and 62 females). IQ(M = 12.49 for Block design, M=11.94 for Vocabulary),  EQ (Baron-Cohen & Wheelright, 2004; Her & Lee, 2011), and AQ (Baron & Cohen, 2001) were assessed. Based on their performance on the AQ test, we divided the subjects into two groups: high AQ group (the top 30% (AQ>22)) and low AQ group (the bottom 30% (AQ <14)). None of  gender, age and IQ differed across the two groups. The visual processing was assessed by using Bertone et al’s (2005) Orientation Identification Task, and the auditory processing was assessed by using the modified auditory Go-No Go task (Song & Kwon, 2015). The modified auditory Go-No Go task required the ability to inhibit their dominant response (e.g. pressing an arrow key) when a softer sound was presented right after the first sound was presented. Their performance level was evaluated by assessing individual thresholds to reach 70% accuracy.  A low threshold meant a high sensitivity. A half of the trials contained simple tones and the other half contained complex tones.

Results: We conducted hierarchical multiple regression analyses to analyze the relationships among IQ, the visual processing and the auditory processing. There were interesting group differences between the high AQ group and the low AQ group. In the high AQ group,  their IQ score was positively associated with the visual processing (r=.545, p<.05) and their performance on the Go-NoGo test in both pure tone and complex tone conditions predicted their EQ (social function) scores respectively (t=-.2.235, p<.05 for pure tone; t=-2.103, p<.05 for complex tone), even after controlling for IQ and the visual processing. In contrast, none of significant relationships for the same tests was observed from the low AQ group.  

Conclusions: Basic auditory processing is a significant predictor of the social function in the youth with ASD feature, even after controlling for IQ and visual processing. In addition, the Go-Nogo task was proved to indirectly represent the internal noise-related function. ASD people's difficulty in inhibiting a response to a softer volume could be a valuable variable in developing a method for the early detection and intervention.