Altered auditory and multisensory temporal processing in autism spectrum disorders

Abstract

Autism spectrum disorders (ASD) are characterized by deficits in social reciprocity and communication, as well as by repetitive behaviors and restricted interests. Unusual responses to sensory input and disruptions in the processing of both unisensory and multisensory stimuli also have been reported frequently. However, the specific aspects of sensory processing that are disrupted in ASD have yet to be fully elucidated. Recent published work has shown that children with ASD can integrate low-level audiovisual stimuli, but do so over an extended range of time when compared with typically developing (TD) children. However, the possible contributions of altered unisensory temporal processes to the demonstrated changes in multisensory function are yet unknown. In the current study, unisensory temporal acuity was measured by determining individual thresholds on visual and auditory temporal order judgment (TOJ) tasks, and multisensory temporal function was assessed through a cross-modal version of the TOJ task. Whereas no differences in thresholds for the visual TOJ task were seen between children with ASD and TD, thresholds were higher in ASD on the auditory TOJ task, providing preliminary evidence for impairment in auditory temporal processing. On the multisensory TOJ task, children with ASD showed performance improvements over a wider range of temporal intervals than TD children, reinforcing prior work showing an extended temporal window of multisensory integration in ASD. These findings contribute to a better understanding of basic sensory processing differences, which may be critical for understanding more complex social and cognitive deficits in ASD, and ultimately may contribute to more effective diagnostic and interventional strategies.

Keywords: audiovisual; autism; cross-modal integration; multisensory; sensory processing; temporal binding.

Figures

Figure 1

Task design. (A) Visual TOJ task. (B) Auditory TOJ task. (C) Multisensory TOJ task. In multisensory conditions, two circles are presented sequentially above and below the central fixation point. One beep is always presented simultaneously with the first circle, whereas the second beep is presented with a varied delay (0–500 ms) from the onset of the second circle. See text for additional detail.

Figure 2

Threshold values for visual and auditory temporal order judgment tasks. Children with autism spectrum disorders (ASD) show similar thresholds to typically developing children for the visual TOJ task (A). However, children with ASD show significantly larger thresholds for the auditory TOJ task (B). (*p < 0.05). Note that each of these threshold values was confirmed via a validation procedure (see text for additional detail). Error bars represent standard error of the mean (SEM).

Figure 3

Performance accuracy (A) and response time (B) for simultaneous multisensory trials (i. e., multisensory delay = 0) compared to visual-only trials. Error bars represent standard error of the mean (SEM).

Figure 4

Percent improvement in accuracy relative to visual-only performance as a function of multisensory delay. Whereas typically developing children show improvements for short delays (i.e., 50–150 ms), children with ASD show improvements for both moderate and short delays (i.e., 0–300 ms). The solid line indicates continuous significant (p < 0.05) differences from zero (i.e., the multisensory temporal window). Error bars represent standard error of the mean (SEM).

Figure 5

Improvement in response times relative to visual-only performance as a function of multisensory delay. Whereas typically developing children show improvements for short delays (i.e., 0–200 ms), children with ASD show improvements for both moderate and short delays (i.e., 0–300 ms). The solid line indicates continuous significant (p < 0.05) differences from zero. Error bars represent standard error of the mean (SEM).