Examining the Effect of Attention on Sensory Registration in Autism Spectrum Disorders

Background: Individuals with autism spectrum disorders (ASD) have significant deficits in sensory processing and attention. Researchers have suggested that sensory processing deficits in ASD may be associated with deficits in attention. However, there is a lack of research systematically examining the impact of attention on sensory processing at the neural level.

Objectives: The study examined the effect of attention on phases of neural auditory processing in individuals with autism spectrum disorders (ASD) using electroencephalography (EEG). We hypothesized that consciously directing attention to incoming information would result in more typical neural processing in individuals with ASD.

Methods: Participants included 24 young adults with high-functioning ASD (17 – 30 years; M = 23.31, SD = 3.77; 17 males) and 24 age-matched neurotypical individuals. All participants were administered a performance-based measure of attention, the Test of Everyday Attention, and filled out the self-report Adolescent/Adult Sensory Profile. Individuals with ASD had significantly greater attention deficits and sensory processing challenges compared to the neurotypical group. EEG data were recorded while they heard random presentations of four auditory stimuli (50 milliseconds in duration) at two different frequencies (1 and 3 kHz) and at two different intensities (50 and 70 dB). All participants completed two attention conditions; the passive condition involved only listening to the stimuli, followed by the active condition, wherein participants were instructed to press a button only to the 1 kHz 50 dB tone. For each condition, participants heard 80 trials of each tone in pseudo-random order with a two-second inter-stimulus interval. Repeated-measures ANOVAs were used to examine the N1-P2-N2-P3 amplitude and latency differences. Additionally, time-frequency analyses were used to examine neural oscillatory activity.

Results: Directing attention to the tones resulted in P2, N2, and P3 amplitude and latency differences for all participants. There were no group differences in N1, P2, N2, or P3 amplitudes for either attention condition. However, individuals with ASD had significantly longer N1, N2, and P3 latencies, suggesting delayed processing. N1 latency delays were present during both attention conditions. N2 and P3 latency delays were present during the passive condition but not during the active condition, implying an attention-based amelioration of the processing delay in ASD. Behavioral measures of sensory processing and attention correlated with neural measures of auditory processing, such that more efficient neural processing (shorter N1 latency) was associated with more typical attention and sensory processing abilities.

Conclusions: Actively directing attention to the tones impacts auditory processing, and may result in more typical processing in ASD. Study findings have significant implications related to understanding neural auditory processing in ASD and provide support that sensory processing issues in ASD are related to attention. Additionally, these results can help practitioners understand the neural basis of behavioral manifestations of ASD, especially those atypical behaviors that occur in response to sensory experiences in everyday activities.