Bonneh YS., Popple A., Howitt DH., Adini Y.
Background: Many children with autism often cover their ears or look to the side spontaneously without any apparent cause. Here we report the case of DH, a high functioning adult with ASD who may shed some light on this enigmatic behavior. DH reports frequent periods of “overwhelming perception” in which external stimuli “consume his attention” in an adverse and stressful way, while experiencing a restricted sense of space, perceiving parts of space and modalities (vision, audition, touch) one at a time. DH was uninformed about the details of the study during the testing, and is credited for his important insights.
Methods: DH monitored simple auditory (6 Hz soft 500 Hz beeps), visual (dynamic and static patterns, e.g. 2 deg. flickering bright disk) and crossmodal stimuli (combinations of the above) for 1 minute periods and reported intermittent states of “hyper perception” by depressing two buttons. In some tests, 128-channel EEG data were recorded.
Results: DH reported “hyper perception” for over 50% of the time in episodes of 1-10s for each modality in isolation and alternating hyper states of vision (~25%) and audition (~35%) when presented simultaneously. Hyper audition was more frequent in the left ear and could be reduced with specific sound patterns. Hyper vision was reported as disappearance of part of the stimuli with the remainder consuming all space. Preliminary EEG analysis showed that the amount of “hyper perception” across conditions correlated with the magnitude of high beta oscillations (20 Hz) in the occipital and parietal lobes of the right hemisphere.
Conclusion: The case of DH suggests that the enigmatic autistic behavior of covering the ears or looking to the side is due to abnormally focused attention that discards stimuli outside its focus and results in an adverse and stressful perception. Avoiding strong exogenous stimuli or detaching in various ways may reduce these effects, but could be a cause for abnormal development.