VISUAL SENSORY PROCESSING IN AUTISM

Individuals with Autism Spectrum Disorder often have an inability to attend to, learn and process sensory stimuli. This also includes the visual sense.

The general visual symptoms shown by individuals with Autism Spectrum Disorder are

  • Gaze aversion
  • Looking through the corner of the eyes
  • Prolonged fixatory gaze on light patterns, windows etc.
  • Showing attraction for shiny surfaces, mirrors etc.
  • Excessive fixation on one object and ignoring other objects in the room
  • Avoids/prefer a particular colour
  • Avoidance or anxiety of fast moving objects or beings
  • Prefer spinning objects. Holds them close to the face
  • Lack of interest in one’s surrounding
  • Excessive lining up of toys or objects
  • Flicking or fidgeting fingers near the face
  • Walks on toes
  • Vacant staring

The visual sense could be hypo or hyper sensitive. And treatment should always include the child’s specific strengths and challenges: including the auditory processing, language utilisation, visuo-spatial processing, motor planning, etc.

What research says on the same

Those with Autism Spectrum Disorders show atypical visual behaviours that can be interpreted as avoiding input (if they cover their eyes in presence of bright lights) or seek more visual stimulation (twisting fingers before their eyes). These are very similar to the tactile and auditory domains.

One of the heavily studied topics under visual perception in autism is that of face processing given its important relation with human social interaction. fMRI studies using eye-tracking show us that the excitation of the fusiform and amygdela is reduced in those with Autism Spectrum Disorder but has improved excitation with increased amount of fixation time on the eye region of the face. EEG studies on ɣ band activity that represents the visual information binding shows concurrent evidence for a neurophysiological difference in face processing in those with Autism Spectrum. Also, the type of visual information matters; those with Autism respond more actively to neutral and detailed, high-spatial frequency and less actively to rapid low-frequency processing which is abundant in our fast-paced social world. From recent studies, the emotional disposition of face processing suggests a hyperactivity in the right Amygdala with adjusted connectivity between  the frontal and temporal lobes. This could be a result from either reduced visual exploration in infancy or could be a secondary to social cognitive deficit.

Deficits in processing simple stimuli and faces also extends to studies on biological movement, children with Autism show impairments in processing dynamic noise, organising movements, and shape from movement detection. Studies suggest this observed deficit maybe due to an atypical processing of  emotional information as compared to typical children. This finding shows a potential disconnect from the limbic or “emotion” neural networks which convey information to sensory processing regions. To talk from a genetic perspective, these differences in processing movement have also been found in the siblings of those with Autism Spectrum Disorder. Thus in accordance with theories suggesting increased local cortical activity with impaired long range connectivity,  children with Autism Spectrum seem to be over using their left primary cortex for movement organisation as observed from fMRI studies. Put together, these studies further suggest a disruption in the processing of basic single mode sensory information which is the basis of higher order cortical abilities such as socialization