Many children with autism experience unusual responses to sensory stimuli, or input.17 These responses are due to difficulty in processing and integrating sensory information. Vision, hearing, touch, smell, taste, the sense of movement ( vestibular system) and the sense of position ( proprioception) can all be affected. This means that while information is sensed normally, it may be perceived much differently. Sometimes stimuli that seem "normal" to others can be experienced as painful, unpleasant or confusing by the child with Sensory Integration Dysfunction (SID), the clinical term for this characteristic. (SID may also be called Sensory Processing Disorder or Sensory Integration Disorder.)
SIDs can involve hypersensitivity, also known as sensory defensiveness, or hyposensitivity. An example of hypersensitivity would be the inability to tolerate wearing clothing, being touched, or being in a room with normal lighting. Hyposensitivity might be apparent in a child's increased tolerance of pain or a constant need for sensory stimulation.