Sensory Integration Dysfunctions in Autistic Children
According to Ayers (1991), the typical symptoms of dysfunctions of sensory integration processes in autistic children are similar to disorders observed in dyspraxic children (that is children having problems with motor planning). They have difficulties with locating the sensorial stimulus, planning movement and imitating movement.
Problems concerning improper sensory processes in autistic children are as follows:
Dysfunction of input stimulus registration
Autistic children usually do not notice hearing and vestibular stimuli. They neglect some sounds, while other sounds cause excessively strong responses. They avoid visual sensations, engage in very limited eye contact, look through people, focus their sight on details and lines, and rather frequently use peripheral vision. They often have problems with the registration of taste and smell sensations. Children may not respond even to strong smells, but more often they are hypersensitive to smell. Sometimes they look for intensive smells and tastes. Autistic children are typically characterised by no response to pain stimuli when they display auto-aggressive behaviours, such as biting, pinching or banging their head with various objects.
Input data modulation disorder
This refers mostly to vestibular and tactile stimuli. It manifests itself through gravitational insecurity and hypersensitivity to touch. The nervous system cannot launch adequate processes of information stimulation and obstruction so that the motor response would be adapted to the force and kind of stimulus. Every change disturbs the sense of safety. The child feels that they lose control over external stimuli reaching them from without. Since they have difficulties with the reception and modulation of hearing stimuli, the speech perception is hindered.
Disturbed triggering of motivational processes
In autistic children, the parts of brain responsible for triggering action do not work properly. This refers to the registration of stimuli which, in consequence, disturbs the formation of the full concept of an object and the assessment of potential possibilities of using many things. The brain’s operation related to the triggering of motivation for action depends on the mechanisms of registering stimuli and attention to the information coming from the environment. Autistic children often have weaker motivational mechanisms, which causes that simple activities do not develop into more complex forms of behaviour. A child focuses on simple repetitive actions, because more complicated tasks are, at the same time, more difficult to control. Control is understood here as the possibility of imagining the meaning of objects and the consequences of events. This particularly refers to new experiences.
Incorrect processing of sensory data causes that autistic children:
- Have difficulties with fast creation of visual representation of the object,
- Do not properly develop the body scheme,
- Have problems with imagining potential possibilities of using an object,
- Are unwilling to engage in purposeful activities,
- Refuse to perform new activities and do not feel pleasure in situations that differ from the ones they knew earlier,
- Display limited cognitive curiosity, natural exploration of the surroundings and willingness to experiment, which consequently weakens their interactions with the environment.