What is Sensory Integration?

Ayres Sensory Integration ®

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In 1989 Jean Ayres defined Sensory Integration (SI) as follows:

“Sensory Integration is the neurological process that organises sensation from one’s own body and from the environment and makes it possible to use the body effectively within the environment.  The spatial and temporal aspects of inputs from different sensory modalities are interpreted, associated and unified.  Sensory integration is information processing… The brain must select, enhance, inhibit, compare and associate the sensory information in a flexible, constantly changing pattern, in other words the brain must integrate it.”

SI theory is intended to explain mild to moderate difficulties in learning and behaviour.

More specifically, those difficulties related to motor incoordination and poor sensory processing that cannot be attributed to obvious central nervous system (CNS) damage or abnormalities. Of note are the praxis disorders, i.e. bilateral integration and sequencing dysfunction and somatodyspraxia.  “Dyspraxia is defined as difficulty in planning and carrying out skilled, non-habitual acts in the correct sequence…Praxis is knowing what to do and how to do it and doing it.” Ayres 1972.

Sensory integrative disorders also include postural movement disorders, postural – ocular movement disorders and sensory modulation disorders.


An occupational therapist trained in Ayres Sensory Integration ® accredited by SAISI would be able to make a diagnosis of a SI dysfunction.

To make a diagnosis of SI dysfunction, there needs to be evidence of a deficit in processing of vestibular,
proprioceptive or tactile sensory inputs.  These deficits must not be a result of either peripheral or central nervous system dysfunction.

The use of various standardised and non-standardised assessments, checklists and clinical observations are used in collaboration with collateral information.  Currently, “The Sensory Integration and Praxis Test (SIPT)” is the golden standard for testing internationally.  As occupational therapists it is important that all information obtained during testing is confirmed with evidence obtained from the child’s functional abilities at home and at school.

What could a SI dysfunction include?

Difficulties experienced in Sensory Integration dysfunction may include:
• Clumsy behaviour; child may trip / fall often, bump into things etc…
• Postural control may be poor.
• Sensory defensiveness, i.e. fussy dressers (only cotton, seams turned out), fussy feeders, uneasy on jungle gyms/avoid swings, unsettled in noisy environments (e.g. parties/ shopping malls), etc.
• Sensory dormancy (often resulting in seeking behaviours), i.e. constantly moving, fidgeting, touching, making noises, crashing into things, not hearing when being called (despite normal hearing), incomplete work in class due to “daydreaming”, etc.
• Difficulties co-ordinating the two sides of the body and/or crossing the body midline, as seen when swimming, riding a bicycle, eating with a knife and fork.
• Difficulties planning, sequencing and executing novel (new) movement patterns. Takes longer than average to learn new tasks such as riding a bicycle.
• Speech and language development may be affected.
• Poor self-care.
• Difficulties developing and sustaining relationships and poor social skills.
• Difficulty with focus and attention.

Difficulties in SI dysfunction are classified in two areas:
1. SI dysfunction of modulation
2. SI dysfunction of discrimination

It is important to always keep differential diagnoses in mind, i.e. emotional issues, Attention Deficit /Hyperactivity Disorders, Hemispheric dysfunction, Autistic Spectrum Disorder, Cerebral Palsy, Down’s Syndrome, hearing and visual impairments.

What is Sensory Modulation?

Sensory modulation refers to the ability of the nervous system to regulate, organize and prioritize incoming sensory information, inhibiting or suppressing irrelevant information and prioritizing and helping the child to focus on relevant information.

A child with a well-modulated nervous system adapts effectively to changes in the environment and is able to maintain a level of arousal and attention appropriate to the task at hand.  The child is able to block out irrelevant information, attend to relevant information and respond appropriately and adaptively. This enables the child to engage in a meaningful manner in activities of daily life.

E.g. in the classroom environment, a child is able to ignore the background noise of children talking, feet scuffling the floor, bells ringing, enabling him/her to attend to the teacher’s voice to listen to the instructions and execute the task required.

What is Sensory Discrimination?

Sensory discrimination is the interpretation of sensory input within the central nervous system to make sense of what is perceived, forming perceptions and allowing for response to sensory input. E.g. hearing a noise (registering), interpreting it is your name being called, resulting in responding by either turning your head towards the stimulus or verbally answering to the call.


Evaluation in SI is an on-going process. Continued discussion with caregivers, teachers etc. is vital.

A combination of the following is used to gather data:
• Interviews with parents, caregivers, teachers etc.
• Sensory history questionnaires, standardized questionnaires, i.e. The Sensory Profile by W. Dunn, The Touch Inventory for Pre-schoolers (TIP), Sensory Processing Measure Home (by Parham and Ecker), Sensory Processing Measure School (by Kuhaneck, Henry and Glennon) as well as non-standardized questionnaires, i.e. checklist for tactile defensive behaviour, sensory motor history.
• Observations in natural settings, i.e. home / school / playground.
• Clinical observations and formal observations during standardized testing.
• Formal assessment / Standardized testing, i.e. The Sensory Integration and Praxis Tests (SIPT), Millers Assessment for Pre-schoolers (MAP), the Test of Sensory Function in Infants (TSFI) and DeGangi-Berk Test of Sensory Integration.
• Continued observation during therapy and continued interaction with parents is of the utmost importance.


“The central principle in sensory integration therapy is providing planned and controlled sensory input with the objective of eliciting a related adaptive response in order to enhance the organisation of brain mechanisms” (Ayres 1972).  An adaptive response is defined as a purposeful, goal directed behaviour which suggests that the child can master the demands of the environment. Adaptive behaviour promotes sensory integration, but is also dependent on sensory integration.  Observation of adaptive responses also provides an indication of the degree of sensory integration that is taking place during an activity. It is the role of the therapist to adjust activities so as to provide “the just right challenge” for the child. Ayres (1972) believed that the young brain is naturally malleable and by providing and controlling the sensory input the brain is capable of change. Thus it is assumed that enhanced nervous system function is possible through the provision of controlled tactile, vestibular and proprioceptive sensory inputs (in Fisher, Murray & Bundy, 1991).

It is believed that sensory integration in a typically developing child occurs in a developmental sequence.   SI theory hypothesizes that by systematically providing therapeutic sensory motor experiences, aimed at facilitating typical neuro-motor development, we can enhance brain function and thus enable more typical developmental sequences. This rationale is based in the concept of neuroplasticity, the capacity of the nervous system to adapt in response to the provision of enhanced sensory inputs (Bundy and Murray 2002).  Jacobs and Schneider (2001) in Curtis and Decell Newman (2004) stated that enriched sensory experiences may facilitate the formation and development of neural connections. Sensory integration is believed to encourage neural plasticity when a child actively engages in enriched sensory-motor experiences.

When a child responds to his environment in an adaptive and creative way, he is able to learn and have fun.  This ‘fun’ and ability to learn, relies on intact sensory integration.  Occupational therapists use purposeful activities, specialized equipment and sound clinical reasoning to create opportunities for enhanced sensory integration in therapy. Once the child is processing and organising sensory information more effectively, he will find it easier to interact positively with his peers, play creatively and achieve success in all of his occupational performance areas at home and at school.