The terms Sensory Integration and Sensory Processing are often used interchangeably to refer to the same theory. The theory was initially identified by A Jean Ayres. Authors will typically use one term and their choice usually depends on their training and work experience. Therapists will often use the term that they were taught when they trained, but this is influenced by who they trained with, and where and when they trained.
Sensory Integration (SI) was first described by A Jeans Ayres in 1972 (p.1) as ‘the organisation of the senses for use.’ Ayres was a psychologist and occupational therapist who was working with children with learning disabilities in California. She had noticed that many of the children she was working with interpreted sensory information differently to their peers. Ayres focussed a lot of her attention on the touch, vestibular, proprioceptive and vision senses. Her research indicated that the children she was working with did not integrate the messages from these senses very well. As a result, she theorised children could have poor posture, poor coordination of both sides of the body, sensory sensitivity, poor discrimination and/or dyspraxia. Ayres felt that the sensory integration dysfunction was contributing to the children’s difficulties with learning. She found that if she treated the children using a SI approach they made improvements in their learning. This treatment approach is still used by therapists today (Ayres SI®).
Image: Western Psychological Services SI and the Child 1979
Sensory Processing Disorder
The term Sensory Processing Disorder (SPD) was first used by Lucy Miller in 2006 in her book Sensational Kids. Miller had initially studied under Jean Ayres. She has since continued to research sensory integration along with colleagues. The primary aim of the collaborative research was to have Sensory Processing Disorder identified as a stand-alone diagnosis by the American Psychology Association in their updated manual the DSM-5. Lucy Miller defined three parts to Sensory Processing Disorder, modulation, discrimination and sensory-based motor disorders. This model drew heavily on Ayres’s initial work and theory. I feel that the format is easier for parents and teachers to follow. Miller has also published her treatment model (A SECRET Bialer & Miller 2011).
Image: Lucy Miller Sensational Kids Hope and Help for Children with Sensory Processing Disorder 2006
At their core, both models refer to the same primary idea but use different terminology. Where Ayres refers to Sensory Integration Dysfunction, Miller and colleagues use Sensory Processing Disorder. Ayres used the term tactile defensiveness to describe what Miller would call sensory modulation, tactile over-responsivity. Ayres described postural ocular and vestibular ocular disorders, but Miller uses the term Sensory Based Movement – Postural Disorders. Both authors use the terms dyspraxia and sensory discrimination. Ayres included bilateral integration and sequencing and Miller has not.
There is, however, a difference in how therapists following the models will approach treatment. A pure Ayres SI® approach will be led by a trained therapist in a specialised clinic space. It must be child-led. The therapist will continually create opportunities at a ‘just right’ level to help improve the child’s sensory integration. Therapists using Ayres SI ® should be following the fidelity measure outlined by Parham and colleagues in 2011. Miller’s model uses this approach; however, it includes additional therapies such as listening therapy. It also includes greater parent involvement in therapy and extra strategies for home and school. Most other authors will outline sensory strategies that can help to support the senses at home and school. These strategies can be used to complement direct sensory integration treatment.
In short the terms sensory integration and sensory processing to refer to the same main theory and idea. For many ideas, once the founder has passed on their knowledge, different roads are taken by their students. This has been the case for sensory integration theory which has led to the use of the term sensory processing. My hope is that these different roads will ultimately lead to strong evidence, outcomes and supports for the children and adults that need help to organise their senses.
A Timeline of SI and SPD
Where can I learn more about Sensory Integration?
For parents, teachers and those new to the sensory world, we have an online introductory course available. There are also extra references below.
For therapists wanting to formally train the following organisations offer programmes:
SI Network UK & Ireland
Where can I find current research/evidence?
The following websites frequently update their publication list:
Star Institute Research & Publications
Asterisks * indicate references that are parent and teacher friendly
Ayres, A.J. (1972). SI and Learning Disorders.
Ayres, J.A. (1979). SI and the Child.*
Dunn, W. (1999). Sensory Profile. User’s Manual. Texas: The Psychological Corporation.
Parham, L. D., Cohn, E. S., Spitzer, S., Koomar, J. A., Miller, L. J., Burke, J. P., et al. (2007). Fidelity in SI practice intervention research. American Journal of Occupational Therapy, 61, 216–227.
Miller, L.J. (2006). Sensational Kids Hope and Help for Children with Sensory Processing Disorder. *
Miller L.J., Anzalone, M.E., Lane, S.J., Cermak, S.A. and Osten, E.T., 2007. Concept Evolution in SI: A Proposed Nosology for Diagnosis. American Journal of Occupational Therapy 61(2), pp. 135-140.
Schaaf, R.C., Davies, P.L., (2010) Evolution of the SI Frame of Reference. American Journal of Occupational Therapy 64 (3), pp. 363-367.