People often use the terms ‘Sensory Integration’ (SI) and ‘Sensory Processing’ to refer to the same theory. A. Jean Ayres first published the theory in 1972. She was the first author to use the term ‘Sensory Integration’ to describe sensory issues in children. Following this the term ‘Sensory Processing Disorder‘ (SPD) was used in 2006, by Lucy Miller. Miller’s model is certainly based on Ayres’ original theory.
Nowadays, authors typically use either one term or the other, depending on their training and/or work experience. Therapists will usually use the term that they were taught when they trained. This is influenced by who they trained with, and where and when they completed their training.
To clarify ‘Sensory Integration’ and ‘Sensory Processing’ refer to the same initial idea of how the brain processes sensory messages. The differences between SI and SPD are subtle. In order to explain them, this post gives a short history of Ayres’ and Miller’s work.
A. Jeans Ayres in 1972 (p.1) first described Sensory Integration (SI) as ‘the organisation of the senses for use.’ Ayres was a psychologist and occupational therapist working with children with learning disabilities in California. Noticing that many of these children interpreted sensory messages differently to their peers, she began to focus her attention on the touch, vestibular, proprioceptive and vision senses. Her research indicated that the children she was working with did not integrate, or combine, the messages from these senses very well. This is why she used the term sensory integration.
As a result of poor sensory integration, she theorised children could challenges with their
- Coordination of both sides of the body (bilateral integration),
- Sensory sensitivity,
- Poor discrimination and/or,
SI and learning
Ayres felt that these sensory integration challenges were contributing to the children’s difficulties with learning. This can be seen in her original model shown in the picture below. On the left, the model shows the senses Ayres felt were most likely to contribute to SI challenges. As you follow the model to the right, it shows the skills that each sense influences. Ayres felt that each skill built on the next, resulting in the end products of concentration, attention, learning etc.
Through her work, Ayres found that if she treated the children using a SI approach they made improvements in their learning. The approach is called a ‘bottom up’ because it works on improving foundation abilities with the expectation that this will have a knock on effect to function skills. So, for example, Ayres felt if she worked on postural control and discrimination that a child’s handwriting would improve without working specifically on handwriting. Many therapists still use this treatment approach today (Ayres® SI).
Image: Western Psychological Services SI and the Child 1979
Sensory Processing Disorder
Lucy Miller first used the term Sensory Processing Disorder (SPD) in 2006 to describe sensory issues in her book, Sensational Kids. Miller had initially studied under Jean Ayres. After this she has continued to research SI along with her colleagues. The primary aim of this research was to have SPD identified as a stand-alone diagnosis by the American Psychology Association in their updated manual the DSM-5. Miller defined three parts to SPD: modulation; discrimination and sensory-based motor disorders.
Miller’s model draws heavily on Ayres’ initial work and theory. In my opinion, however, Miller’s format is easier for parents and teachers to follow.
Miller also published her treatment model in 2012 (A SECRET, Bialer & Miller).
Image: Lucy Miller, Sensational Kids; Hope and Help for Children with Sensory Processing Disorder (2006)
Overall, what is the main difference between SI and SPD? At their core, both models refer to the same primary idea, they just 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 calls ‘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.
Is there a difference in how therapists from each tradition (SI or SPD) approach treatment?
In short, yes.
A pure Ayres SI® approach will be led by a trained therapist in a specialised clinic space. It must be child-led. The therapist continually creates opportunities at a ‘just right’ level to help improve the child’s sensory integration. Therapists using Ayres® SI should use the fidelity guidelines outlined by Parham and colleagues in 2011. These guidelines describe the core components of the Ayres® SI treatment.
Miller’s model uses elements of 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.
Sensory Integration vs Sensory Processing Disorder
In summary, the terms ‘sensory integration’ and ‘sensory processing’ refer to the same theory and idea. As with many ideas, once the founder has passed on their knowledge, different roads are taken by their students. This has been the case for SI theory, resulting in the term ‘sensory processing’. My hope is that these different roads will ultimately lead to stronger evidence, and the best outcomes for children and adults that need help to organise their senses.
A History of Sensory Integration vs Sensory Processing Disorder
Jean Ayres begins working on her theory of SI.
Jean Ayres publishes Sensory Integration and Learning Disorders. In this book she outlines her SI theory and discusses how children can be assessed for SI dysfunction. The book also includes recommendations on how to treat and support children who have sensory challenges.
Sensory Integration and the Child is published. Jean Ayres wrote this book for parents in order to break her SI theory into a more easily read format. Publishers released an updated 25th anniversary edition of this book in 2004. The newer edition includes comments from occupational therapists currently researching SI.
Some authors, especially in education, discredit the effectiveness of SI for children. All readers must, however, note that a huge flaw with many of studies at this time is that they do not quantify what classes as ‘sensory integration.’ Many studies call sensory strategies such as weighted blankets and ball chairs ‘SI treatment,’ even though they are not. This is like calling an ace of spades and king of diamonds, although the two may be cards, they are not the same.
Winnie Dunn publishes the ‘Sensory Profile.’ This is the first standardised assessment available to look at sensory modulation difficulties. You can read more about sensory modulation on our ‘What is SPD?’ page. Dunn published an updated version of the tool in 2014 (SP2).
Above all there is a huge push for all research on SI theory and treatment to be of high quality. In order to do this, researchers must describe exactly what their treatment process involved.
Lucy Miller and colleagues formally publish the term Sensory Processing Disorder (SPD) in their books. Parnham and colleagues also publish a fidelity measure, this clearly describes the components of SI treatment. They, therefore, recommend this is used in all research on SI effectiveness.
The term Sensory Processing Disorder is used more widely in media, publications, especially books on the topic for parents and teachers. However, many books written for therapists typically continue to use the term SI. Schaff and Davies (2010) discuss the evolution of SI in an editorial for the American Journal of Occupational Therapists. Overall, they conclude there is no consensus on term use and advocate continued research.
Authors continue to use the terms SI and SPD interchangeably. A huge amount of research is currently being done to support the use of SI treatment, including using SI for children with autism. This also includes randomised control trials, the most rigorous type of evidence. For more information on publications, you can follow the links at the end of this timeline.
The Ayres 2020 vision team are working on a new assessment tool the EASI to help therapists assess for sensory integration dysfunction. They aim to have publish this in 2020.
Therapists continue to train in Ayres® SI through organisations including the SI Network, CLASI and the University of Southern California. In addition, Lucy Miller offers training in her A SECRET model, this now includes university certification.
What about current research/evidence on SI and SPD?
These websites often update their publication list:
- Ayres 2020 Vision Goal 1
- Sensory Integration Global Network
- Star Institute Research & Publications
Where can I learn more about Sensory Integration?
SI for parents & teachers & health professionals
For parents, teachers and those new to the sensory world, we have an online introductory course available.
Sensory integration for allied health therapists
These organisations provide training for therapists:
- CLASI (Global)
- SI Network (UK & Ireland) – offer a lot of online options
- Pediatric Therapy Network (California USA)
- STAR Institute (Denver USA)
Books & page references
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.*
- Bialer D., Miller. L.J. (2012). No Longer A Secret: Unique Common Sense Strategies for Children with Sensory or Motor Challenges.
- 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.
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