The sensory integration frame of reference was developed by A. Jean Ayres (1972, 1989, 2011), an occupational therapist (OT), with postdoctoral training in educational psychology and neuroscience. The theory of sensory integration was developed to explain behaviors in children with learning problems that were not adequately explained by existing perceptual motor theories.

Ayres (1972, 1989, 2011) combined concepts from neuroscience, psychology, human development, and occupational therapy into a theory of sensory integration that provides a holistic framework for understanding behavior and learning. Although this theory has been updated and expanded, the premise that adequate processing and integration of sensory information provides a building block for skills, such as postural control, bilateral integration, praxis , visual motor skills, and self-esteem.

The theoretical postulates that form the foundation for the sensory integration frame of reference are:

Ayres’s (1989) factor and cluster analyses, and later contributions by colleagues (Davies and Tucker 2010; Mailloux et al. 2011; May-Benson and Cermak 2007; Mulligan 2002), identified patterns of dysfunction in sensory integration which assist in interpretation of assessment data and guide intervention. These patterns include:

Sensory Integration refers to “the neurological process that organizes sensation from one’s own body and from the environment and makes it possible to use the body effectively within the environment” (Ayres 1972, p. 11). Sensory integration includes perception, modulation, and integration of sensory information as a foundation for participation in activities across social, physical, learning, and daily living tasks (Ayres 1972).

Sensory Processing Disorder is a term to identify children with problems processing sensation (Miller et al. 2007). Miller and colleagues propose a taxonomy of sensory processing disorder; however, this terminology is not universally accepted as many therapists prefer to describe children as having difficulty processing and integrating sensation.

Sensory Modulation refers to over or under-responsiveness to typical levels of sensation. In recent years, other terms have been used including hyper- and hypo-responsivity to sensation, sensory over- or under-responsivity, and, most recently, hyper- and hypo-reactivity (American Psychiatric Association 2013). Sensory modulation also refers to the neurological process of assessing sensory inputs for relevance, and adjusting the nervous system’s response to those inputs.

Praxis is the ability to conceive of, organize, and carry out a sequence of unfamiliar, goal-directed actions (Ayres 2011).

Adaptive Response is the ability to respond appropriately and effectively to an environmental, sensory, or task demand (Ayres 1972).

Developmental Coordination Disorder (DCD) is a diagnosis consisting of poor motor coordination in the absence of frank neurological damage which results in deficits in functional performance. Many OTs view dyspraxia as a subtype of DCD and utilize this diagnosis with children with sensory integration-based praxis problems (Cermak and Larkin 2002).

Sensory integration intervention, now referred to as Ayres Sensory Integration® (ASI) intervention, is based on the premise that foundational sensory motor skills are improved through active participation in meaningful individually-tailored sensory and motor experiences, which increase the ability to respond appropriately to, and make adaptive responses to environmental demands, allowing the child to better engage in functional activities. To encourage and promote the ability to demonstrate increasingly more adaptive responses to environmental and task demands, the OT guides and facilitates the selection of therapeutic activities based on the child’s wants and needs. Intervention is often provided in an environment that affords opportunities for participation in active sensorimotor activities that provide levels of sensation that are greater than afforded in usual play environments. This approach often includes the use of specialized equipment, such as suspended swings that can be utilized in multiple ways, that allow for varying levels of linear and rotary movement; that provide opportunities for climbing, rolling, and sitting upon; and that provide opportunities for moving the body in a variety of ways.

ASI is appropriate for any individual who has difficulties processing and integrating sensory information that impacts their ability to participate in chosen activities. This includes children with learning problems, nonverbal learning disability (NVLD), attention deficit disorder, autism spectrum disorder, Tourette’s syndrome, and, in some cases, intellectual disabilities. Individuals with mental health concerns, such as anxiety, depression, obsessive–compulsive disorder, and schizophrenia may also benefit if they demonstrate sensory and/or motor difficulties. It is appropriate for individuals throughout the life span, from infants through adults. ASI is most often associated with children aged 4–8 years.

The etiology of sensory integration problems is not well understood. Recent studies suggest a genetic component with sensory over-responsivity to touch and auditory information (Keuler et al. 2011). May-Benson et al. (2009) found that children with sensory processing problems and children with autism demonstrated high incidences of prenatal maternal stress, assisted delivery, cord wrap, breech position, high birth weight, jaundice, chronic ear infections, and delayed crawling.

Studies using the Sensory Profile (Dunn 1999) as a measure of sensory integration estimate a prevalence of 5–16.5 % (Ahn et al. 2004; Ben-Sasson et al. 2009). This is consistent with the prevalence of DCD which is reported to be between 6 and 22 % (American Psychiatric Association 2013). The incidence of sensory processing problems in children with autism is even higher with estimates of 45–90 % (Ben-Sasson et al. 2007).

Prognosis and long-term follow up of individuals with sensory integration problems has not been examined; however, several studies have found that sensory and motor problems persist into adulthood. Motor difficulties are found to persist well into adolescence (Cermak et al. 1991) and adults with sensory integration problems report higher amounts of depression, anxiety, social isolation, and reduced quality of life (Kinnealey et al. 2011).

ASI may be provided in an outpatient clinic setting or within the school or hospital setting. The ideal setting for ASI is a treatment space that is well equipped with specialized equipment, has an adequate suspension system, and provides the opportunity for a one-to-one therapeutic relationship between child and OT practitioner. Children with mild problems, or those nearing the end of services, may do well in a small group to work on social interaction skills as well as sensory and motor performance. OT practitioners may also provide consultation that includes specific recommendations for environmental modifications or sensorimotor activities performed within the child’s daily routines (sometimes referred to a sensory diet).