CE Home > Occupational Therapy > OT13 Sensory Processing in Autism

Peter, a 5-year-old boy diagnosed with autism, was integrated into a typical kindergarten classroom. When his teacher first met him, she noticed unexplainable behaviors that were puzzling. He often threw tantrums about his clothes, was anxious standing near his peers, gagged when he ate certain foods, and frequently covered his ears in the classroom. He also played by himself, paced around the room, and enjoyed watching the wheels of toy buses and cars spin for long periods of time. When joining his peers for story time, he abruptly crashed to the floor and spun around on his bottom while the teacher was reading the story. It wasn’t until she consulted an OT that she learned about sensory processing deficits and the huge effect they have on every aspect of Peter’s life.

Peter’s teacher worked with the OT to learn different strategies to help Peter get the sensory experiences he needed to function adequately throughout the day. She found that Peter did best when he was last in line when transitioning around the building; that way Peter could see all of his peers and did not have to worry about classmates bumping into him. Peter seemed to crave deep pressure and heavy work activities, so she gave him special jobs like pushing the lunch boxes down the hallway in a basket. She brought in a trampoline for him to jump on, and they engaged in activities like pushing the walls to make the room bigger. She placed his desk in the front of the room — right in front of where she gave instruction — to minimize distraction. Peter also had noise-reduction headphones that he could wear if he needed them.

Prevalence of Sensory Processing Deficits in Autism Spectrum Disorder

The prevalence of sensory processing deficits in individuals with autism spectrum disorder (ASD) ranges from 69% to 95%, which suggests that sensory processing deficits are a predominant concern within this population.^1-4 Sensory processing impairments include sensory fascinations, sensitivities, and aversions, as well as difficulty integrating and understanding sensory information occurring simultaneously, and can involve multiple sensory systems.^5,6 While the high prevalence of disruptions in sensory processing are recognized problems for individuals with autism, researchers continue to debate how sensory processing deficits are unique to ASD and what the underlying causes are.^3,7 Currently, sensory processing dysfunction is not clearly understood; however, we know that it is not attributable to peripheral sensory deficits (i.e., vision or hearing loss).^8,9

What Is Sensory Processing?

Sensory processing (SP) refers to how the nervous system receives, modulates, and integrates sensory information and, in turn, produces an adaptive response.¹⁰ To function adequately in the environment and participate in activities of daily living, a person must have adequate sensory processing abilities.¹¹ Some individuals with sensory processing deficits can have difficulty in one or more of the following areas: modulating, integrating, organizing, or discriminating sensory input.⁷ Difficulty in sensory processing can affect an individual’s ability to regulate arousal level, attend to relevant stimuli, learn new tasks, sequence tasks, plan motor movements, socialize with peers, and many other aspect of daily performance.

Behaviors occurring in response to sensory processing deficits vary among and within individuals, as well as in severity and type, and are affected by different circumstances. Individuals could have trouble regulating behavioral or motor responses to sensations occurring in the environment and might engage in self-stimulatory behavior to compensate for inadequate sensory processing or to avoid overstimulation.¹² Furthermore, an individual can have varied responses to the same stimulus depending on different circumstances. For example, a child might respond differently to the sound of the fire drill at school depending on the amount of sleep he or she had had the night before, the noise level prior to the alarm sounding, or the people who are present in the room when the alarm sounded. The responsiveness patterns of individuals with sensory processing deficits also can vary within each sensory system.¹³ For example, an individual could be over-responsive (also called hyper-responsive) in the tactile system but under-responsive (also called hypo-responsive) in the auditory system. Changes in the circumstances mentioned above can also affect these variations. Sensory stimuli can elicit increased arousal, avoidance, or fight-or-flight behaviors in over-responsive individuals. One study estimated that 39% of children with ASD are under-responsive to sensation, 20% are over-responsive, and 36% exhibit a mixed pattern of under- and over-responsiveness.¹⁴ 

Impact of Sensory Processing Deficits

Sensory processing difficulties are first apparent during infancy and continue to negatively impact daily functioning as time progresses.¹⁵ These difficulties affect each individual in a unique way. Those who are hyper-responsive to sensory stimuli might avoid unwanted or uncomfortable sensory experiences, limiting their ability to explore and learn from their environment.¹ Others exhibit difficulties with dietary restrictions, sound/noise avoidance/hypersensitivity, texture avoidance during play, excessive seeking of sensory stimuli, unusual preoccupations with smells, and fear of typical activities involving touch, movement, and/or sound. Some individuals display impaired occupational engagement and decreased social participation, which in turn decreases overall quality of life.

Additionally, some individuals exhibit unreliable motor responses, inability to coordinate their bodies, decreased motor imitation, and signs of dyspraxia secondary to sensory processing deficits.¹⁶ Unusual sensory responses can  make it difficult for children to function in their daily environments, including home, school, playground, or a friend’s house. In turn, sensory processing deficits negatively affect peer relationships, learning social norms, attention and focus in school, and familial relationships.

Sensory processing deficits affect not only the individual with the deficit, but often his or her family as well. Family members must accommodate a child’s sensory response patterns and/or reactions to sensory experiences that influence the quality, type, and amount of shared social experiences or family events.

Deficits in sensory processing have also been linked to the core symptoms of ASD, including repetitive behaviors, communication, and socialization deficits.¹⁷ Abnormal sensory processing correlates with the presence of stereotypic, rigid, and repetitive behaviors.^18,19 Additionally, auditory impairments could  negatively affect social development by compounding the language and communication impairment present in individuals with ASD. Sensory processing assessments could be used to screen individuals for early signs of ASD, help tailor individualized intervention programs, and determine both the most effective intervention strategies and at what age to implement them.²⁰

Sensory Processing Throughout the Lifespan

Sensory abnormalities have been well documented throughout the lifespans of individuals with autism.^21-23 Sensory processing deficits emerge early in life and contribute to clinical symptoms associated with ASD.^24,25 A significant amount of SP research is retrospective, such as analyses of early home videos of children later diagnosed with ASD, parent reports, personal accounts, and case studies. Some prospective research includes direct observation and a few randomized, controlled intervention trials.

Home video analysis studies. These studies retrospectively analyze videos of infants who are later diagnosed with ASD. Researchers found that infants with ASD mouth objects more frequently, exhibit social touch aversion, respond to their names less frequently, and display decreased orientation to visual stimuli.²⁰ Osterling and colleagues found similarities regarding decreased response to one’s name, less eye contact, decreased pointing, and decreased showing of objects.^26,27 Additional studies have identified sensory processing differences between infants who were later diagnosed with ASD, infants diagnosed with developmental disabilities, and typical controls.^28,29 Kientz and Dunn compared behaviors of children with ASD to typical controls (ages 3 to 10) and found that the two groups differed on 85% of the Sensory Profile.² Similarly, Gillberg et al. examined a group of children under age 3 who had ASD (N=12) and found that 83% of this group had sensory processing difficulties.³⁰ 

Parent report studies. Another common method of examining sensory processing is parent reports. Caregivers document the frequency of their child’s behaviors in response to sensory stimuli within their typical environment. For example, one study using the Sensory Experience Questionnaire indicated that 69% of children ages 3 to 5 with ASD exhibited sensory processing deficits. In addition, 63% of these children were hypo-responsive to sensory stimuli and 56% were hyper-responsive.24 Using the Short Sensory Profile, another study reported that parents of 26- to 41-month-old children with ASD indicated that their children exhibited taste/smell and tactile sensitivities and under-reactivity more often than typically developing children and children with developmental delays.⁶ Furthermore, the Sensory Profile showed distinct patterns 90% of the time for children with ASD; profiles for this cohort were identifiably different from those for the children with ADHD and the controls.³¹ These patterns of atypical sensory responsiveness have been shown to significantly impair the social interactions of children with high-functioning ASD.³² 

Additional studies using parent reports have identified specific subtypes of sensory processing. The Short Sensory Profile (SSP) has identified three sensory processing subtypes among a group of children with ASD (ages 3 to 10).³³

• Sensory-based Inattentive Seeking (SBIS): This subtype describes those who have typical SP function; however, they have mild difficulties in the domains of Under-responsive/Seeks Sensation and Auditory Filtering domains. These children might touch everything in a room, as if they have no control, or have difficulty focusing on which sounds in a noisy classroom environment they should concentrate on.
• Sensory Modulation with Movement Sensitivity (SMMS): This subtype describes those who have SP difficulties in all sensory domains on the SSP. Individuals in this group show symptoms of under- and over-responsivity within the domains. Because these children might be overly sensitive to touch, they may avoid certain play activities but crave deep-pressure touch, such as a bear hug from their parents. Additionally, they might dislike car rides, yet enjoy spinning around in circles for long periods of time. These children might also enjoy brightly colored objects,
• Sensory Modulation with Taste/Smell Sensitivity (SMT): This subtype describes those who have SP difficulties across all sensory domains in the SSP except Low Energy/Weak and Movement Sensitivity and Extreme Dysfunction in Taste/Smell Sensitivities. These children are usually picky eaters, enjoy excessive movement, are sensitive to certain textures, and gag at certain smells.
• Additionally, researchers have identified that children with ASD have greater difficulty processing auditory information compared with other sensory systems. Children who fit into this SP pattern have trouble modulating and filtering auditory stimuli. 34-36 In fact, one study suggests 100% of children younger than 3 with ASD have auditory processing difficulties that persist through adulthood.³⁰

Personal account studies and case studies. Firsthand accounts help us understand the “lived experience” of having unusual sensory experiences. Personal accounts reported during adulthood have attested to atypical sensory processing in all sensory systems. For example, adolescents and adults with ASD and sensory processing deficits say they have difficulty with academic performance, social relationships, intimate situations, and making career choices.³⁷ College settings and large work environments can cause them to feel emotionally fragile and stressed.³⁷ Additionally, adults who are over-responsive to sensory information report higher levels of anxiety and poor coping skills.³⁷

Neurophysiologic assessment of sensory processing. Researchers outside of the occupational therapy profession have begun to examine the neurophysiology of sensory processing for individuals with ASD. This area of research is in its infancy, but is producing some promising results. Event-related potentials (ERP), magnetoencephalography (MEG), and electrodermal response (EDR) are some of the new neurophysiological tools researchers are using to evaluate sensory processing. MEG recordings of mismatch field (MMF) have been used to indicate disturbances in the ability of individuals with ASD to discriminate the physical properties of two consecutively presented auditory stimuli. Specifically, participants (ages 8 to 32) with ASD exhibited either a significant reduction in amplitude or an absent MMF that differed significantly from the control group.³⁸ One OT has designed methodologies that uses EDR to demonstrate increased  sensitivity to auditory stimuli in young adults with Fragile X Syndrome.³⁹ Another study measured arousal and sensory reactivity of individuals with high-functioning autism and Asperger’s Syndrome using electrodermal activity (EDA). While no significant differences between the two groups using EDA were evident, two patterns of sensory processing were detected: High skin conductance levels indicated high arousal levels and low skin conductance levels indicated low arousal levels.⁴⁰ The research studies mentioned above are finding neurophysiologic differences in the way individuals with ASD process sensory information compared with the control groups. These findings support what OTs see behaviorally (inability to attend to auditory stimuli).

Commonly Used Sensory Processing Assessment Tools

There is little consistency among the tools used to document sensory processing deficits, both clinically and in research. Although the majority of research involving SP and ASD relies on retrospective methodology, studies utilizing prospective designs are becoming more prevalent.

Caregiver Report/Self Report:

• Sensory Profile (SP): The Sensory Profile is a caregiver report that assesses sensory modulation across the lifespan by measuring responses to sensory events in daily life. The SP uses a 5-point Likert scale and contains subsections for each sensory system, in addition to behavioral and emotional responses associated with sensory processing. There are several different age-specific tools, including the Infant/Toddler Sensory Profile (ITSP) for infants (birth through 36 months), Sensory Profile (ages 3 to 10), Adolescent/Adult Sensory Profile (age 11 or older), and Sensory Profile School Companion (ages 3 through 11 years, 11 months). The sensory profile is widely used by researchers because it is easy to administer, provides a z-score for analysis, and has strong internal validity. However, interpretation of the results should be completed only by someone who has  a background in sensory processing.⁴¹
• Sensory Processing Measure (SPM): The SPM is a relatively new caregiver report based on sensory integration theory and designed for use with children ages 5 to 12. It provides norm-referenced standard scores for five sensory systems, including visual, auditory, tactile, proprioceptive, and vestibular, as well as two higher-level functions:  praxis and social participation. The SMP is unique in that it captures multiple environments in the child’s life, including home, main classroom, and a variety of school environments (art, music, gym, recess/playground, cafeteria, bus). Each form takes approximately 15 to 20 minutes to complete and allows the researcher or clinician to evaluate the effect of context on a child’s ability to process sensation and participate in  social situations.⁴²
• The Adult Sensory Questionnaire (ASQ): The ASQ is a self-reporting screening tool for sensory defensiveness in adults. Individuals answer yes or no to items describing sensory defensiveness behaviors. Cut-off scores determine if the individual has sensory defensiveness. This tool is useful for adults who are cognitively able to answer the questions or who have a caregiver who can help them answer the questions.⁴³

Direct Observation Assessments:

• Sensory Integration and Praxis Test (SIPT): The SIPT is a detailed assessment measuring sensory integration and praxis for children ages 4 to 8 years, 11 months. To complete this assessment, a child must have good cognitive and language abilities, be able to follow directions, and be able to pay attention for longer periods of time. Seventeen subtests focus on visual, tactile, kinesthetic, and motor tasks. The subtests have strong inner-rater reliability and validity. Special training is required to administer and interpret the test; administration takes approximately 2 to 2.5 hours. Norms are given for each test, and tests are computer scored using a SIPT CD for a small fee. Because the SIPT requires special training, it hasn’t been used in many empirical studies. However, as OTs move toward evidence-based practice, the SIPT may be used more in the future.⁴⁴
• DeGangi-Berk Test of Sensory Integration (TSI): The TSI is a measure of sensory processing for children ages 3 to 5. The test includes 36 items, with a special focus on postural control, bilateral motor integration, and reflex integration. Administration takes approximately 30 minutes and cut-off scores are available. This assessment is beneficial for children who are able to follow simple directions and attend to short tasks. Professionals using the TSI should be aware that  the normative data was compiled almost 30 years ago (1983).⁴⁵
• Test of Sensory Functions in Infants (TSFI): The TSFI measures sensory processing and reactivity in infants between 4 and 18 months. There are 24 items and five subsections, including reactivity to tactile deep pressure, visual tactile integration, adaptive motor function, ocular motor control, and reactivity to vestibular stimulation. Administration takes approximately 20 minutes and cut-off scores are available. This assessment is one of the only direct-observation sensory processing assessments for infants.⁴⁶

Occupational Therapy Intervention

Regardless of occupation, individuals rely on sensory processing abilities to perform daily tasks. Individuals with sensory processing deficits have problems that disrupt their participation in home, school, and community activities. Occupational therapy uses a holistic approach that incorporates the person, his or her environment, and meaningful occupations; its goal is to improve performance.⁴⁷

The concept and theory of sensory integration (SI) comes from a body of work developed by A. Jean Ayres, an OT and psychologist. As an OT, she was interested in how sensory processing and motor planning disorders interfere with activities of daily living and learning in children.48 Although OTs often use sensory-based approaches to intervention, empirical data supporting this approach is inconclusive. The majority of the research studies supporting its effectiveness consist of lower-level evidence, such as case studies, retrospective reviews, single-subject designs, and personal accounts. Although some studies have an intervention group, the majority have few subjects and often lack a control group. More well-designed, randomized control trials are needed.

OT researchers evaluate the internal and external environments of the individuals we work with and make accommodations as needed.¹³ Our research efforts tend to be holistic in nature, encompassing the person, his or her environment, and his or her occupation.  Our focus is on improving occupational performance, which leads to increased participation in desired occupations and to a higher quality of life for clients. Additionally, our interventions tend to be client centered and incorporate both clients and their families to produce the best outcome and follow-through in the home environment. Future continuing education programs will focus on interventions for autism.

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