Sensory Integration Dysfunction and Sensory Processing Disorder (SPD)

If any sense is inefficient, the integration process can be disrupted, and Sensory Integration Dysfunction (SID) – a term coined by A. Jean Ayres PhD – occurs. 

However, because of the possibility of confusing it with the unrelated disorder Sudden Infant Death Syndrome (SIDS), in the 1980s, those in the field informally began using the term DSI for dysfunction in sensory integration.

Ayres Sensory Integration

Ayres Sensory Integration® (ASI) is now trademarked, and includes the original theory, assessment, patterns of dysfunction, and intervention concepts, principles, and techniques articulated by Dr. Ayres and applied by therapists trained in this approach worldwide.

Some of Dr. Ayres’ colleagues and students, headed by Susanne Smith Roley OTD, OTR/L, FAOTA and Zoe Mailloux, OTD, OTR/L, FAOTA, founded a new organization called The Collaborative for Leadership in Ayres Sensory Integration (CLASI).

CLASI provides continuing education opportunities for mastering, applying and advancing knowledge in ASI theory and practice, culminating in a certificate of certification. 

CLASI is a member of the International Council for Education in Ayres Sensory Integration (ICE-ASI) which provides standards for education in ASI around the world.

Recently, a small group of occupational therapists, led by sensory integration researcher Lucy Jane Miller, PhD, OTR, have suggested some new terminology: Sensory Processing Disorder, or SPD, as an umbrella term encompassing several types of sensory issues.

A long-term goal of this movement is to include SPD in the Diagnostic and Statistical Manual of Mental Disorders (DSM); this effort failed, however, for the fifth edition.

Hypo- and Hyper-Reactivity

Ayres speculated that children with Sensory Integration Dysfunction fell into one of two categories:

  • Those who are under- (hypo-) reactive to stimulation and seek sensory experiences
  • Those who are over- (hyper-) reactive to sensations and show defensive behaviors

Contemporary research supports Ayres’s theory and suggests that inconsistent sensory responses are due to either overly high thresholds for sensory input (hypo-) or sensory defensiveness (hyper-).

She further proposed that the abilities of those in both categories to register and modulate sensory stimuli varied from time to time and in different environments.

Possible offenders in the environment that could trigger a defensive response from those with Sensory Integration Dysfunction and/or Sensory Processing Disorder include (list provided with permission from The HANDLE Institute:

  • Their own clothing:
    • Stiff tags
    • Stiff fibers (e.g., jeans)
    • Seams in socks
    • Waistbands and belts
    • Jewelry
    • Hairbands
    • Synthetic fibers
  • Clothing on others:
    • Synthetic fibers
    • Intricate patterns
    • Metallic look
    • Reflecting accessories (e.g., sequins, watches)
    • Noise makers (e.g., “bangle jangle” bracelets, watch alarms)
  • Odors:
    • Paints, varnishes, glues
    • Room fresheners
    • Cologne, perfume, aftershave
    • Hair spray, gels, etc.
    • Clothes that have been drycleaned
    • Fabric softeners applied in the dryer
    • Orange peel, banana peel
    • Synthetics (e.g., plastic food packaging)
    • Fatty foods (e.g., broiled chops)
    • Extremely sweet odors
    • Extreme or unexpected body odors
  • Lighting:
    • Fluorescent lights
    • Halogen lights
    • Strobe lights
    • Flickering sunlight (e.g., through leaves and blinds)
    • Severe contrast (e.g., stage productions)
    • Lighted mirrors
    • Reflective materials
    • Certain colors (especially yellow-orange)
    • Color contrasts (e.g., red and black)
    • White paper (especially glossy magazines)
    • LCD signboards
    • Automobile lights at night or in the rain
    • Automobile lights in white-tiled tunnels
  • Sounds:
    • Unexpected loud sounds
    • High-pitched sounds
    • Deeply resonating sounds
    • Disharmonious sounds
    • Background conversation
  • Body-in-space situations:
    • Light contact with seat, ground
    • Slightly tipped/irregular surfaces
    • Swivel chairs
    • Open areas behind one’s back
    • Close quarters
    • Remaining seated while others move past
    • Playground equipment (swings, slides, merry-go-rounds)

Sometimes when multiple sensory stimuli compete for the body’s attention, one sense may be hyper-responsive, while another may under-respond; there are an infinite number of sensory combinations.

For instance, a child who is tactilely defensive on a “bad” days and screams blood murder at the hairdresser may tolerate a haircut if he or she is feeling more organized on another day.

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Sources & References

Ayres, A.J., et al. Hyper-Responsivity to Touch and Vestibular Stimuli as a Predictor of Positive Response to Sensory Integration Procedures by Autistic Children. American Journal of Occupational Therapy, June 1980, Vol. 34, 375-381.

Baranek, G.T., et al. Tactile Defensiveness and Stereotyped Behaviors. Am J Occup Ther 1997 Feb;51(2):91-5.