In part one of this series hyper-reactivity or over-stimulation of sensory stimuli is described as it appears in many adults with autism. Although hyper-sensitivities are very common in autism, hypo-sensitivities to sensory stimuli can be just as prevalent. Hypo-reactivity exists when the sensory system is under-stimulated by external stimuli, and can create sensory seeking behaviors.
Hypo-Reactivity to Sensory Stimuli in Autistic Adults
Hypo-reactivity to sensory stimuli occurs when the sensory system is under-responsive; the normal processing of smells, sights, sounds, touch, and movement is dulled or under-developed. In this instance the brain is not processing the stimuli correctly. The hypo-reactive individual may fail to recognize stimuli that most would find alarming or strong. They may be unable to identify foods that have gone bad by smell, or have difficulty being able to smell things that are alarming or dangerous such as smoke, noxious/hazardous solvents, or something that is burning on the stove. They may be hypo-sensitive to pain and may barely feel a thing when getting shots, cuts or bruises.Under-responsive individuals can appear lethargic, lazy or unmotivated and be difficult to “get moving.” They may not seem to notice if their hands or face are dirty. They may be able to tolerate many movements without becoming dizzy, but have a hard time feeling parts of their body and knowing where those parts are in relation to the world around them (proprioception) making them clumsy or awkward. Waking up in the morning may also present a problem, as they may not even notice an alarm clock blaring.These individuals can be sensory-seekers, striving to make their sensory systems respond, but requiring stronger stimuli than most.
Sensory Seeking Activities
Sensory seeking activities may be brought about by the individual’s unconscious need to make sense of the world around them. If their sensory systems are under-responsive they may naturally seek out and participate in activities that activate the sensory processing system in the brain. Sensory seeking activities may include a need to fidget and “fiddle” with things all the time. The adult or child with autism may constantly rattle change in their pockets, or keys, tinker with pens, paper clips, rubber bands, or anything within their reach. They may be seen often touching or twisting their hair.Persons with autism displaying hypo-reactivity may be thrill seekers and love fast or dangerous rides, leisure activities, or sports. They may seek out fast, spinning, or upside down carnival rides, will often rock or sway their bodies back and forth, or frequently tip their chair on the back two legs.They may seem restless when sitting through a lecture, presentation or movie, constantly chew on pens, pencils, gum, or smoke cigarettes. Adults and children with hypo-reactivity may prefer foods with strong tastes and flavors, constantly bite nail, fingers, lips, or the inside of their cheeks. They may frequently shake their legs while falling asleep and prefer to sleep with multiple or heavy (weighted) blankets. Cracking knuckles is not uncommon, nor is seeking out crashing or “squishing” activities. Sensory seekers may love crunchy foods like popcorn, carrots, chips, nuts, and pretzels. They may have a need to smell everything judging whether they will like something or someone by smell, and have a supply of scented candles, sprays and perfumes. They may have a need for excessive touching—touching everyone and everything.
An endless combination of symptoms
Adults with autism who are experiencing symptoms of Sensory Processing Disorder do not fit neatly into hypo or hyper sensitive categories. Many times these situations change, and most adults display a combination of hyper (over-stimulated) or hypo (under-responsive) reactivity to the sensory stimuli in the world around them. They can also display sensory seeking behaviors while exhibiting hyper-sensitivities in other sensory areas.
The combinations of signs and symptoms of Sensory Processing Disorder (SPD) that present in autistic adults are endless—as endless as the array of signs and symptoms of Autism Spectrum Disorders. A person with autism can be affected by just one, or all of these sensory processing issues. In addition to hyper-sensitivities, discussed in Part I of this article, SPD can manifest itself in adults in other ways as well. They may have difficulties with sensory discrimination, sensory-based motor skills, emotion and social situations, and internal regulation (discussed in Part III- Additional Difficulties with the Senses).Also see Part III – Additional Difficulties with the Senses