Sensory Channels in Autism

Sensitivity Opens in new window is the higher than “normal”/average degree of being sensitive to something. If I was hypersensitive to sound and stood beside you, I would be able to hear the blood pumping in your veins. We need to understand that the autistic experience of hypersensitivity is right off the end of our scale.

Hypersensitivity and/or Hyposensitivity

In his book The Ultimate Stranger: The Autistic Child, describing possible sensory problems in autism, Carl Delacato (1974) classified each sensory channel as being:

• hyper — the channel is too open, as a result too much stimulation gets in for the brain to handle
• hypo — the channel is not open enough, as a result too little of the stimulation gets in and the brain is deprieved
• white noise — the channel creates its own stimulus because of its faulty operation and, as a result the message from the outside world is overcome by the noise within the system.

Delacato stated that each sensory could be affected in a different way, for example, a child could be hypovisual, “white noise” auditory, hypo- to tastes and smells and hypertactile.

While recognizing the revolutionary contribution to the understanding of autism Opens in new window made by Delacato, it seems necessary to argue one point in his theory.

Delacato considered that a channel could be either hyper- or hypo- or “white noise”. However, it turns out that often one and the same person can experience sensory inputs of one and the same channel at different times from all three of Delacato’s categories — hyper-, hypo-, “white noise” — because the intensity (the volume) with which the channels work often fluctuates.

While describing their unusual sensory experiences autistic individuals prefer the term “hypersensitivity”. This term is very broad.

Here the terms are deliberately narrowed, as it seems more justifiable to distinguish between different sensory experiences, often conventionally covered by one term. Below are some examples of hyper- and hyposensitivities of all the channels experienced by autistic individuals.

Hypersensitivity

1. Hypervision

Hypervision (seeing “invisible”) means that autistic individuals can see more than other people, i.e. their vision is too acute. For example, Alex, an autistic child, often complaints “Moths [air particles] are flying”.

His vision is so hypersensitive that “moths” often become a background with the rest of his environment fading away.

Annabel Stehli (1991, p.186) described her autistic daughter Georgiana who saw “too well” and everything she saw was magnified; “she saw like an eagle”; she saw, for example, every strand of hair “like spaghetti … [that] must have been why she’d been so fascinated by people’s hair”.

Jasmine O’Neill (1999) describes an autistic person as the person who sees what is around him with extra-acute sight.

2. Hyperhearing

Hyperhearing (hearing “inaudible”) is widely reported. Temple Grandin (1996b) describes her hearing as having a sound amplifier set on maximum loudness, and she compares her ears with a microphone that picks up and amplifies sounds. They might be able to hear some frequencies that only animals normally hear (Williams 1992).

Alex, an autistic boy, seems to hear noises before other people. He can announce his dad coming home before anybody else can hear the car turning to the porch.

As noises seem so much louder to him, Alex usually moves away from conversations and avoids crowded places. Children with hyperhearing often cover their ears when the noise is painful for them, though others in the same room may be unaware of any disturbing sounds at all.

3. Hypertaste/Hypersmell

Some autistic individuals have olfactory sensitivities comparable to canines (Morris 1999). For them, ‘almost all types of food smell too sharp” and they “cannot tolerate” how people smell, even if they are very clean. They do not like some food because “the smell or taste” might be intolerable (Rand).

Hypersensitivity to certain stimuli experienced by autistic people can be compared with allergies (O’Neill 1999). Donna Williams’s allergic reaction to some perfumes made the inside of her nose feel like it had been walled up with clay up to her eyebrows, some perfumes “burned her lungs” (Williams 1996).

Some food problems, however, may be caused not by taste or smell but by intolerance of textures of certain food, sounds it produces or even its color. Alex, for example, would never eat any red vegetables or fruit. He would accept a green apple but never a red one!

4. Hypertactility

Hypertactility is very common among the autistic population. Some autistic children pull away when people try to hug them, because they fear being touched. Many children refuse to wear certain clothes, as they cannot tolerate the texture on their skin.

Because their hypertactility results in overwhelming sensations, even the slightest touch can send them to a panic attack. Small scratches that most people ignore can be very painful to them.

Parents often report that washing their child’s hair or cutting nails turns into an ordeal demanding several people to complete it. Luke Jackson (2002), a teenager with Asperger syndrome, describes his autistic brother Ben who has real problems with clothes. Ben will now wear his clothes to go out to school, but as soon as he comes home he cannot help stripping them off — “Hurts!”

For some people it takes many days to stop feeling their clothes on their body. And unfortunately, when this comfortable feeling (or “non-feeling”) has been achieved it is time to wear clean ones, so the process of getting used to its starts again.

Gillingham (1991) states that this “superability” of autistic people, when the senses are so finely tuned that they make them acutely aware of things the “normal” person would not notice, sometimes causes extreme pain. The researcher hypothesizes that to block this pain the body produces endomorphins Opens in new window that, in turn, may suppress further sensory information.

Temple Grandin (2000) suggests that a partial explanation for the lack of empathy in autism may be due to an oversensitive nervous system that prevents an autistic child from receiving comforting tactile stimulation from being hugged.

5. Vestibular hypersensitivity

Vestibular hypersensitivity is reflected in a low tolerance for any activity that involves movement or quick change in the position of the body. People with vestibular hypersensitivity experience difficulty changing direction and are poor at sports. They feel disoriented after spinning, jumping or running. They often express fear and anxiety of having their feet leave the ground. Ayres (1979) termed them “gravitationally insecure”.

Also included in hypersensitivity literatures are proprioceptive signals which come from the sensors on our muscles and integral organs. Proprioceptive hypersensitivity is reflected in odd body posturing, difficulty manipulating small objects, etc.

Hyposensitivity

Hyposensitivity is when the person is not getting enough of the signal to make sense of stimuli. There might be times when they are not getting enough information, then their brain can feel empty and stop processing and they do not really see anything or hear anything. They are just there. Then they might get the information going again in their brain and nervous system by waving their hands around or rocking back and forth or making strange sounds or hitting their head with their hand (Rand).

1. Hypovision

Some autistic people may experience trouble figuring out where objects are, as they see just outlines, and even bright lights are not “bright enough” for them. They may stare at the sun for a long time, or walk around something, running their hand around the edges so they can understand what it is (Rand).

2. Hypohearing

We often see children who “seek sounds” (leaning their ear against electric equipment or enjoying crowds, sirens). They often create sounds themselves to stimulate their hearing — banging doors, tapping things, vocalizing.

3. Hypostaste/Hyposmell

Children with hypotaste/hyposmell chew and smell everything they can get — grass, play dough, perfume.

4. Hypotactility

Those with hypotactility seem not to feel pain or temperature. They may not notice a wound caused by a sharp object or may seem unaware of a broken bone.

5. Vestibular hyposensitivity

Individuals with vestibular hyposensitivity enjoy and seek all sorts of movement and can spin or swing for a long time without being dizzy or nauseated. Autistic people with vestibular hyposensitivity often rock forth and back or move in circles while rocking their body.

6. Proprioceptive hyposensitivity

Individuals with proprioceptive hyposensitivity have difficulty knowing where their bodies are in space; are often unaware of their own body sensations (for instance, they do not feel hunger). Children with hypoproprioceptive systems appear floppy, often learn against people, furniture and walls.

Delacato (1974) was one of the first researchers to suggest that hyper- and hyposensitivity experienced by autistic children caused all autistic behaviors, namely withdrawal from social interaction and communication, stereotypic behaviors (or sims, or self-stimulations).

He called these behaviors sensoryisms (sensorisms: blindisms – visual “isms”, deafisms – auditory “isms”, etc.) and considered them as the child’s attempts to treat himself and either normalize his sensory channels or communicate his problems.

Autistic individuals often describe their stims as defensive mechanisms Opens in new window from hyper- or hyposensitivity. Sometimes they engage in these behaviors to suppress the pain or calm themselves down (in the case of hypersensitivity), sometimes to arouse the nervous system and get sensory stimulation from the outside (in the case of hyposensitivity), and sometimes to provide themselves with internal pleasure.

Very often, therefore, these self-stimulatory behaviors (“sensorisms”), which are defined by non-austic people as “bizarre behaviors” (such as rocking, spinning, flapping their hands, tapping fingers, watching things spin), can be viewed as involuntary strategies the child has acquired to cope with “unwelcome stimulation” (hypersensitivity) or lack of it (hyposensitivity).

That is why, no matter how irritating and meaningless these behaviors may seem to us, it is unwise to stop them without learning the function they serve and introducing experiences with the same function.

The stereotypies caused by sensory hyper- or hyposensitivity can involve one or all senses. If we interpret these behaviors, we will be able to imagine (if not fully comprehend) how the child perceives the world and help the child develop strategies to cope with these (often painful) sensitivities.

In order to recognize the presence of hyper- or hyposensitivities, one should know what signs to look for. Below are some common signs indicating the sensitivities in each sensory channel that can be helpful in compiling a child’s sensory perceptual profile and choosing the methods and environments suitable for each child.

Hypersensitivity can also lead to two different experiences: disturbance by certain sensory stimuli and its opposite — fascination with certain stimuli.

These experiences are very individual. The kinds of stimuli that are disturbing or fascinating vary from person to person. A sight/sound/smell that causes one child pain may be pleasurable to another.

All senses can be affected. Some people might find many noises and bright lights nearly impossible to bear; for others certain noises (children’s voices, car horns, a kettle whistling) and the pitch of some sounds might cause a lot of discomfort.

A woman with Asperger syndrome cannot tolerate somebody whistling. She describes it as a “physical abuse” because whistling causes her body to tremble and even ache. Besides, not only certain sounds but also any sudden unpredictable sounds can be painful.

The fear of noise that hurts the ears is often the cause of many bad behaviors and tantrums. Some autistic children, for instance, can break the telephone because they are afraid it will ring (Grandin 1996b).

In my class there are four children suffering from hyper- or hyposensitivities:

• Alex’s vision is very acute (hyper-): he can see the tiniest particles in the air, the smallest pieces of fluff on the carpet. These experiences distract his attention from whatever he is supposed to do. He hates bright lights and fluorescent light gives him headaches. What makes things even more complicated is that Alex’s hearing is also very acute. He can hear what is going on in the next room but one and always keeps me informed about it — “The chair is being moved. The ruler has been dropped. The bus is coming”, etc.

• Helen’s vision is hypo: she is attracted by any shining object, looks intensely at people (that irritates Alex, who cannot tolerate any direct look at him), is fascinated with mirrors. At the lessons she can move her fingers in front of her face for hours. It seems she cannot get enough visual stimulation and always switches on all the lights as soon as she enters the classroom. (This is usually followed by a fight with Alex who throws a tantrum every time the light is on.) Helen’s hearing is also hypo: she cannot tolerate silence, and if there is not enough noise for her, she would produce sounds herself — banging doors, tapping things, shouting.
• John (hypoauditory) always joins in Helen’s “noise making”. However, his hypersensitivity to smells prevents him coming too close to anybody and makes any activities in the kitche intolerable.
• Vicky is hypersensitive to sounds, touch and smell. If she is being touched by somebody, she immediately smells the place of touch, and more often than not she takes off her jacket or dress with this “spoilt spot” and refuses to wear it again unless it is washed.