Sensory Integration involves three systems of sensory input and response or interpretation: the vestibular system, which is connected with things like balance, the tactile system which is related to touch, and proprioception, which is one's sense of where one's body and its parts are located in space. People with Asperger's respond differently to sensory input.

Below I discuss these systems and what happens when a person with Asperger's receives stimulation to each one.

The vestibular system coordinates input from a lot of senses. For many with Asperger's, there is a difference in how the input is experienced. Individuals may be hypersensitive to movement. At the other extreme are individuals who have a hypo or under-reactive response to vestibular stimulation; these are the ones who rock, jump, whirl, or, like me, ride roller coasters. Of course, there are also people who have symptoms of both - they struggle with oversensitivity to some types of vestibular input and at the same time seek out intense vestibular stimulation.

In the AS community those who seek out intense stimulation are said to "be stimming." There is a lot of controversy over what behaviors constitute stimming, for example some say that people who twirl their hair are engaging in a mild form of stimming, while others maintain that intensity is a requisite for the behavior.

Here is a very good article on the vestibular system that includes activities for children who have a hypo-active response to vestibular input. The idea is to train the child to accurately interpret and respond to "normal" vestibular stimulation.

I am one of those people who falls into both categories. I used to get extremely carsick and could not use a swing, but I love roller coasters. I am not sure how to explain that as it seems similar to me - most roller coasters (at least the ones I ride) have speeds in excess of 75 miles per hour! When I lived in a big city, I sometimes had a hard time tolerating riding on the train, not because of the forward movement, but because the train car would rock back and forth as it moved.

Besides riding roller coasters, I "stim" by rocking, and by doing kind of a dance step where I step from side to side, kicking my feet against my heels as I do.

Here is a good article on the vestibular system

This has to do with one's sense of touch. Individuals with AS often have issues with texture and touch. Symptoms fall along a continuum that goes from insensitivity to hypersensitivty - to cold, hot or pain, for example. I have extremely high pain tolerance - I have broke a rib and two vertebrae in my back and thought I had strained muscles. On the other hand, I am very sensitive to texture. Fabrics made from synthetics feel like oily plastic to me. I have intolerance of light touch on certain parts of my body. If you ever have bitten a piece of foil by accident, or hit the "funny bone" in your elbow, you will have some sense of what happens to me when someone touches my shoulder. On the other hand, firm touch, as well s deep pressure, feels comforting and good to me.

I tried to educate my work colleagues about my sensory issues because in the crisis and medical fields, people seem to touch each other a lot - for support, to get someone's attention in a noisy environment, and for other reasons I haven't quite been able to fathom. It was hard to get people to believe that I had these sensations. For a while I wore a heavy coat or sweater to mitigate the sensation I had when people touched me. One employee didn't believe me, and one day made literally dozens of excuses to come over to me, and each time he did he touched my shoulder. I asked him not to do it and he kept saying (while grinning) that he forgot. I told my supervisor, who intervened, but before that I tried and tried to tolerate it and ended up near to what we in the AS community call a "meltdown." (see below)

This mouthful has to do with body position. Individuals with proprioception issues may have difficulty locating their own body in space. They may seem clumsy and/or have problems with fine motor skills. Writing, eating or manipulating small objects like buttons may be difficult. It may also be difficult to type, or pick things up. I still have the problem of reaching for something, for example a book on a shelf – and picking up the item next to it.

When I was a child I received extremely poor marks in penmanship; I print better than I write script. When I walk down a hall, for some reason I usually end up against the left wall. I solved this problem by reaching out with my right hand and lightly touching the wall as I walk. This keeps me on the right side of the hall and I don't bump into anything. I generally hold onto bannisters as I walk down stairs as I sometimes don't get how far down to step.

Many "meltdowns" are caused by an overstimulating environment. The stimulation can come from a variety of sources, but the overall effect for someone who is hypersensitive to sensory input is extremely overwhelming. People with AS struggle with social cues and with what is socially appropriate behavior, so someone's response to over stimulation, whether it is to withdraw or engage in vestibular stimulation may be seen as inappropriate.

One of my worst meltdowns came when I was grocery shopping - I was already overwhelmed by too many products in too many aisles as well as loud music where the songs were cut off in the middle for inane announcements from the store's automated commercial ad system. I use the self serve checkout because it's more comfortable than interacting with the store clerks. However this time a well-meaning clerk approached me, and as I was moving slowly, asked me several times if I wanted help. He even tried to take some of the items away from me to help me check out faster. I'm afraid that after the fourth or fifth time that he asked (each time I responded with "No, thank you."), I began yelling "Please leave me alone! Would you just leave me alone!" When I got home I was still shaking and curled up on my couch and rocked until I felt better.