(From Sensational Kids, Miller, 2006)

Sensory Modulation Disorder is a chronic and severe problem involving the ability to turn sensory information into behaviors that match the nature and intensity of the sensation. Children with difficulties modulating sensory input may under-respond to sensation, over-respond to sensation, seek intense sensation, or display a mixture of the three. Sensory modulation difficulties can occur in any of the seven senses [visual, auditory, gustatory (taste), olfactory (smell), tactile (touch), vestibular (movement and relation to gravity) and proprioceptive (position of joints and muscles)].

Children who over-respond to sensory information (also referred to as sensory defensiveness) experience sensory messages more intensely, more quickly, and/or for a longer time than most children with normal sensory responsivity. These children are often in a state of high arousal. Sensations that most individuals would find innocuous or even pleasant, these children might find noxious or painful. As a result, these children often become anxious in certain sensory environments and situations. Unexpected disruptions in their environment can set off crying, screaming, and tantruming that seems overly dramatic and extreme. Children with sensory defensiveness often seem rigid in their routines in order to control their environment and avoid unexpected sensory experiences that have the potential to lead to some new insult to their senses. Two common examples of over-responsivity to sensory information are tactile defensiveness and gravitational insecurity; however hypersensitivity to sensory information can occur in any sensory system. A child with tactile defensiveness may have trouble with common everyday activities such as hugging, hair washing, teeth brushing, eating foods of various textures, or falling asleep at night. Children who are gravitationally insecure frequently avoid movement activities and seem earth-bound; playgrounds are especially frightening.

Children who under-respond to sensory information exhibit less of a response to sensory information than the situation demands, taking longer to react and/or requiring relatively intense or long-lasting sensory messages before they are moved to action. These children often fail to notice when they bump or bruise themselves and are often reported by their parents to have a high tolerance for pain. They usually prefer to be sedentary and demonstrate low arousal. Frequently, these children seem unaware of activity around them, of someone talking to them, of someone/something touching them, of food or liquid left on their face after eating, and of their own body sensations (such as hunger, hot/cold, urge to use the bathroom).

Children who are sensation seeking have a seemingly insatiable craving for sensory experiences and actively seek sensation, often in ways that are socially unacceptable and frequently dangerous. Sensory seekers frequently display high arousal. Some level of sensation seeking is normal for children, but children with sensory modulation difficulties are extreme in the amount and intensity of their seeking. Many of these children seem to be constantly moving and have difficulty sitting still. This especially becomes a problem in school, and these children are frequently misdiagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). They are often labeled as “bad”, “troublemakers”, and “dangerous”. Socially, they tend to be invasive, getting too close to people and accidentally running into and knocking other children over. Sensation seeking is not limited to movement. Children might seek intense flavors and spiciness, listen to music at ear-splitting levels, or constantly touch objects or people.