Sensory Modulation disorders (SMD)

This refers to a difficulty in modulating the information that comes through the senses. It can be compared to a problem with the volume control on a stereo. If the volume is stuck too high - the stereo will be too loud (hypersensitivity/ defensiveness). If the volume is stuck too low, the stereo will be too soft (hyposensitivity/ low registration). Sometimes children have a problem with a combination of hyper and hypo sensitivities - sometimes the volume is too high and sometimes it is too low. Here, they can also have a problem with thresholds - they can't find the right volume.

These affect the arousal levels of a child and may also affect their hand and body co-ordination, moods, social skills and emotional health.

A) Sensory Defensiveness

This presents as a tendency to react negatively or with alarm to sensory input that most people consider harmless or non-irritating (Wilbarger & Wilbarger, 1991). Many sensations feel too intense and are perceived as a threat.

The child with sensory defensiveness may look at the world as dangerous, alarming or irritating. This often leads to learned patterns and habits to either avoid the disrupting sensations or to seek other sensations that make the child feel better. It can be compared to living in a dark and scary parking lot where a person's protective senses are on hyper-alert, looking for danger". Sensory defensiveness may be mild, moderate or severe.

Level 1 - Mild: While appearing quite 'normal', children might be described as picky, oversensitive, slightly overactive, resistant to change and slightly controlling. They may act mildly irritated by some sensations, but not all. They may be particular about clothes and/ or foods. They may have to use enormous control and effort to succeed in social relations, and when they can no longer maintain the level of effort, they may fall apart emotionally under apparently little or no stress (Wilbarger & Wilbarger, 1991).

Level 2 - Moderate: This level affects two or more aspects of a child's life. Children have difficulty with social relations - either overly aggressive or isolating themselves from peers. Self-care skills are disrupted. Difficulty with attention or behaviour in school is often noted. Explorations and play may be limited due to fearfulness of new situations or resistance to change (Wilbarger & Wilbarger, 1991).

Level 3 - Severe: this level affects every aspect of a child's life. These children usually have other diagnostic labels for various areas of dysfunction such as severe developmental delay, autism or emotionally disturbed. Strong avoidance of some kinds of sensations or intense sensory seeking is often observed. Treating the sensory defensiveness first, reduces the sensory problems and increases the effectiveness of other forms of intervention (Wilbarger & Wilbarger, 1991).

Children with defensiveness will often have other difficulties with behaviour, emotional stability (regular tantrums or melt-downs), excessive shyness, avoidance of eye contact, gross motor co-ordination (use of the large muscles of body such as legs, trunk, arms for running, swimming, jumping, catching balls) and fine motor coordination affected (small muscles of the hand for tasks such as buttoning, cutting, craft and handwriting).

It is best to identify and treat the defensiveness first as this gives a clearer picture of the other issues and increased the effectiveness of other interventions (Wilbarger & Wilbarger, 1991).

Suggested Programs

B) Low Registration

Many sensations are either slow to be perceived or not perceived at all. The child therefore needs much more stimulation than normal to perceive sensory stimulation. Such a child will tend to appear tired, lazy, daydreamy and unmotivated. After much activity, children with "low registration" appear at their best. Children with low registration will mostly have low muscle tone, decreased balance, low hand and body awareness, with resulting gross and fine motor skill problems.

Suggested Programs

C) Sensory Seeking

A child who is sensory seeking may have either sensory defensiveness, low registration or a combination of both. The sensory seeking child seeks more intense sensations, more often and for longer durations than most other children. This is generally to help the child get the right type and amount of sensory information to organise his or her nervous system and body.

Suggested Programs:

As per first 2 issues depending on need.

D) Narrow thresholds

Children appear to fluctuate between tired, lazy and unmotivated to hyperactive and unable to keep still or angry and out of control. There seems to be a very narrow band of "good" or "just right" function.

Suggested Programs:

As per first 2 issues depending on need.


These issues can affect all or just a few of the sensory systems.