Sensory modulation disorder (SMD) refers to the impairment in detecting, modulating, interpreting, or responding to sensory stimuli. This means someone with SMD would have trouble reacting appropriately due to their perceived intensity of the sensory input. There are three subtypes of SMD: sensory over-responsivity, sensory under-responsivity, and sensory seeking.
Someone who is overresponsive is hypersensitive to different sensations, like sound, touch and movement. Often, they react much quicker, more intensely and for longer to sensory input than someone with a typical responsivity.
Examples of sensory over-responsivity include:
- Avoids group activities, disengages from social activity
- Aggressive or impulsive when overwhelmed by sensory stimuli
- Cautious of trying new things
- Adverse to change
Someone who is under-responsive to sensory stimuli is less sensitive and aware of sensory stimuli. They often appear passive and withdrawn.
Examples of sensory under-responsivity include:
- High pain threshold, so will not notice if they’ve been cut, scratched or hurt
- Unaware that they need to go to the bathroom
- Apathetic and slow to respond
- Difficult to engage in social situations
- Prefers sedentary activity
Someone who is sensory craving actively seeks out sensory sensations, often in ways that may be considered socially unacceptable.
Examples of sensory craving behaviour include:
- Purposely running, jumping and crashing into walls or people
- Intrusive, often touching objects and other people excessively
- Dominant in conversation, often unable to take turns
- Risk taker
- Appears to be unable to sit still, frequently moving