The
influence of SI on behavior and social development
Besides sensory processing deficits in discrimination
and perception, there may also be difficulties in regulation of
sensory input. Sensory Modulation is the ability of the brain
to respond appropriately to the magnitude and importance (significance)
of sensory information. For example, if you heard a police siren
approaching you as you drive your car, you would recognize its meaning
(perhaps life and death) and quickly move to the side of the road
to stop.
For some children (and adults),
ordinary, innocuous sensory information (e.g., toilet flushing,
street sounds, restaurant sounds) is perceived as intolerable, noxious,
or even life threatening: they may initiate defensive "fight
or flight" responses. These reactions are called defensive
because the child often perceives the situation as painful or frightening.
When a "fight" response to a nonthreatening sensory
stimulus occurs (e.g., hitting a child who accidentally brushes
against you in line), we describe the child as being hyper-reactive
to the sensory input. We may also describe the child as having
a low-threshhold for sensation. When a "flight"
response occurs, the child may withdraw or not respond to a sensory
event. We may describe this child as hyporeactive or having
a high-threshhold (requiring more or robust input for a neural
response).
There are several explanations
regarding these behaviors that you may wish to read. Please note
the reference list provided and speak with an occupational therapist
trained in SI. Some theorists see modulation as being on a continuum
from hyporeactions to hyperreactions at each end and centering around
typical behavior. Others view response patterns to sensory information
in "bands." Typical children are thought to have a wide
band of appropriate response to sensory information. Some children
with modulation disorders may have a very narrow band for appropriate
response: when challenged with too much input, they will quickly
become hyper-reactive or hyporeactive. Other children may function
primarily in the either the hyporesponsive or hyperresponsive band.
Again, further reading and consultation with a therapist trained
in SI is necessary for comprehensive understanding.
It is important to carefully diagnose
the child's response pattern: if a child becomes overloaded (required
to process too much sensory input), he or she may appear extremely
nonreactive. This is called shutdown.It is most important
to differentiate between withdrawal and shutdown because: behaviorally
they appear to be similar. The intervention strategies are very
different; in severe cases, it could be life-threatening to the
child with shut-down if the wrong one is used.
The first sensory modulation disorder,
Tactile Defensiveness, was identified by Dr. Ayres in the 1970s.
She used the term to describe children who perceived light touch
as uncomfortable or painful. They responded differently from typical
children (e.g., rubbing the area touched to extinguish the sensation,
avoiding the activity or person, asking to stop the sensation).
Some extreme, negative behaviors such as shouting, pushing, and
hitting also have been documented. It is unclear if Sensory Modulation
Disorders are specific to a particular sensory system (i.e., Gravitional
Insecurity may be a defensive reaction because of deficits in
vestibular processing; Tactile Defensiveness occurs when there is
overload in the touch system), or if the behavior is a result of
a summation of input to some or all of the sensory receptors. It
is believed that the behavior may be manifested in any sensory system
(e.g., visual, auditory, touch, etc.). Modulation disorders may
be observed when the child is evaluated using the Sensory Integration
and Praxis Tests (SIPT). However, careful dialogue and special histories
and questionnaires are necessary for diagnosis. . Ongoing research
in the field of occupational therapy is constantly adding to the
knowledge base and strategies for intervention.
The inappropriate and often aversive behaviors triggered
by Sensory Modulation Disorders interfere with development of social
emotional skills and relationships. Children are often unhappy,
inflexible, and limited in their capacity to enjoy the typical pleasures
in life.