Sensory Processing

We are all aware of the senses of sight, hearing, taste, and smell, but sensory processing involves three additional specialized sensory systems which are very powerful and influence how effectively we detect and make sense of vestibular, tactile, and proprioceptive information. This is the information that enables us to feel safe and secure, to direct and sustain our attention, to move without fear, and to use our bodies automatically to perform the myriad of motor tasks we take for granted throughout our normal daily routine. When there are problems in these specialized systems, the individual gets distracted by information that should be taken for granted. The effectiveness of a person's sensory processing is evaluated in part by interpreting behavioral indicators such as self-stimulation and how a person responds to common every day tasks, interactions, and requests. It is helpful to know what each specialized sensory system does because individuals with sensory processing disorders may have deficits affecting one or more of these systems.

The vestibular system has its receptors in the inner ear and senses movement of the head in all planes. The sensory input we get throughout the vestibular system tells us exactly where we are in relation to gravity, whether we are still or moving, how fast we are going, and in which direction. Through its influence on muscle tone the vestibular system effects posture and movement. The vestibular system also plays a crucial role in the development of visual spacial skills and eye-hand coordination skills.

The tactile system contains touch receptors located in and just under the skin. This system defines our body's boundaries and differentiates light touch from deep pressure touch sensations. Light touch has a rapid diffuse spreading effect and alerts the nervous system to be wary of possible danger. Pressure touch calms the nervous system. It provides a localized, precise sensation which enables us to tell shapes, textures, and sizes of hand-held objects without looking at them. The tactile system has a profound influence on our ability to learn. Defensiveness to touch is a serious problem that creates a significant barrier to a person's ability to benefit from all other treatments and programs.

The proprioceptive system has its receptors in muscles, tendons, and joints. Sensory information from this system is created by the contracting and stretching of muscles and by the bending and straightening, pulling and compression of joints between bones. This information is being constantly sent to the brain so that it can keep track of where all our body parts are and what they are doing without our having to look at them. Adequate integration of proprioceptive information is crucial to our having a physical sense of self upon which we can base a psychological sense of self-awareness. Proprioceptive input helps integrate other types of stimulation such as vestibular and tactile and aids in organizing behavior.

The three sensory systems play a major role in the development of muscle tone, motor skills, self-awareness, and the ability to meaningfully interact with others. Deficits can have a profound effect on arousal, alertness, and self-regulated behavior. These systems, collectively, are also important for the development of eye-hand coordination, visual perception, learning capacity and academic achievement, self-esteem, self-control, and self-confidence. Sensory input to the three systems is so vital to brain function that people with disordered sensory processing often develop compensatory behaviors to obtain needed sensation. Compensatory behaviors are typically beyond a person's control and they tend to persist until the needed sensation can be obtained in another way.