The proprioceptive system refers to components of muscles, joints, and tendons that provide a person with a subconscious awareness of body position. When proprioception is functioning efficiently, an individual’s body position is automatically adjusted in different situations; for example, the proprioceptive system is responsible for providing the body with the necessary signals to allow us to sit properly in a chair and to step off a curb smoothly. It also allows us to manipulate objects using fine motor movements, such as writing with a pencil, using a spoon to drink soup, and buttoning one’s shirt. Some children can have a difficult time registering proprioceptive information and they may excessively seek it out.

The vestibular system refers to structures within the inner ear (the semi-circular canals) that detect movement and changes in the position of the head. For example, the vestibular system tells you when your head is upright or tilted (even with your eyes closed). Dysfunction within this system may show itself in two different ways:
1.) Some children may be hypersensitive (overly sensitive) to vestibular stimulation and have fearful reactions to ordinary movement activities (e.g., swings, slides, ramps, inclines). They may also have trouble learning to climb or descend stairs or hills; and they may be apprehensive walking or crawling on uneven or unstable surfaces. As a result, they seem fearful in space. In general, these children appear clumsy.
2.) On the other extreme, the child may actively seek very intense sensory experiences such as excessive body whirling, jumping, and/or spinning. This type of child demonstrates signs of a hyposensitivity (decreased sensitivity) to vestibular input; that is, they are trying continuously to stimulate their vestibular systems.

The tactile system includes nerves under the skin’s surface that send information to the brain. This information includes light touch, pain, temperature, and pressure. This also includes our response to the temperature and consistency of food. All this information plays an important role in perceiving things in the environment as well as protective reactions. Both over sensitivity and decreased awareness of tactile input is possible. Tactile defensiveness is a condition in which an individual is extremely sensitive to light touch input. Theoretically, when the tactile system is immature and not working improperly, abnormal neural signals are sent to the brain which can interfere with other brain processes. This, in turn, causes the brain to be overly stimulated and may lead to excessive brain activity, which can neither be turned off nor organized. This type of over-stimulation in the brain can make it difficult for an individual to organize one’s behavior and concentrate and may lead to a negative emotional response to touch sensations.
The gustatory system is responsible for our response to the taste of food. The tiny bumps on the tongue register information such as if the food is salty, sweet, sour, bitter, or savory.

The auditory system refers to our hearing system. There are several tiny structures in and around our ears that play important roles in how take in sound information as well as movement information. Sometimes children with poor vestibular functioning have a history of ear infections. Also, children with processing delays can show either sensitivities or increased tolerance for auditory input.

The visual system is our sensory system responsible for sight. Our visual system also has a close relationship with our vestibular system.

The olfactory system is our sensory system responsible for what we smell. While this system tends to be the least impacted by sensory processing delays, we often see sensory sensitivities to noxious smells in children with processing