VESTIBULAR SYSTEM: The sensory system that responds to the position of the head by way of semi-circular canals in the inner ear. Inside the canals is fluid that stimulates cells when the head moves in different speeds and directions. This is how the body deals with movement and gravity, and the level of awareness typically is subconscious unless very intense. When dysfunctional, the person seems to be more aware or less able to deal with imposed movements, like having motion sickness to a mild degree.

VISUAL PERCEPTION DYSFUNCTION: Several subskills are not fully developed and can interfere with finding things in a draw or room, using space wisely on an empty page of paper, forming numbers and letters appropriately, sequencing steps to an activity or following the written steps on paper.