Most people have no trouble perceiving and processing the constant barrage of incoming stimuli that target the five basic senses. The human body is so adept at correctly responding to sensory input that people rarely notice when this complicated process is occurring. In individuals who experience perception disorders, however, these internal processors fail to function correctly, resulting in distorted interpretations of what one or more of the five senses perceives. Visual and auditory conditions occur most often, but distortions in the other three senses also can manifest in some people. Perception aberrations occur for many reasons, including because of the presence of neurological disorders, because of inherited genetic abnormalities or as a side effect of injury or illness.
Also known as sensory integration dysfunction, sensory processing disorder (SPD) is one of the most well-known neurological conditions that affect sense perception. SPD can affect a single sense, multiple senses or all five senses, resulting in difficulty processing many types of perceived information that is related to the body and the environment. Typically, people who have SPD are able to perceive this information, but they might not be able to process and respond appropriately to their perceptions. The disorder results in a wide range of responses across affected individuals. For example, one patient might experience overwhelming sensitivity to stimulation of the senses, and another patient might under-perceive most sensory input.
There are many types of visual perception disorders, most of which have symptoms that are easily detectable during childhood. One form of faulty visual perception is difficulty recognizing familiar objects. Despite having previously identified an object, a person who have this disorder might not consistently recognize the item each time he or she sees it. Irlen syndrome, or scotopic sensitivity syndrome, is yet another visual disorder that usually appears during childhood. Often likened to dyslexia, Irlen syndrome causes people to see unusual distortions when they view printed pages.
Auditory processing disorder (APD) affects hearing and usually presents during early childhood. People who experience this condition can usually hear well but might have a difficult time processing and detecting subtleties in sound, especially in a noisy environment. For example, they might confuse the word “chair” with “hair,” or they might hear the word “cow” instead of “couch.” Although the cause of APD remains unknown, many practicing health care professionals believe that neurological conditions can contribute to the disorder. In addition to challenges in communication, APD can result in a wide array of learning disabilities.
Taste, smell and touch are not immune to perception disorders. Some people suffer from central touch conditions that can interfere with their perception of hot and cold as well as the texture, shape or density of objects. Perception disorders that are related to smell and taste are often connected to one another because of the olfactory’s role in how people perceive tastes. Like other sense perception conditions, these disorders can result in total distortion of taste and smell, or they might cause only partial alterations in these two senses.