What Are Types of Sensory Alterations?

Senses are the tools humans and other animals use to perceive stimuli in the environment. Humans and many other animals possess five senses: sight, sound, hearing, taste and smell. The dominant sense varies from species to species, as does the strength of each individual sense. There are several types of sensory changes or alterations that humans and other animals can experience, with each alteration yielding a different result.

Sensory Deficits

• A sensory deficit is a defect in a sense, such as loss of sight. Organisms can be born with these sensory deficits, they can be the result of age or trauma, or they could be a side effect of a medical condition, such as a stroke. The World Health Organization estimates that blindness and low vision, sensory deficits affecting just the sense of sight, affect more than 300 million people worldwide.

Sensory Deprivation

• As the name would suggest, "sensory deprivation" means depriving the senses of stimuli. It can be as mild as providing monotonous stimuli or as drastic as removing all sensory stimuli for long periods of time. While short periods of sensory deprivation are considered relaxing and may aid in meditation, extended periods of forced deprivation can lead to depression, hallucinations and anxiety. Sensory deprivation involving some of the senses can be accomplished using simple things such as earmuffs, blindfolds or hoods. Full sensory deprivation, on the other hand, requires the use of a chamber or tank especially constructed to provide absolutely no stimuli.

Sensory Overload

• Sensory overload is the opposite of sensory deprivation and involves bombarding the senses with stimuli. When a person can no longer selectively ignore the stimuli, sensory overload is achieved. Sensory overload is unique among other types of sensory alterations in that it is individualized. The amount or type of stimuli required for a person to reach overload varies from person to person. Sensory overload can often be seen in people with sensory processing disorders, including autism. What is considered normal, acceptable stimuli by most people is considered overload to an autistic mind and results in the individual shutting down and avoiding communication with others.

Habituation

• Habituation is a natural process performed by the brain. When a person or animal is exposed to the same stimuli repeatedly, the brain learns to tune it out so it can focus on other stimuli. Since the brain is capable of consciously performing only a limited number of tasks simultaneously, habituation frees the brain to focus on new stimuli. An example of habituation can be seen in squirrels. Rather than processing the sound of the wind each and every time they hear it, squirrels learn through habituation to ignore it to focus on other stimuli that could indicate the presence of danger.