Categorical perception is when categories understood by a human or other animal can change the perception of things in the same class. Scientists have found that people often perceive things more accurately when concepts such as words or pictures are in different categories. Things in the same category are often mis-perceived because their differences are not as obvious. Differences that are within the same category are often clustered together; however, differences in concepts between two categories tend to be more readily noticed. Studies have also tried to determine if categorical perception is learned or it is innate, or built into the brain.
The categories generally have to be understood in comparison to a relative idea. All of the visible colors of the light spectrum, as seen on a rainbow, are recognizable regardless of what a language calls the colors. Some theories of perception try to explain how definite things are recognized in different ways. The Whorf Hypothesis sought to prove colors were categorized based on their names. In the late 1960s, researchers determined that whether languages expressed colors similarly or differently, the visual perception was generally similar.
With speech, categorical perception usually helps people recognize words even though vowels may be pronounced differently. Perception can also be influenced by the size and color of drawings, or the appearance of objects or animals in a picture. Researchers modeling the concept have tried to decide on whether people categorize based on what is most typical, or by features that are not typical to a group. Categorical perception can depend on what someone uses as a reference point, whether typical or atypical features are the focus.
Computational methods have been developed based on the psychology of perception. Researchers often use computers to mathematically represent cognition and learning. Neural imaging can show the effects of stimuli before and after someone learns something. Correlating categorical perception with brain activity sometimes shows that perceptions can be changed when a person learns something new. The concept in general may offer insight into how the brain organizes sensory information.
Categorical perception can take information from various senses and symbolize it. This can make the information more predictable for the brain to process. Perception can be influenced by many languages because general words are often given to multifaceted concepts. Organizing many things in the world into such categories can change how physical objects and abstract ideas are perceived to people.