Folk taxonomy

Folk taxonomies are systems of categorization created by non-scientists in order to organize, name, and understand the natural world. Folk taxonomies frequently diverge on some points from the phylogeny established by the scientific study of taxonomy but they also tend to align with scientific classifications on other points: sometimes folk taxonomies lump together many biological species under a single name or place species from several different biological orders in the same group, sometimes there is one-to-one correspondence, and sometimes folk taxonomies differentiate where scientific taxonomies do not. Differentiation between types in folk taxonomies is determined by a wide variety of attributes, some of which may not be immediately obvious to outsiders; morphology and behavior are important but so are the cultural significance and practical utility of the species constituting each group.

Psychological and cultural basis

It is an axiom of modern cognitive psychology, intellectually traceable to Gordon Allport, that humans are innately predisposed to prejudge. Allport believed that categories and "rubrics are essential to mental life" because they allow people to moderate their behavior based on previous experience. Quick responses to environmental stimuli are made possible by broad categories of similar stimuli based on their most pertinent aspects. Highly differentiated categories are less helpful in this respect because they require more effort when it may not be necessary in order to determine an appropriate response.

In a highly influential and oft cited chapter, Eleanor Rosch described the "principles of categorization" that govern the formation of "the categories found in a culture and coded by the language of that culture at a particular point in time." Her first principle followed in Allport's footsteps: organisms, humans included, seek to gain as much information from the environment as possible while exhausting as few cognitive resources as possible. She added a second principle that certain combinations of attributes occur together more often in the perceptual world than do others. This second principle identifies the reason categories work as well as they do; one may make inferences about an environmental stimulus based on its membership in a certain category of similar stimuli.

Even the physical configuration of the brain is compartmentalized; the ability to recognize animate objects, for example, seems to be largely centered in the temporal lobe.