A concept can be defined as an idea or mental image that allows for things which share common properties to be grouped together or categorised (Oden, 1987).
Objects which are stereotypical of a particular category tend to undergo faster categorisation, a phenomenon known as the “typicality effect” (Friedenberg and Silverman, 2006). Two conceptual representational models which help to account for this process are the prototype and exemplar theories of concept knowledge.
Prototype Theories
A prototype is an idealised or average representation of properties within a conceptual category that can be used as a reference when categorising various stimuli (Lin and Murphy, 1997).
Picture identification tasks have shown that typicality effects tend to be highest for stimuli which are similar to a prototype, and lowest for stimuli which are dissimilar (Rosch, Mervis, Gray, Johnson and Boyes-Braem, 1976). Word rating tasks have also produced similar results (Malt and Smith, 1984).
One explanation which may account for these findings is that conceptual categorisation occurs as a result of matching the features of a given stimulus to those of a prototype, whereby the more features that are held in common the more prototypical a stimulus appears to be (Smith and Medin, 1981).
Eleanor Rosch has proposed that this categorisation process has a tendency to occur at a “basic level” with single words being used to represent a category (Harley, 2008).
Some studies have shown that this may even be a natural tendency, as when learning to talk children tend to learn basic level terms before they learn subcategory terms that involve the use of multiple words to describe a category (Corter and Gluck, 1992).
This seems to suggest that typicality effects may in fact occur more readily with prototypical stimuli as a result of such stimuli requiring less perceptual processing, whereas dissimilar stimuli, especially those with features that could belong to multiple categories (i.e. featural overlap), require greater perceptual processing, and thus more time, to categorise (Rosch and Mervis, 1975).
Exemplar Theories
An exemplar is a “specific remembered instance” or example of members belonging to, or being representative of, a specific category. The more frequently an item is encountered, the more stored representations (i.e. exemplars) of it will be held in memory (Reisberg, 2006).
This may help to explain typicality effects, such as those observed with picture identification tasks, as items which are most frequently represented in memory are more likely to be recalled due to faster identification and categorisation as a result of requiring less memory search (Rohrer, 2002).
However, although exemplar theories may be similar to prototype theories in the sense that both involve assessing the similarity of a stimulus to a referenced ideal (i.e. a prototype or example) when categorising stimuli, exemplars differ in that they may also be affected by the context of a given situation.
As a result, items displaying high typicality scores under one context, may in fact display lower typicality scores in a different context (Barsalou, 1982). Furthermore, typicality also appears to be influenced by a person’s beliefs or knowledge of the world, and as a result, it is possible that individuals with differing backgrounds may display very different typicality scores for different objects (Murphy and Medin, 1985).
Conclusion
Both prototype and exemplar theories can account for the typicality effects observed in picture identification tasks. Exemplars however, show that the typicality of a given object is not necessarily fixed, but can be altered depending on the context of a situation and a person’s beliefs.
References
Barsalou, L. (1982). Context-independent and context-dependent information in concepts. Memory & Cognition 10, 82-93.
Corter, J., & Gluck, M. (1992). Explaining basic categories: Feature predictability and information. Psychological Bulletin 111, 291-303.
Friedenberg, J., & Silverman, G. (2006). Cognitive Science: An Introduction to the Study of the Mind. Thousand Oaks, CA: Sage Publications.
Harley, T.A. (2008). The psychology of language: From data to theory (3rd edition). Hove, East Sussex: Psychology Press.
Lin, E.L., & Murphy, G.L. (1997). Effects of background knowledge on object
categorization and part detection. Journal of Experimental Psychology: Human Perception and Performance 23, 1153-1169.
Malt, B.C., & Smith, E.E. (1984). Correlated properties in natural categories. Journal of Verbal Learning and Verbal Behaviour 23, 250-269.
Murphy, G.L., & Medin, D.L. (1985). The role of theories in conceptual coherence. Psychological Review 92, 289-316.
Oden, G.C. (1987). Concept knowledge and thought. Annual Review of Psychology 38, 203-227.
Reisberg, D. (1997). Cognition: Exploring the science of the mind. New York: W.W. Norton.
Rohrer, D. (2002). The breadth of memory search. Memory 10, 291-301.
Rosch, E., & Mervis, C.B. (1975). Family resemblances: Studies in the internal structure of categories. Cognitive psychology 7, 573-605.
Rosch, E., Mervis, C.B., Gray, W., Johnson, D., & Boyes-Braem, P. (1976). Basic objects in natural categories. Cognitive Psychology 3, 382-439.
Smith, E.E., & Medin, D.L. (1981). Categories and Concepts. Cambridge, MA: Harvard University Press.
Reviewed – 30th March 2016