Prototype Theory: An Overview

Prototype theory examines how exposure to different visual representations affects the way in which individuals categorize different objects and images. According to prototype theory, humans use a concept known as a prototype to classify the objects they encounter. These prototypes are images stored in a person's memory, and each prototype represents an overall class or category of objects. Individuals use these prototypes to determine if a certain item belongs to a particular category or class of objects (e.g., Does this object belong in the category of 'car' or to the category of 'boat?') (Aitchison, 1994; Ross & Makin, 1999).

Prototype-based categorization involves a process in which new objects/images are compared to different prototypes in an individual's memory. The process works as follows : Each prototype (visual representation) is made up of a series of features, or characteristics . Individuals use these characteristics as criteria for defining the traits an item needs to possess in order to be considered part of a particular class or category of objects (Aitchison, 1994; Ross & Makin, 1999). Whenever an individual encounters something new, that person compares the characteristics of the new object to those of all of the different prototypes in his or her memory (Aitchison, 1994; Ross & Makin, 1999). New objects that share enough characteristics in common with a particular prototype will be classified as belonging to the overall category represented by that prototype. So, if a hammer is the prototype I use to represent the category of 'tool,' then the more an object resembles a hammer (the more visual characteristics it has in common with a hammer ), the more likely I am to classify that object as a 'tool.'

This concept of categorization based on similar characteristics helps account for famous miscategorizations often made by children. For example, many children first characterize dolphins as 'fish.' Such mistakes result from the fact that dolphins have many visual characteristics in common with a prototypical fish (e.g., fins and a tail for swimming) and few characteristics in common with most persons' prototype for mammal (e.g., walks on two or four legs and has fur). Because the visual characteristic of a dolphin match with prototypes for fish and mismatch with prototypes for mammal, an incorrect categorization is made.

This example of miscategorization is important, for it reveals that prototypes do not arise randomly . Rather, they often result from repeated exposure to items over time (Aitchison, 1994). The more one sees a particular object, like a robin, the more likely that individual is to make ' robin ' his or her prototype for representing the category of 'bird.' Once such an association is formed , the individual will use the characteristics of that prototype to identify other objects as 'birds.'

While prototype theory is abstract, its central notion (that humans use ideals and characteristics to classify objects) can help marketers design more effective online visuals for international audiences. Additionally, some evidence indicates that different cultural prototypes can result in the misinterpretation of images. In their discussions of imagery related to international health education, both Linda Driskill (1996) and Deborah C. Andrews (1998) note how cultural ideals for what a 'standard' home should look like can result in recognition and interpretation problems in image-based instructions. As a result, the usability and the credibility of the related materials could be called into question.