Describe the three sociological models of fashion described in the text.

Economic models of fashion: Economists approach fashion in terms of the model of supply and demand. Items that are in limited supply have high value, while those readily available are less desirable. Rare items command respect and prestige. Thorstein Veblen's notion of conspicuous consumption proposed that the wealthy consume to display their prosperity, for example by wearing expensive (and at times impractical) clothing, or displaying their time for leisure and buying power by being overweight.
Sociological models of fashion: The collective selection model is an example of a sociological approach to fashion. This perspective focuses on the initial adoption of a fashion (idea, style, etc.) by a subculture and its subsequent diffusion into society as a whole. Such diffusion often begins with youth subcultures such as the hip-hop segment.
A "medical" model of fashion: For years lowly ballet flats were shoes for dancers. Suddenly the shoe became a fashion statement even though nothing was done to promote this product. Why did this style diffuse through the population so quickly? Meme theory has been proposed to explain this process using a medical metaphor. A meme is an idea or product that enters the consciousness of people over time-examples include tunes, catchphrases ("You're Fired!") or styles like ballet flats. In this view, memes spread among consumers in a geometric progression, just as a virus starts off small and steadily infects increasing numbers of people until it becomes an epidemic. Memes "leap" from brain to brain via a process of imitation.