[1] There are multiple well-documented effects of age stereotypes on a number of cognitive and physical outcomes (including memory, cardiovascular reactivity, and longevity).
According to Levy (2009): "The theory has four components: The stereotypes (a) become internalized across the lifespan, (b) can operate unconsciously, (c) gain salience from self-relevance, and (d) utilize multiple pathways.
[6] This process of early internalization is facilitated by the lack of resistances that are usually present when stereotypes are relevant to the personal identity of those exposed to them.
[3][8][9][10][11] This process continues on into early adulthood, where the acceptance and invocation of negative age stereotypes may represent short-term benefits in the form of greater social and economic resources being allocated to younger, rather than older, adults.
For instance, a 1990 study by Purdue and Gurtman demonstrated that the associations made by their college-aged participants between certain negative traits and old age had an "automatic" component, such that, when their participants were subliminally primed (i.e., presented with stimuli at speeds sufficient for perception, but not recognition) with the word "old", they made associations with negative traits significantly faster than when they were subliminally primed with the word "young".
Levy (2003), in paraphrasing Snyder and Miene (1994), notes that "the old is the only outgroup that inevitably becomes an ingroup for individuals who live long enough" (pp. 33–54).
For example, in a large longitudinal study of twenty years, Levy and colleagues found that those with more positive self-perceptions of aging at baseline tended to have better functional health and greater longevity.
Unlike SET, STT attempts to explain these outcomes solely as a result of individuals' reactions against negative stereotypes directed at them from external sources.
In contrast to the theoretical assumptions laid out by STT, several lines of research have produced findings that support SET's suggestions that age stereotypes are internalized, can exert an effect regardless of the target's awareness, are effective in both negative and positive formulations, and can operate across the lifespan.