CET proposes that underlying intrinsic motivation are the innate psychological
needs for competence and self-deterimination. Accordfing to the theory, the effects
on intrinsic motivation of external events such as the offering of rewards, the delivery
of evaluations, the setting of deadlines, and other notivational inputs are a
function of how these events influence a person's perceptions of competence andl
self-detenmination. Events that decrease perceived self-determination (i.e., that
lead to a more extemal perceived locus of causality) will undermine intrinsic notivation,
whereas those that increase perceived self-detenrination (i.e., that lead to
a m]ore internal net ceived locus of causality) will enhance intrinsic motivation. Furthernore,
events that increase perceived competence will enhance intrinsic motivation
so long as they are accompanied by perceived self-detemination (e.g.,
Ryan, 1982), and those that decrease perceived competence will dininish intrinsic
motivation. Finally, rewards (and other external events) have two aspects. The
iffo nnahional aspect conveys self-deteimined competence and thus enhances
intrinsic motivation. In contrast, the controlling aspect prompts an external perceived
locus of causality (i.e., low perceived self-determ3ination) and thus undermines
intrihsic motivation