Sleeper effect is a term used in several different senses in the social psychology of attitude change. Its most frequent usage is probably in describing a change in an attitude or opinion after a study has been conducted. This may be one reason for inaccuracy in public opinion polls. The term is also used to describe a more favorable response to a communication after some time has elapsed, rather than the expected decline in the effect of the communication. Sleeper effect is also used to describe the dissociation between communication and communicator over time so that people may become less receptive to positive sources and more receptive to negative ones.
Definition