Sleeper Effect

A psychological observation that a persuasive message can attain *more* credibility by a person over time if it's (counter-intuitively) accompanied by a 'discounting cue' (something that ought to diminish the credibility or provides a disclaimer of the message, as opposed to a message without such a cue. An example would be something like the statement, "you eat eight spiders per year in your sleep," which has dubious credibility, yet is prone to belief over time as a result.