In search of reliable persuasion effects: III. The sleeper effect is dead: Long live the sleeper effect.

The sleeper effect in persuasion is a delayed increase in the impact of a message that is accompanied by a discounting cue. Despite a long history, the sleeper effect has been notoriously difficult to obtain or to replicate, with the exception of a pair of studies by Gruder et al. (1978). We conducted a series of 16 computer-controlled experiments and a replication of the Gruder et al. study to demonstrate that a sleeper effect can be obtained reliably when subjects (a) note the important arguments in a message, (b) receive a discounting cue after the message, and (c) rate the trustworthiness of the message communicator immediately after receiving the discounting cue. These operations are sufficiently different from those used in earlier studies to justify a new differential decay interpretation of the sleeper effect, in place of the dissociation hypothesis favored by most previous sleeper effect researchers. According to the differential decay interpretation, a sleeper effect occurs when message and discounting cue have opposite and near-equal immediate impacts that are not well-integrated in memory. The effect occurs, then, if the impact of the discounting cue decays faster than that of the message.