Researchers display confirmation bias when they persevere by revising procedures until obtaining a theory-predicted result. This strategy produces findings that are overgeneralized in avoidable ways, and this in turn hinders successful applications. (The 40-year history of an attitude-change phenomenon, the sleeper effect, stands as a case in point.) Confirmation bias is an expectable product of theorycentered research strategies, including both the puzzle-solving activity of T. S. Kuhn's "normal science" and, more surprisingly, K. R. Popper's recommended method of falsification seeking. The alternative strategies of condition seeking (identifying limiting conditions for a known finding) and design (discovering conditions that can produce a previously unobtained result) are result centered; they are directed at producing specified patterns of data rather than at the logically impossible goals of establishing either the truth or falsity of a theory. Result-centered methods are by no means atheoretical. Rather, they oblige resourcefulness in using existing theory and can stimulate novel development of theory.

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 Cruder et al. (1978). We conducted a series of 16 computer-controlled experiments and a replication of the Cruder 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 wellintegrated in memory. The effect occurs, then, if the impact of the discounting cue decays faster than that of the message.A sleeper effect in persuasion is a delayed increase in the impact of a persuasive message. The term was first used by Hovland, Lumsdaine, and Sheffield (1949) to describe opinion change produced by the U.S. Army's Why We Fight films used during World War II. As a pattern of data, the sleeper effect is opposite to the typical finding that experimentally induced opinion change dissipates over time . As such, the sleeper effect is an "interesting quirk" that has attracted much research and textbook attention.Early in its history, the sleeper effect became identified with the dissociation hypothesis and was denned as a delayed increase in persuasive impact that occurs as a result of a persuasive message accompanied by a discounting cue. Close scrutiny of previous sleeper effect research, however, reveals that much Figure 1C), although taking the form of a delayed increase in agreement with the communication, is conceptually more similar to decay of (negative) persuasion than it is to the sleeper effect.

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Although Janis's concept of groupthink is influential, experimental investigations have provided only weak support for the theory. Experiment 1 produced the poor decision quality associated with groupthink by manipulating group cohesion (using group labels) and threat to group members' self-esteem. Self-reports of some groupthink and defective decision-making symptoms were independently, but not interactively, affected by cohesion and threat. Experiment 2 confirmed the success of the cohesion manipulation. Experiment 3 replicated the poor-quality decision making observed in Experiment 1 and provided support for a social identity maintenance perspective on groupthink: Groups who operated under groupthink conditions but who were given an excuse for potential poor performance produced significantly higher quality decisions than groups who worked under groupthink conditions alone. The results are used to interpret the groupthink phenomenon as a collective effort directed at warding off potentially negative views of the group.

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