The British Psychological Society

THE BRITISH PSYCHOLOGICAL SOCIETY

QUINQUENNIAL CONFERENCE

Psychology for the 21st Century

30th March – 2nd April 2005, University of Manchester

ABSTRACT

Authors & Affiliation. / B.D. PULFORD, A.M. COLMAN, University of Leicester.
Title / Testing the confidence heuristic: Are confident communicators more persuasive?
Content. / According to the confidence heuristic proposed by Thomas and McFadyen (1995), when people communicate beliefs to one another, they tend to express degrees of confidence proportional to the certainty with which they hold those beliefs. Further, recipients tend to judge the reliability of the communicated information according to the confidence with which it is expressed. Thomas and McFadyen also showed theoretically that the confidence heuristic permits efficient exchange of information between decision makers with common interests, and that it reliably implements optimal solutions to pure coordination games of incomplete information -- games in which the players’ interests coincide, so that they are motivated to coordinate their actions, but they have incomplete information about the payoffs associated with the possible outcomes. Our research focused on such games in an attempt to empirically test if there is evidence to support this theory.
Working in dyads on the ‘Police and Suspects Problem’, 56 participants attempted to determine which face, from an array of 9 photos, looked most like the suspect portrayed in an E-fit. On each trial, one participant was given a very good e-fit likeness of one of the faces, designed to induce high confidence and high accuracy, while the other participant was given a weak e-fit likeness of one or more of the other faces in the array. Participants were not allowed to see each other’s e-fits but were allowed two minutes to discuss each e-fit and which suspect they wanted to choose. The strong evidence was given to one player on 8 of the trials and to the other player on another 8 of the trials; the same e-fits were used twice, shown once to player 1 and later on in the session to player 2. By this method the same e-fit faces were shown to both partners, so the number of times that the strong evidence player won the argument could be determined. On each trial, if both players chose the correct face they were paid 40p each. If they both chose the same, but incorrect, face they received 20p each. If they chose two different faces, then they each were paid nothing, even if one chose the right face. The players also indicated on a 0-100 scale how confident they felt that they had selected the correct person. The gender of the player and their partner’s gender was investigated, as were individual differences such as assertiveness, need for cognition, need for closure and overconfidence.
Results: Players disagreed with each other less than 8% of the time, and half of the pairs never failed to reach agreement with each other, indicating that they understood the parameters of the game. The number of times that the person with the strong evidence persuaded the other to agree on the correct face was significantly higher than the number of times the person with the weak evidence persuaded the one with the strong evidence to agree on the incorrect face. This is evidence for the operation of the confidence heuristic, but since the person with weak evidence quite frequently was persuasive, the communication of confidence is obviously not simple, and other factors mediate the use of the heuristic in some decisions.

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