The Persuasive Power of Knowledge: Testing the Confidence Heuristic

According to the confidence heuristic, people are confident when they know they are right, and their confidence makes them persuasive. Previous experiments have investigated the confidence–persuasiveness aspect of the heuristic but not the integrated knowledge–confidence–persuasiveness hypothesis. We report 3 experiments to test the heuristic using incentivized interactive decisions with financial outcomes in which pairs of participants with common interests attempted to identify target stimuli after conferring, only 1 pair member having strong information about the target. Experiment 1, through the use of a facial identification task, confirmed the confidence heuristic. Experiment 2, through the use of geometric shapes as stimuli, elicited a much larger confidence heuristic effect. Experiment 3 found similar confidence heuristic effects through both face-to-face and computer-mediated communication channels, suggesting that verbal rather than nonverbal communication drives the heuristic. Suggesting an answer first was typical of pair members with strong evidence and might therefore be a dominant cue that persuades. Our results establish the confidence heuristic with dissimilar classes of stimuli and through different communication channels.