Motivational Bias in Criminal Investigators' Judgments of Witness Reliability1

An experiment was conducted where experienced criminal investigators (N = 49) evaluated the testimony of a witness who either confirmed or disconfirmed the focal hypothesis in a homicide case. Participants' motivation to perpetuate the hypothesis was manipulated by varying the need for cognitive closure via time pressure. The hypothesis‐inconsistent witness was perceived as less reliable and credible, although its background and witnessing conditions were identical to those of the hypothesis‐consistent witness. While this asymmetrical skepticism was not moderated by time pressure, participants under high (vs. low) time pressure were less inclined to adjust their confidence in the hypothesis in line with the witness testimony. Discussion focuses on implications for criminal investigations and theoretical contributions to investigative psychology.