The Interdependence of Perceived Confession Voluntariness and Case Evidence

The current research investigated the mechanisms by which perceptions of confession evidence both influence and are influenced by perceptions of other case evidence using the theoretical framework of coherence-based reasoning (CBR). CBR posits that ambiguity and uncertainty are eschewed by artificially imposing consistency between pieces of evidence through bidirectional reasoning: Inferences about evidence lead to a preferred verdict, which in turn radiates backward to influence the perception of evidence. Two studies tested the CBR account with regard to confessions. An online sample of participants evaluated confession and nonconfession evidence at pretest and posttest. Study 1 revealed that, during pretest, participants (N = 119) deemed the evidence independent and nonprobative and the confession to be voluntary. However, at posttest, in the context of a criminal trial, participants considered the same evidence interrelated and highly inculpatory or exculpatory, depending on their verdict. Moreover, participants who voted to convict deemed the confession substantially voluntary, whereas participants who voted to acquit deemed it involuntary. Study 2 experimentally manipulated the strength of the nonconfession evidence in an effort to push participants (N = 127) toward a particular verdict. The same patterns of results emerged but were conditional on the strength of the nonconfession evidence: Strong case evidence caused the confession to be perceived as more voluntary, despite the fact that the confession was held constant. These findings replicate the coherence effect in a new domain and suggest that judges conducting harmless error analysis or making admissibility decisions might underappreciate the impact of confession evidence on jurors' verdicts.