Serial effects of evidence on legal decision-making

Abstract

The order in which evidence is presented to a criminal court might influence the verdict. This study investigated the serial position effect in a judicial context. 1831 Swiss criminal judges received a filmed mock trial with a specific order stemming from the combination of 3 witnesses: a forensic expert, an eyewitness and an alibi witness. The evidence order was completely counterbalanced and each witness represented a different type of testimony chosen in accordance with the legal practice. If judges rendered their verdict on the basis of the first witness, a primacy effect would be observed. Conversely, if the last testimony would be preponderant, a recency effect would influence their judgment. Results showed a recency effect based on a defence eyewitness whose placement in the last position provoked significantly less condemnations. Furthermore, the probative value estimated by the judges for each piece of evidence was not associated with its serial impact. Results are discussed in relation to legal decision-making and the identification of a central witness mediating order effects.

Resumen

The order in which evidence is presented to a criminal court might influence the verdict. This study investigated the serial position effect in a judicial context. 1831 Swiss criminal judges received a filmed mock trial with a specific order stemming from the combination of 3 witnesses: a forensic expert, an eyewitness and an alibi witness. The evidence order was completely counterbalanced and each witness represented a different type of testimony chosen in accordance with the legal practice. If judges rendered their verdict on the basis of the first witness, a primacy effect would be observed. Conversely, if the last testimony would be preponderant, a recency effect would influence their judgment. Results showed a recency effect based on a defence eyewitness whose placement in the last position provoked significantly less condemnations. Furthermore, the probative value estimated by the judges for each piece of evidence was not associated with its serial impact. Results are discussed in relation to legal decision-making and the identification of a central witness mediating order effects.

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