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Allegiance Bias in Statement Reliability Evaluations Is Not Eliminated by Falsification Instructions

Published Online:https://doi.org/10.1027/2151-2604/a000416

Abstract. Are expert witnesses biased by the side (defense vs. prosecution) that hires them? We examined this issue by having students act as expert witnesses in evaluating interviews in a child sexual abuse case (Experiment 1, N = 143) and tested the value of an instruction to counteract such allegiance effects. The intervention concerned an instruction to consider arguments both for and against the given hypothesis (i.e., two-sided instructions; Experiment 2, N = 139). In Experiment 3 (N = 123), we additionally provided participants with three different scenarios. Participants received a case file regarding a case of alleged sexual abuse. With the file, participants received an appointment letter emphasizing elements of the file that questioned (defense) or supported (prosecution) the veracity of the accusation. Participants displayed allegiance bias (Experiments 1–3), but two-sided instructions were not successful in eliminating allegiance bias (Experiments 2 and 3). The findings underscore the importance of legal safeguards in expert witness work.

References

  • Arkes, H. R. (1991). Costs and benefits of judgment errors: Implications for debiasing. Psychological Bulletin, 110, 486–498. https://doi.org/10.1037/0033-2909.110.3.486 First citation in articleCrossrefGoogle Scholar

  • Ask, K., & Granhag, P. A. (2005). Motivational sources of confirmation bias in criminal investigations: The need for cognitive closure. Journal of Investigative Psychology and Offender Profiling, 2, 43–63. https://doi.org/10.1002/jip.19 First citation in articleCrossrefGoogle Scholar

  • Ask, K., & Granhag, P. A. (2007). Motivational bias in criminal investigators’ judgments of witness reliability. Journal of Applied Social Psychology, 37, 561–591. https://doi.org/10.1111/j.1559-1816.2007.00175.x First citation in articleCrossrefGoogle Scholar

  • Beckham, J. C., Annis, L. V., & Gustafson, D. J. (1989). Decision making and examiner bias in forensic expert recommendations for not guilty by reason of insanity. Law & Human Behavior, 13, 79–87. https://doi.org/10.1007/BF01056164 First citation in articleCrossrefGoogle Scholar

  • Edens, J. F., Cox, J., Smith, S. T., DeMatteo, D., & Sörman, K. (2015). How reliable are Psychopathy Checklist – Revised scores in Canadian criminal trials? A case law review. Psychological Assessment, 27, 447–456. https://doi.org/10.1037/pas0000048 First citation in articleCrossrefGoogle Scholar

  • Faul, F., Erdfelder, E., Lang, A. G., & Buchner, A. (2009). Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses. Behavior Research Methods, 41, 1149–1160. https://doi.org/10.3758/BRM.41.4.1149 First citation in articleCrossrefGoogle Scholar

  • Festinger, L. (1957). A theory of cognitive dissonance. Stanford, CA: Stanford University Press. First citation in articleCrossrefGoogle Scholar

  • Guarnera, L. A., Murrie, D. C., & Boccaccini, M. T. (2017). Why do forensic experts disagree? Sources of unreliability and bias in forensic psychology evaluations. Translational Issues in Psychological Science, 3, 143–152. https://doi.org/10.1037/tps0000114 First citation in articleCrossrefGoogle Scholar

  • Lord, C. G., Lepper, M. R., & Preston, E. (1984). Considering the opposite: A corrective strategy for social judgment. Journal of Personality & Social Psychology, 47, 1231–1243. https://doi.org/10.1037/0022-3514.47.6.1231s First citation in articleCrossrefGoogle Scholar

  • Lloyd, C. D., Clark, H. J., & Forth, A. E. (2010). Psychopathy, expert testimony, and indeterminate sentences: Exploring the relationship between Psychopathy Checklist-Revised testimony and trial outcome in Canada. Legal and Criminological Psychology, 15, 323–339. https://doi.org/10.1348/135532509X468432 First citation in articleCrossrefGoogle Scholar

  • Marksteiner, T., Ask, K., Reinhard, M. A., & Granhag, P. A. (2011). Asymmetrical scepticism towards criminal evidence: The role of goal‐and belief‐consistency. Applied Cognitive Psychology, 25, 541–547. https://doi.org/10.1002/acp.1719 First citation in articleCrossrefGoogle Scholar

  • McAuliff, B. D., & Arter, J. L. (2016). Adversarial allegiance: The devil is in the evidence details, not just on the witness stand. Law and Human Behavior, 40, 524–535. https://doi.org/10.1037/lhb0000198 First citation in articleCrossrefGoogle Scholar

  • Murrie, D. C., Boccaccini, M. T., Guarnera, L. A., & Rufino, K. A. (2013). Are forensic experts biased by the side that retained them? Psychological Science, 24, 1889–1897. https://doi.org/10.1177/0956797613481812 First citation in articleCrossrefGoogle Scholar

  • Murrie, D. C., Boccaccini, M. T., Turner, D. B., Meeks, M., Woods, C., & Tussey, C. (2009). Rater(dis)agreement on risk assessment measures in sexually violent predator proceedings: Evidence of adversarial allegiance in forensic evaluation? Psychology, Public Policy, & Law, 15, 19–53. https://doi.org/10.1037/a0014897 First citation in articleCrossrefGoogle Scholar

  • O’Brien, B. (2009). Prime suspect: An examination of factors that aggravate and counteract confirmation bias in criminal investigations. Psychology, Public Policy, and Law, 15, 315–334. https://doi.org/10.1037/a0017881 First citation in articleCrossrefGoogle Scholar

  • Otto, R. K. (1989). Bias and expert testimony of mental health professionals in adversarial proceedings: A preliminary investigation. Behavioral Sciences & the Law, 7, 267–273. https://doi.org/10.1002/bsl.2370070210 First citation in articleCrossrefGoogle Scholar

  • Popper, K. R. (1959). The logic of scientific discovery. Abingdon-on-Thames, UK: Routledge. First citation in articleGoogle Scholar

  • Rassin, E. (2018). Reducing tunnel vision with a pen‐and‐paper tool for the weighting of criminal evidence. Journal of Investigative Psychology and Offender Profiling, 15, 227–233. https://doi.org/10.1002/jip.1504 First citation in articleCrossrefGoogle Scholar

  • Reese, E. J. (2012). Techniques for mitigating cognitive biases in fingerprint identification. UCLA Law Review, 59, 1252–1290. First citation in articleGoogle Scholar

  • Sanna, L. J., Schwarz, N., & Stocker, S. L. (2002). When debiasing backfires: Accessible content and accessibility experiences in debiasing hindsight. Journal of Experimental Psychology: Learning, Memory, and Cognition, 28, 497–502. https://doi.org/10.1037/0278-7393.28.3.497 First citation in articleCrossrefGoogle Scholar

  • Sauerland, M., & Otgaar, H. (2020). Teaching psychology students to change (or correct) controversial beliefs about memory works. Manuscript in preparation. First citation in articleGoogle Scholar

  • Slovic, P., & Fischhoff, B. (1977). On the psychology of experimental surprises. Journal of Experimental Psychology: Human Perception and Performance, 3, 544–551. https://doi.org/10.1037/0096-1523.3.4.544 First citation in articleCrossrefGoogle Scholar

  • Van Koppen, P. J., & Mackor, A. R. (2019). A scenario approach to the Simonshaven case. Topics in Cognitive Science. Advance online publication. https://doi.org/10.1111/tops.12429 First citation in articleGoogle Scholar

  • Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12, 129–140. https://doi.org/10.1080/17470216008416717 First citation in articleCrossrefGoogle Scholar