Estimating the impact of estimator variables on eyewitness identification: A fruitful marriage of practical problem solving and psychological theorizing

Abstract

The trier of fact has the practical problem of trying to estimate the impact of several estimator variables on the reliability of an eyewitness's identification. Until relatively recently, psychologists were either unsure as to the direction and magnitude of effect on eyewitness memory of certain estimator variables (e.g. heightened stress) or could offer the trier of fact only vague empirical generalizations (e.g. forgetting increases over time, most rapidly at first). At present, however, a number of meta-analytic reviews of the effects of certain estimator variables have accumulated, as have a number of theoretical analyses of their operation in the eyewitness identification context, theoretical treatments resulting from fruitful application of theories from cognitive psychology and behavioural neuroscience. The combined accumulations are now sufficient to constitute a 'critical mass' of knowledge, thereby permitting the trier of fact to gain more precise information regarding the impact of these estimator variables on the fidelity of eyewitness report.A century ago, there appeared a slim, but controversial volume of essays, On the Witness Stand (Münsterberg, 1908), in which the author claimed that applied psychology could make substantial contributions to the improved operation of the courts and criminal justice system, contributions yielding improvements in the quality of justice. Münsterberg's claim was a bold one, inasmuch as any of the data from experimental psychology laboratories that he wished to apply to the intersection of psychology and criminal justice were at most a quarter of a century old, much of the data having been generated in studies of sensory psychology and perception. Nevertheless, Münsterberg clearly stated his belief that experimental psychology had had sufficient time to develop a solid foundation of knowledge, a foundation sufficient for an applied psychology to grow and prosper. On the other hand, the data generated by applied psychology studies, seemingly more directly relevant to his claim that psychology could assist the law, were even more sparse than that coming from basic research laboratories. After all, research pertaining to the psychology of testimony had been underway for little more than 5 years, having begun with the publication of the monograph La Suggestibilité (Binet, 1900). APPLIED COGNITIVE PSYCHOLOGY Appl. Cognit. Psychol. 22: 815-826 (2008) Published online in Wiley InterScience (www.interscience.wiley.com)

The role of estimator variables in eyewitness identification.

“…Instead, the argument has been made that under suboptimal conditions of encoding and retrieval, the trustworthiness of eyewitness identifications can be expected to decrease. For example, Deffenbacher (2008) argued that under poor information processing conditions, "…not only will familiar faces be judged to be unfamiliar and unfamiliar faces be judged as familiar more frequently, but the same confidence rating is also more likely to be applied both to a judgment that a face seen before is indeed familiar and to a judgment that another face, never seen before, is also familiar" (p. 819).…”

14. Psychology and criminal justice

“…One distinction that was drawn by Wells in 1978 has been revisited several times by other authors and was eventually helpful in moving the debate forward and in providing useful information for the courts (Deffenbacher, 2008). Wells highlighted the importance of considering estimator and system variables separately.…”

Lessons from the origins of eyewitness testimony research in Europe

“…The arousal and stress likely to be present in real cases cannot be approached in the laboratory for obvious legal and ethical reasons. As a consequence, we need more studies that push the experimental paradigms to the limits, collecting physiological measures to link arousal to perceptual and memory measures (see Deffenbacher, 2008). We also need more large-scale archival studies in which numerous independent/predictor variables are coded to assess their impact on recall and identification.…”

“…Besides theoretically driven narrative reviews, such an integration can be achieved by quantitative synthesis, that is, metaanalysis (see also Deffenbacher, 2008). Via meta-analyses, the relative importance of different determinants of eyewitness behaviour can be assessed by comparing their effect sizes.…”

“…For example, in order to narrow the number of potential suspects, police routinely collect some form of person description, or construct a (computer) facial composite, shortly after the crime to find potential suspects. Identification procedures, on the other hand, are seldom conducted at the first interrogation but usually much later, at least a day, a week, or even months after the original testimony (see also Deffenbacher, 2008).…”