A Meta-Analytic Review of the Effects of High Stress on Eyewitness Memory.

Abstract

In the past 30 years researchers have examined the impact of heightened stress on the fidelity of eyewitness memory. Meta-analyses were conducted on 27 independent tests of the effects of heightened stress on eyewitness identification of the perpetrator or target person and separately on 36 tests of eyewitness recall of details associated with the crime. There was considerable support for the hypothesis that high levels of stress negatively impact both types of eyewitness memory. Meta-analytic Z-scores, whether unweighted or weighted by sample size, ranged from −5.40 to −6.44 (high stress condition-low stress condition). The overall effect sizes were −.31 for both proportion of correct identifications and accuracy of eyewitness recall. Effect sizes were notably larger for target-present than for target-absent lineups, for eyewitness identification studies than for face recognition studies and for eyewitness studies employing a staged crime than for eyewitness studies employing other means to induce stress.

Impact of disguise on identification decisions and confidence with simultaneous and sequential lineups.

“…Witnesses may interpret a disguised perpetrator as more dangerous, and this perception may increase cognitive load. As a result, witnesses may have fewer processing resources available for encoding (Deffenbacher, Bornstein, Penrod, & McGorty, 2004). Similarly, type of disguise may influence how the target's intentions are perceived (i.e., if someone looks like a "criminal" or not), and thus influence encoding strategies.…”

The Impact of Testing on the Formation of Children's and Adults' False Memories

“…Naturally, because of ethical constraints and the age of our youngest participants, we were not able to show a highly upsetting video. It is known that stress, which is likely experienced during a real crime, can negatively influence memory (Deffenbacher, Bornstein, Penrod, & Kieman, 2004). However, others argue that the impact might be neutral (e.g., Krix et al, 2016; Sauerland et al, 2016) or even positive (e.g., Roozendaal & McGaugh, 2011).…”

Why eyewitnesses fail

“…Three decades of such studies have quantified the effects of many of these variables on identification accuracy (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Simply put, data on estimator variables tell us something about the probative value of eyewitness testimony-and thus the degree to which law enforcement and the courts should be circumspect-given the conditions under which a crime was witnessed.…”