Accuracy of eyewitness memory for persons encountered during exposure to highly intense stress
Introduction
Over the past 20 years there have been over 2000 scientific investigations on the reliability of eyewitness identification (Cutler & Penrod, 1995). The majority of studies have been conducted in the laboratory using videotapes or live simulations of crime events; only a handful have been field studies involving victims and eyewitnesses of real crimes. Laboratory studies are limited because crime simulations do not entail the degree of personal “threat” or “alarm” that an individual may experience during actual life-threatening events (Penrod et al., 1995). A major limitation of extant field studies is the inability to control for specific factors (such as severity and intensity of traumatic events) that may significantly affect human memory. Limitations notwithstanding, the relevant literature supports the general view that memory formation is better in response to events that are perceived to be as stressful, personally relevant, and that elicit adequate physiological arousal or alarm Gold, 1992, Canli et al., 2000. At apparent odds with this general consensus are the findings from recent studies suggesting that the eyewitness memories reported by combat veterans who have been exposed to life-threatening events during combat may be inconsistent and subject to substantial error Southwick et al., 1997, Roemer et al., 1998. In order to explain this phenomenon, some have proposed that during exposure to potentially traumatic events, peritraumatic symptoms of dissociation may disrupt the encoding of memory and contribute errors in memory for the traumatic events (Koopman et al., 1994).
The current limitations in eyewitness studies and the difficulties in applying such data to studies of memories in people exposed to traumatic stress could be effectively overcome by evaluating human memory at a venue where subjects are exposed to valid, reliable, and controlled conditions of realistic stress. Recent evidence suggests that military survival school training may provide such a venue. A series of psychobiological investigations conducted by our laboratory at the U.S. Army survival school training program have shown that survival school represents a valid and reliable model for the study of realistic, threat-to-life stress in humans Morgan, 2000, Morgan et al., 2000, Morgan et al., 2000, Morgan et al., 2001, Morgan et al., 2001. Unlike mock crime or field studies, survival school investigations can apply severe stress in a uniform manner that controls for intensity and duration across subjects. The extreme stress experienced by participants is pronounced and results in significant alterations of neurobiological processes and psychological experiences (such as peritraumatic dissociation) that are on a par with those noted in individuals experiencing real-world, threat-to-life events such as landing on an aircraft carrier at night for the first time, skydiving for the first time, open-heart surgery, and actual combat Morgan et al., 2000, Morgan et al., 2001. As such, the survival school is an ideal “laboratory” for prospective, objective evaluation assessing the accuracy of eyewitness memory for events experienced during exposure to realistic stress.
Survival school training is divided into two general phases. The first phase is didactic; the second phase is experiential. In the didactic phase, participants undergo one week of classroom instruction to prepare them for the experiential phase. In the experiential phase, participants are confined in a mock prisoner of war camp (POWC). This phase is designed to offer one of the most challenging training experiences that active duty participants will ever experience while in the military. In the POWC, each participant is placed in isolation and then subjected to various types of interrogation. These interrogations are designed to test the limits and abilities of the participants to withstand “exploitation by the enemy” and to demonstrate problem-solving skills while experiencing extreme stress. As documented in our previous investigations, all school participants are exposed to both high- and low-intensity types of interrogation stress.
As we have previously reported, the stress experienced during the confinement phase is intense and provides a valid environment for the study of uncontrollable stress in human subjects. Psychological symptoms of peritraumatic dissociation, and stress hormones (such as cortisol, norepinephrine, and epinephrine), are significantly elevated and comparable to alterations documented in real-world, threat-to-life events, whereas gonadal steroids, such as testosterone, are reduced below fertility levels in response to TL stress Morgan et al., 2000, Morgan et al., 2001, Morgan et al., 2001. These two types of interrogations experienced by participants differ in the degree to which the participant is confronted with the threat of physical violence during the interrogation. Thus, survival school offers a model wherein there is (1) exposure to realistic, personally relevant acute stress; (2) uniform application of stressors (high and low) across subjects; (3) objective data about the “perpetrator” (interrogator) against which eyewitness reports provided by subjects can be compared; and finally, (4) a uniform time frame for the poststress assessment of memory for perceived events.
In the present study, accuracy of suspect recognition after high-stress and low-stress interrogation was assessed. Although some investigators have evaluated eyewitness memory in subjects who have personal, compared to vicarious, exposure to stress Lindberg et al., 2001, Yuille et al., 1994, there do not appear to be any empirical studies that have critically evaluated the relationship between realistic high-intensity stress and the accuracy of eyewitness recognition. In a study comparing the eyewitness testimonies of children who directly versus indirectly experienced a painful medical inoculation, Lindberg, Jones, McComas Collard, and Thomas (2001) reported that those with direct and personal experience exhibited increased production of flashbulb-like memories (Lindberg et al., 2001). Similarly, Yuille et al. (1994) reported that adult police trainees who directly participated in stressful role plays exhibited increased accuracy of eyewitness memory and resistance to decay over time compared to fellow trainees who simply observed the role plays (Yuille et al., 1994). Although the data from these investigations support the idea that eyewitness memory is better if the stress has personal relevance, the intensity of the stress experienced by subjects was not of a magnitude such as that experienced by victims of trauma. As such, the data from these studies may not be applicable to understanding the nature of memory for traumatic events. Because preclinical (Haycock et al., 1977) and human neurobiological experiments (O'Carrol et al., 1999) have shown that increased levels of arousal and adrenalin may enhance memory, we hypothesized that eyewitness accuracy rates would be higher for the high-stress interrogation compared to low-stress interrogation.
We also compared accuracy of eyewitness recognition using three established law-enforcement methods for identifying crime suspects: the live lineup, the photo-spread technique, and the sequential photo method. Based on previous literature and the Department of Justice (DOJ) guidelines (The Guide, US DOJ, 2003), we hypothesized that accuracy rates of suspect recognition would be higher when using the sequential, compared to the live lineup and photo-spread techniques. Finally, we assessed differences in accuracy in eyewitness identification for cued and uncued photographs of suspects presented during the sequential photo method. Because studies in humans have shown that memory may be facilitated by contextual cues, we hypothesized that accuracy of suspect recognition would be better for cued, compared to uncued, photographs.
Section snippets
Subjects
Five hundred and nine of 530 consecutively recruited, active-duty military personnel enrolled in military survival school training were the subjects of this investigation. The mean age of subjects was 25 (S.D.=5). The average number of years in the service was 4.2 (S.D.=4). As designated by their military branch, 255 (50%) were navy air wing personnel, and 163 (32%) were marine pilots. Ninety-two (18%) subjects were sailors.
The assignment of subjects to a survival school cohort was determined
Results
As shown in Table 1, regardless of method of assessment, the accuracy of eyewitness recognition (true positive responses) for the interrogator appeared to be greater for the low-, compared to the high-stress condition. This observation was statistically significant as indicated by nonparametric, within-subject comparisons (sign tests) for the subjects who participated in the live lineup and photo-spread methods of testing (Studies 1 and 2) and by chi-square comparisons between the subjects who
Discussion
Contrary to the popular conception that most people would never forget the face of a clearly seen individual who had physically confronted them and threatened them for more than 30 min, a large number of subjects in this study were unable to correctly identify their perpetrator. These data provide robust evidence that eyewitness memory for persons encountered during events that are personally relevant, highly stressful, and realistic in nature may be subject to substantial error.
Within-subject
Acknowledgements
The authors thank CDR Doherty, CDR Fred Rusinski, CDR Kyle Craigie, Stephen Garrett, PA, CPO John Burkhart, PO1 Gary Johnson, Jeremy Cordova, MA, and Willie Ford. Their support and work significantly facilitated the completion of this project. Funding for this project was provided by a grant from the Center for Naval Analyses (CAM) and from the USARIEM (CAM).
The opinions reflected in this paper are not to be considered policy or guidance of the U.S. Navy or Army, or the Department of Defense,
References (36)
- et al.
Facilitation of time-dependent memory processes with posttrial epinephrine injections
Behavioral Biology
(1975) - et al.
Enhancement of retention with centrally administered catecholamines
Experimental Neurology
(1977) - et al.
Peripheral epinephrine modulates the effects of post-training amygdala stimulation on memory
Behavioral Brain Research
(1985) - et al.
Hormone profiles in humans experiencing military survival training
Biological Psychiatry
(2000) - et al.
Plasma neuropeptide-Y in humans exposed to military survival training
Biological Psychiatry
(2000) - et al.
Epinephrine-induced memory facilitation: Attenuation by adrenoceptor antagonists
European Journal of Pharmacology
(1986) - et al.
The amygdala's role in long-term declarative memory for gist and detail
Behavioral Neurosciences
(2001) - et al.
Measurement of dissociative states with the Clinician-Administered Dissociative States Scale (CADSS)
Journal of Traumatic Stress
(1998) - et al.
Event-related activation in the human amygdala associates with later memory for individual emotional experience
Journal of Neuroscience
(2000) - et al.
Mistaken identification: The eyewitness, psychology and the law
(1995)
Enhancing enhanced eyewitness memory: Refining the cognitive interview
Journal of Police Science and Administration
Reinstatement of context following exposure to post-event information
British Journal of Psychology
Modulation of memory processing: Enhancement of memory in rodents and humans
Stress regulation of memory processes: Role of peripheral catecholamines and glucose
Frequency of eyewitness identification in criminal cases: A survey of prosecutors
Bulletin of the Psychonomic Society
Stress and treatment induced elevations of cortisol levels associated with impaired declarative memory in healthy adults
Life Sciences
Predictors of post traumatic stress symptoms among survivors of the Oakland/Berkeley California, firestorm
American Journal of Psychiatry
Cited by (174)
Facing stress: No effect of acute stress at encoding or retrieval on face recognition memory
2021, Acta PsychologicaNorepinephrine and glucocorticoid effects on the brain mechanisms underlying memory accuracy and generalization
2020, Molecular and Cellular NeuroscienceTraumatised Witnesses in International Criminal Trials: Testimony, Fair Proceedings, and Accurate Fact-Finding
2024, Traumatised Witnesses in International Criminal Trials: Testimony, Fair Proceedings, and Accurate Fact-FindingThe role of suspect development practices in eyewitness identification accuracy and racial disparities in wrongful conviction
2024, Social Issues and Policy ReviewExamining the effects of negative emotion and interviewing procedure on eyewitness recall
2023, Applied Cognitive PsychologyProfessional Judgment for Lawyers
2023, Professional Judgment for Lawyers