- Published: September 5, 2012
- Written by Joshua Jackson
When considering the value and use of eyewitness testimony it is appropriate to take into account not just the normal difficulties and failings of human memory and recall but also the additional issues that come with incidents of crime such as unexpected and stressful conditions. As one review states, “when witnessing a crime of violence, the response of the eyewitness is almost always one of generating a stress response to the stressor imposed by the crime.” (Deffenbacher 2004) To evaluate the significance of this stress response we must investigate the relationship between stress and memory.
In a 1977 paper, Harvard researchers Roger Brown and James Kulik identified a special case of autobiographical memory known as Flashbulb memories. These are described as “memories for the circumstances in which one first learned of a very surprising and consequential (or emotionally arousing) event.” (Brown 1977) In the case of flashbulb memories, subjects are found to give vivid detailed descriptions of the time of the memory. These descriptions were initially taken as evidence that the brain retained accurate information of these events long-term.
However, a study conducted at Duke University beginning September 12th, 2001 showed that the consistency of flashbulb memories degraded similarly to everyday memories while participant's “belief in the accuracy of memory declined only for everyday memories.” (Talarico 2003) This effect might lead to a significant source of error in the justice system if the testimony of a witness is weighed according to the witnesses' own certainty and the vividness and detail of their account of the experience.
Recent research appears to be edging toward an understanding of the conditions leading to these effects. A 2002 review in Nature Neuroscience describes a model whereby “alterations in hippocampal functioning after stress are due to excessive activity exerted by the amygdala on the hippocampus.” (Kim 2002) These alterations in hippocampal functioning lead to an impairment of hippocampus-dependent memory, including the types of information that would come up in a court room. However, the article itself describes the model as “simple”.
1. Kenneth A. Deffenbacher, Brian H. Bornstein, Steven D. Penrod and E. Kiernan McGorty, A Meta-Analytic Review of the Effects of High Stress on Eyewitness Memory , Law and Human Behavior Vol. 28, No. 6 (Dec., 2004), pp. 687-706
2. Roger Brown, James Kulik, Flashbulb memories, Cognition, Volume 5 Issue 1 (1977), pp. 73-99
3. Talarico JM, Rubin DC, Confidence, not consistency, characterizes flashbulb memories. Psychol Sci. 2003 Sep;14(5) pp. 455-61
4. Kim JJ, Diamond DM, The stressed hippocampus, synaptic plasticity and lost memories, Nat Rev Neurosci. 2002 Jun;3(6), pp. 453-62