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[ ... ]"The legal system puts a great deal of emphasis on witness accounts, particularly those of professional witnesses like police officers. Investigators and courts need to understand that an officer who cannot provide details about an encounter where physical exertion has played a role is not necessarily being deceptive or uncooperative. An officer's memory errors or omissions after an intense physical struggle should not unjustly affect his or her credibility."

[ ... ]

Half of the officers then engaged in a full-force physical attack on a 300lb hanging water bag and the others (a control group) were assigned as observers. Officers selected their own "assault movements" on the bag attack — punches, kicks, and/or palm, elbow, and knee strikes—and were verbally encouraged by a trainer during the task. They continued the assault on the bag until they no longer had strength to keep going or until they were breathless and struggling to continue.

After a short delay, the "target individual" emerged from another room and shouted aggressively at the officer to get out of his property. The individual was not armed, but several of the weapons were within easy reach.

Dr Hope found those who had been asked to exert themselves physically remembered less about the target individual and made more recall errors compared to the control group of observers. The officers who had been exerted also recalled less about the initial briefing information and what they did report was less accurate. Officers who had been exerted also reported less about an individual they encountered incidentally while en route to the trailer. While more than 90 per cent of non-exerted observers were able to recall at least one descriptive item about him, barely one-third of exerted officers remembered seeing him at all.

Everyone remembered seeing the angry suspect in the trailer, but non-exerted observers provided a significantly more detailed description of him and made half as many errors in recall as those who were exhausted. These observers were also twice as likely to correctly identify the suspect from a line-up.
For a copy of the article "Witnesses in Action: The Effect of Physical Exertion on Recall and Recognition" and access to other Psychological Science research findings, please contact Lucy Hyde at 202-293-9300 or