A recently published study in the journal Psychological Science indicates that law enforcement officers are prone to forget events which occur after a chase or altercation with a suspect. Researchers found that officers who engaged in at least a minute of intense physical exercise shortly before an arrest remembered few details of the arrest. This finding is crucial because it is often the testimony of these officers which supports the basis of a defendant’s conviction.
“Police officers are often expected to remember in detail who said what and how many blows were received in the midst of physical struggle or shortly afterwards,” the study’s lead officer said. “The results of our tests indicate it may be very difficult for them to do this.”
The study is prompting changes at some police departments. Officers are being instructed that it is okay to admit that they do not remember the details of an encounter and that this memory lapse is not due to inattention or lack of will, but rather indicative of natural physical limitations.
“Ultimately, memory is determined by what we can process and attend to,” the lead study author said. “As exhaustion takes over, cognitive resources tend to diminish. The ability to fully shift attention is inhibited, so even potentially relevant information might not be attended to.”
The study was conducted using 52 Winnipeg police officers who were all employed for at least eight years and considered fit and healthy. The officers were briefed on three robberies and shown a picture lineup. One group of officers then rigorously used a punching bag until they were visibly tired and the other group did not. Both groups then went through a scenario involving a hostile verbal confrontation with an arrestee in a realistic home environment that included weapons.
The group of officers who underwent physical exertion before confronting the potential arrestee had vastly diminished recall capabilities in subsequent memory tests regarding the initial briefing, lineup pictures and arrest scenario. CNN reports that 90 percent of the officers who did not go through physical exertion before the arrest scenario could remember at least one detail about the arrestee whereas barely a third of the officers who used the punching bag could remember details about the arrestee.
The officers who did not undergo physical exertion before the arrest scenario were twice as likely to correctly identify the arrestee in a lineup and remembered significantly more details than the officers that underwent the punching bag exercise before the arrest.
Experts believe that this groundbreaking study will have implication in law enforcement training and criminal defense cases throughout Canada and the United States, and likely spur future research into officer memory retention.
