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Criminal Justice, Human Rights

Witnesses in action: The effect of physical exertion on recall and recognition

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The justice system relies upon eyewitness reports from law enforcement or citizens to prosecute and sentence criminal suspects, but faulty eyewitness identification is a common reason for a subsequent exoneration. Research on physical exertion’s impact on memory suggest that while low-level activity can facilitate remembering, higher levels may generate more “neural noise” in the brain and interfere with the memory process.

A 2012 study published in Psychological Science, “Witnesses in Action: The Effect of Physical Exertion on Recall and Recognition,” describes an experiment designed to measure the impact of physical exertion on memory and cognition. Twenty-four pairs of Canadian metropolitan law enforcement professionals were briefed on a series of recent armed robberies. In each pair, one officer (Officer A) exercised intensely and one officer didn’t (Officer B). The pair was directed to the residence of the primary suspect (the “critical target”). In each instance, an actor playing the critical target shouted at Officer A to leave his house; the encounter was repeated separately with Officer B. After a short delay, both officers answered questions about the briefing and reported details about the possible subject (“incidental target”), the known suspect (“the critical target”) and the scenario. Officers were finally shown a photographic lineup of possible suspects, including one of the critical target/actor, and asked to identify him.

Findings of the report include that:

  • “Participants in the exertion condition made fewer correct responses to cued recall questions concerning the original briefing than did participants in the no-exertion condition.” The authors suggest that the memory consolidation process may have been somehow interrupted by the period of intense exertion in the middle of the experiment.
  • When asked about the details of the briefing, 84% of the Officer B participants provided correct information, compared with only 52% of Officer A participants. “Participants in the exertion condition also provided fewer correct update details … than did control participants.”
  • Officer A participants were able to identify the critical target from a lineup 27% of the time, while Officer B participants were able to correctly identify him 54% of the time. Additionally, 27% of Officer A participants reported that the target was definitely not in the lineup, compared with only 8% of Officer B participants.
  • “There was no difference between conditions in the detection of weapons or in the number of weapons reported [at the scene], which suggests that attentional resources may have been diverted to risk-assessment activities rather than the encoding of the critical target.”

The authors note the importance of eyewitness testimony in judicial proceedings and suggest that the study’s findings speak to “a more generalized impairment” of memory. “The delivery of justice may depend on the statements and identifications provided by witnesses who have experienced physical exertion, either in the course of their occupational duties or due to the nature of the crime perpetrated against them. Such witnesses may be required to justify or rationalize deficits or inconsistencies in their accounts.”

Tags: cognition, crime, guns

    Writer: | Last updated: March 28, 2012

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    Media analysis

    Read the study-related Gizmodo blog post titled "Being Chased By the Fuzz? Leg-It Because They Might Not Actually Remember Who You Are."

    1. Reporter's use of the study: Evaluate what the reporter chose to include and exclude from the study. Would the audience have acquired a clear understanding of the study's findings and limits from this article?
    2. Reporter's use of other material: Assess the material in the article that is not derived from the study. For example: Does the reporter place the study in the context of other research and to what effect? Does the reporter include reactions to the study from other researchers or interested parties (e.g., political groups, business leaders, or community members) and are their credentials or possible biases made clear?

    Study analysis

    Read the full study titled "Witnesses in Action: The Effect of Physical Exertion on Recall and Recognition."

    1. What are the study's key technical term(s)? Which ones need to be put into language a lay audience can understand?
    2. Do the study’s authors put the research into context and show how they are advancing the state of knowledge about the subject? If so, what did the previous research indicate?
    3. What is the study’s research method? If there are statistical results, how did the scholars arrive at them?
    4. Evaluate the study's limitations. (For example, are there weaknesses in the study's data or research design?)
    5. How could the findings be misreported or misinterpreted by a reporter? In other words, what are the difficulties in conveying the data accurately? Give an example of a faulty headline or story lead.

    Newswriting and digital reporting assignments

    1. Write a lead, headline or nut graph based on the study.
    2. Spend 60 minutes exploring the issue by accessing sources of information other than the study. Write a lead (or headline or nut graph) based on the study but informed by the new information. Does the new information significantly change what one would write based on the study alone?
    3. Compose two Twitter messages of 140 characters or fewer accurately conveying the study’s findings to a general audience. Make sure to use appropriate hashtags.
    4. Choose several key quotations from the study and show how they would be set up and used in a brief blog post.
    5. Map out the structure for a 60-second video segment about the study. What combination of study findings and visual aids could be used?
    6. Find pictures and graphics that might run with a story about the study. If appropriate, also find two related videos to embed in an online posting. Be sure to evaluate the credibility and appropriateness of any materials you would aggregate and repurpose.

    Class discussion questions

    1. What is the study’s most important finding?
    2. Would members of the public intuitively understand the study’s findings? If not, what would be the most effective way to relate them?
    3. What kinds of knowledgeable sources you would interview to report the study in context?
    4. How could the study be “localized” and shown to have community implications?
    5. How might the study be explained through the stories of representative individuals? What kinds of people might a reporter feature to make such a story about the study come alive?
    6. What sorts of stories might be generated out of secondary information or ideas discussed in the study?