Criminological psychology (option): factors affecting eyewitness memory

Post-event information

Information met after an event (leading questions, other witnesses, media reports) can change memory. Loftus and Palmer (1974), the classic study, found the verb in a question ('smashed' versus 'hit') changed speed estimates and false memories of broken glass a week later. Explanations: response bias (the wording influences the answer, not the memory) or substitution / integration (the new information is merged with the original memory). This fits Bartlett's reconstructive memory (Unit 1).

Weapons focus

When a weapon is present, witnesses' attention narrows onto it, so they remember the perpetrator's face and other details less well.

• Johnson and Scott (1976): participants overheard either a calm conversation and saw a man leave with a greasy pen, or heard a violent argument and saw a man leave with a blood-stained knife. 49% correctly identified the man in the pen condition versus 33% in the knife condition.
• Loftus, Loftus and Messo (1987): eye-tracking showed participants fixated on a gun more often and for longer than on a cheque, and remembered the man less well.
• Explanations: arousal narrowing attention, or unusualness (Pickel found unusual objects such as a raw chicken had a similar effect). Field studies of real crimes often fail to find the effect, so ecological validity is questioned.

Other-race effect and stress

• Other-race (own-race) effect: people recognise faces of their own ethnic group more accurately. Meissner and Brigham (2001), a meta-analysis of 91 samples and nearly 5,000 participants, found people were about 1.4 times more likely to correctly identify an own-race face and about 1.56 times more likely to falsely identify a new other-race face. Shorter viewing time increased the bias; more interracial contact slightly reduced it. Explanation: more experience with own-race faces means better encoding of distinguishing features.
• Stress and trauma: the Yerkes-Dodson idea predicts moderate arousal helps memory but very high arousal harms it. Valentine and Mesout (2009) found visitors with high state anxiety in the London Dungeon Horror Labyrinth recalled fewer correct details and identified an actor far less accurately (17% correct above the median anxiety score versus 75% below). Some studies of real traumatic events find witnesses remember central details well, so the effect may depend on central versus peripheral detail.

Evaluation

• Laboratory studies give control and reliability but low ecological validity: participants know they are in a study, and watching a film is not being a victim.
• Ethical limits stop researchers creating real fear, which is why field settings such as the London Dungeon are valuable.
• Practical application: line-up procedures, warning juries about weapon focus and cross-race identifications, and expert testimony (Penrod and Cutler).

Worked example

Using Johnson and Scott (1976), how many percentage points lower was correct identification in the knife condition?

1. Pen condition: 49% correct.
2. Knife condition: 33% correct.
3. 49 - 33 = 16 percentage points lower, supporting weapon focus.

Answer: 16 percentage points lower.

Check yourself

1. Information from a newspaper report altering a witness's memory is an example of
   • weapons focus
   • the other-race effect
   • a self-fulfilling prophecy
   • post-event information
   Show answer

   post-event information. It comes after the event.

2. In Johnson and Scott (1976), 49% identified the man in the control condition and 33% in the weapon condition. What is the ratio of control to weapon accuracy? Give your answer to 2 decimal places.
   Show answer

   1.48. 49 / 33 = 1.48.

3. What did Loftus, Loftus and Messo (1987) measure with eye-tracking?
   • Heart rate during the film
   • Speed estimates
   • Confidence in line-up decisions
   • How often and how long participants looked at the gun
   Show answer

   How often and how long participants looked at the gun. Fixations on the weapon.

4. Pickel found a raw chicken produced effects like weapons focus. This supports which explanation?
   • Unusualness of the object captures attention
   • Arousal from threat
   • Post-event information
   • Response bias
   Show answer

   Unusualness of the object captures attention. A chicken is unusual, not threatening.

5. Meissner and Brigham (2001) found people were more likely to
   • remember other-race faces better
   • show no difference by race
   • falsely identify a new face of another race
   • only make errors with own-race faces
   Show answer

   falsely identify a new face of another race. About 1.56 times more false alarms for other-race faces.

6. The Yerkes-Dodson idea predicts that memory is best at
   • moderate arousal
   • very high arousal
   • zero arousal
   • any level, since arousal has no effect
   Show answer

   moderate arousal. An inverted U.

7. Explain one weakness of research into weapons focus.
   Show answer

   Most studies are laboratory experiments using films or staged events, so participants know it is not real and are not truly frightened, giving low ecological validity; studies of real crimes often do not find the effect.. Method plus validity problem.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification, Issue 6 (November 2024, first assessment January 2026)
• EBSCO Research Starters: Weapon focus (Johnson and Scott, 1976; Loftus, Loftus and Messo, 1987)
• NCJRS abstract: Loftus, Loftus and Messo (1987), Some facts about weapon focus, Law and Human Behavior 11(1)
• Meissner and Brigham (2001), Thirty years of investigating the own-race bias in memory for faces, Psychology, Public Policy, and Law 7
• Pearson IAL Psychology summary of studies: WPS03
• Pearson WPS03/01 examiners' report, January 2025

Last updated 8 November 2026. Spotted a mistake? Tell us.