Eyewitness Testimony

Eyewitness testimony (EWT) is the evidence provided by a person who witnessed a crime or significant event. It is one of the most important — and most controversial — types of evidence in the criminal justice system. Psychological research has shown that EWT can be surprisingly unreliable, yet juries tend to find it very persuasive.

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What is Eyewitness Testimony?

EWT refers to an account given by a person who has witnessed a crime or event. It typically includes:

• Recall of events — what happened, in what order
• Description of people — what the suspect looked like, what they were wearing
• Identification — picking out a suspect from a line-up or set of photographs

EWT is important because it is often the only evidence available in criminal cases. However, research has consistently shown that eyewitness accounts are not always accurate and can be influenced by a range of psychological factors.

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Loftus and Palmer (1974): The Leading Questions Study

This study (described in the previous lesson) demonstrated that the wording of questions asked after an event can significantly alter a person's memory of that event.

Key findings recap:

• The verb used to describe a car crash ("smashed" vs "contacted") affected speed estimates
• One week later, those in the "smashed" condition were more likely to falsely report seeing broken glass
• This suggests that post-event information can be integrated into the original memory, creating a distorted or false memory

Implications

Loftus and Palmer's findings suggest that:

1. Police officers must be very careful about how they word questions during interviews
2. Lawyers in court can influence a witness's testimony through carefully chosen questions
3. Memory for an event is not fixed — it can be altered after the event by the way questions are framed

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Factors Affecting the Reliability of EWT

flowchart TD
    A[EWT Reliability] --> B[Anxiety]
    A --> C[Leading Questions]
    A --> D[Post-Event Discussion]
    A --> E[Time Delay]
    A --> F[Confidence]
    B --> B1["Weapon focus<br/>narrows attention"]
    C --> C1["Loftus and Palmer<br/>distort memory"]
    D --> D1["Memory contamination<br/>between witnesses"]
    E --> E1["Decay and<br/>interference"]
    F --> F1["Weak link to<br/>actual accuracy"]

1. Anxiety

The effects of anxiety on EWT are debated:

• Weapon focus effect (Johnson and Scott, 1976) — anxiety caused by a weapon narrows attention to the weapon, reducing accuracy of identification of the person holding it
• Yuille and Cutshall (1986) studied witnesses to a real shooting and found that those who reported higher levels of stress actually gave more accurate accounts, even after 5 months — this contradicts findings from lab studies and suggests that moderate real-life anxiety may actually enhance memory for central details

2. Leading Questions

As Loftus and Palmer demonstrated, the way questions are phrased can alter memories. Leading questions suggest a particular answer and can distort the witness's recall.

3. Post-Event Discussion

When witnesses discuss an event with each other or are exposed to media reports, their memories can become contaminated with details they did not personally witness.

4. Time Delay

The longer the delay between an event and recall, the less accurate the memory is likely to be. This is due to decay (memories fading over time) and interference (new experiences disrupting old memories).

5. Confidence

Research has shown that there is often a weak relationship between how confident a witness is and how accurate their testimony actually is. A witness can be very confident but completely wrong, and juries may be misled by a confident witness.

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The Importance of EWT in the Justice System

EWT has been responsible for both convictions and wrongful convictions:

• The Innocence Project (a US organisation that uses DNA evidence to overturn wrongful convictions) has found that mistaken eyewitness identification is the leading cause of wrongful convictions — it contributes to approximately 70% of overturned convictions
• This highlights the urgent need for better interviewing techniques and for courts to treat EWT with caution

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Evaluation of Research into EWT

Strengths

• Research by Loftus and Palmer has had a significant real-world impact, leading to changes in police interview procedures
• Studies such as Yuille and Cutshall (1986) have examined EWT in real-life settings, increasing ecological validity
• The findings have important practical applications for the criminal justice system

Weaknesses

• Many studies of EWT use artificial settings (lab experiments with video clips rather than real crimes), reducing ecological validity
• Participants in lab studies know they are not real witnesses and may not experience the same emotional reactions as real witnesses
• Demand characteristics — participants may change their answers because they know they are being studied
• The ethical implications of studying real crimes and real witnesses mean that controlled research is difficult

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Improving EWT: An Introduction

Given the problems with EWT, psychologists have developed improved interview techniques designed to help witnesses recall information more accurately while minimising the risk of contamination. The most important of these is the cognitive interview, which is covered in the next lesson.

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Key Points

• EWT is the account given by a witness to a crime or event.
• Loftus and Palmer (1974) showed that leading questions can distort EWT.
• Factors affecting EWT accuracy include: anxiety, leading questions, post-event discussion, time delay, and witness confidence.
• Mistaken eyewitness identification is the leading cause of wrongful convictions.
• Research into EWT has led to important changes in police interview procedures.
• Lab-based EWT research may lack ecological validity.

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Study case: Loftus and Palmer (1974) — Critical Contact Verbs

Aim: To investigate whether the wording of a question — specifically the verb describing a car collision — systematically changes a witness's estimate of speed, and whether misleading post-event information can create false memories of details that were not originally present.

Procedure: In the first experiment, 45 student participants watched seven short film clips of car accidents (each 5–30 seconds long). After each clip they completed a questionnaire. The critical question was: "About how fast were the cars going when they ___ each other?" The blank was filled with one of five critical contact verbs: smashed, collided, bumped, hit, or contacted. Participants were randomly allocated to one verb condition (independent-measures design).