Introduction to eyewitness testimony

Eyewitness testimony refers to the account given by someone who has directly observed an event, such as a crime or accident. These descriptions often assist police investigations and may serve as evidence in court proceedings against those responsible.

A key issue in eyewitness testimony is the accuracy of identifications, particularly when witnesses are asked to pick out individuals from line-ups. Line-ups are arrangements of photographs or people presented to witnesses to identify a suspect.

False positive responses in eyewitness testimony

A false positive response occurs when a witness incorrectly identifies someone as being present at the event, even though that person was not involved. This can lead to wrongful accusations or convictions. Research suggests that children may be more prone to false positives due to social factors, such as feeling pressured to please authority figures like interviewers.

Background and aims of the study by Pozzulo et al.

Previous research has shown that children and adults have similar success rates in correctly identifying targets from line-ups where the actual person (target) is present, known as target-present line-ups. However, children, even up to age 13, struggle more than adults to correctly reject line-ups where the target is absent, known as target-absent line-ups. This results in higher false positive rates among children.

These differences might stem from social pressures, such as the desire to satisfy an interviewer who is seen as an authority, rather than from memory weaknesses.

Aims of the study

• To explore differences between children and adults in recognising human faces
• To explore differences between children and adults in making false positive identifications in target-absent versus target-present line-ups
• To explore differences between children and adults in performance with human faces compared to cartoon characters.

Method of the study

This was a laboratory experiment, which is a controlled research method conducted in an artificial setting to test hypotheses by manipulating variables. It used a mixed design, combining independent measures (comparing separate groups) and repeated measures (where the same participants experience all conditions).

Independent variables

• Age of participants: children (aged 4–7 years) versus adults (aged 17–30 years)
• Type of target faces: familiar cartoon characters or unfamiliar human faces
• Type of line-up: target-present (includes the actual target plus similar-looking distractors, called foils) or target-absent (only foils, no target).

Dependent variables

• Correct identification rates in target-present line-ups (how often participants accurately picked the target)
• Correct rejection rates in target-absent line-ups (how often participants correctly said no one matched).

Sample

The study involved 59 children aged 4–7 years, recruited from three private schools in Canada, and 53 adults aged 17–30 years, drawn from a university introductory psychology participant pool in Eastern Ontario. The sampling technique was not specified in the original article.

Data was collected using a questionnaire to gather demographic details (such as age, gender, and time spent watching cartoons) and familiarity with the cartoons. Identification tasks used pointing on a PowerPoint for children or a matching sheet for adults.

Procedure of the study

Participants were tested individually to ensure focused responses.

Steps in the procedure

1. They watched four short colour videos, each followed by a photo line-up. Two videos featured familiar cartoon characters (Dora and Diego), and two featured unfamiliar human actors (one male, one female).
2. After each video, they completed a filler task: open-ended questions like "What did the cartoon character/person look like?" and "Do you remember anything else?" This acted as a distraction to mimic real-world delays in recall.
3. They then viewed photo line-ups with four black-and-white headshot images. In target-present line-ups, one was the target and three were foils. In target-absent line-ups, all four were foils.
4. Participants were instructed to point to the matching photo if present, or to a separate box if not. They were explicitly told that the target might not be there to avoid misleading them.

Controls in the procedure

• Videos and the order of faces in line-ups were randomised for each participant to prevent order effects, where the sequence might influence responses.
• Standardised instructions were provided to all participants before the line-ups.
• Experimenters wore consistent "professional-casual" clothing to maintain a neutral appearance.

Ethical considerations

• Ethical guidelines were followed to protect participants, especially children who are considered a vulnerable group.
• Written informed consent was obtained from parents for children and directly from adults.
• No deception was used; participants were told targets might be absent.
• Children were monitored for signs of anxiety, stress, or fatigue to minimise harm, as they may be less able to assert their right to withdraw.
• Additional protections included reassuring children they could stop without consequences and starting with craft activities to ease them into the experiment.

Results of the study

Quantitative data was collected, measuring identification accuracy as proportions (rates between 0 and 1).

Results for target-present line-ups

Both groups performed better with familiar cartoons than unfamiliar human faces. Children were notably worse than adults with human faces.

Results for target-absent line-ups

• Correct rejection rates were higher for cartoons than human faces in both groups.
• Children showed much higher false positive responses overall compared to adults.
• Children - 0.74 for cartoons, 0.45 for human faces
• Adults - 0.94 for cartoons, 0.70 for human faces

These differences were statistically significant, indicating reliable patterns.

Conclusions of the study

Children's high accuracy with cartoons in target-present line-ups suggests that cognitive factors, like poor memory, do not explain their errors in target-absent scenarios. Instead, social factors are key: children may feel pressured to make a positive identification to please the researcher, even if unsure.

Overall, children are less accurate with human faces and more prone to false positives than adults, highlighting the influence of social expectations over memory deficits.

Evaluation of the study

Strengths

• Validity - The repeated measures design controlled for participant variables, such as differences in memory skills, ensuring results reflected the manipulated variables rather than individual differences.
• Objectivity - Quantitative data (correct or incorrect responses) left no room for researcher bias in interpretation.

Weaknesses

• Reliability - While instructions and procedures were standardised, the filler task questions varied slightly between participants, potentially influencing recall and reducing consistency.
• Generalisability - The sample was limited to children from private schools and university students, so findings may not apply to broader populations.

Issues and debates in the study

Application to everyday life

The study shows how eyewitness testimonies, especially from children, can be swayed by social expectations. This has practical value for developing police guidelines, such as training officers to reduce pressure during child interviews, potentially lowering false positives in target-absent line-ups and preventing miscarriages of justice.

Individual versus situational explanations

When identifying cartoon characters in target-present line-ups, children and adults perform similarly, suggesting individual factors like age or memory are less influential than situational ones, such as familiarity with the stimuli. The higher false positives in children point to situational factors, like perceived social pressure from authority figures, as a stronger explanation for errors than innate individual differences.

Use of children in psychological research

Young children are vulnerable to social pressure, so extra safeguards are essential. In this study, parental consent was obtained since children may not fully grasp research risks. They were reassured about their right to withdraw without penalty, and relaxing activities preceded the tasks to minimise distress. These measures highlight the ethical balance needed when involving young participants.