Factors Affecting the Accuracy of Memory

Memory is not a perfect recording of events. Our memories are reconstructive — they can be distorted, altered, or completely fabricated without us realising it. Several factors affect how accurately we remember events, which has important implications for everyday life and for the criminal justice system.

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Interference

As covered in the previous lesson, interference from similar memories can reduce accuracy. When we have multiple similar experiences, details from one event can become confused with details from another. This is particularly problematic in situations where accurate recall is important, such as eyewitness testimony.

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Context and State

Memory accuracy is influenced by whether the context (external environment) and state (internal condition) at retrieval match those at encoding. When there is a mismatch, recall is less accurate. This means that a witness recalling an event in a police station may be less accurate than if they returned to the scene of the crime.

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Emotional State and Anxiety

Emotions can significantly affect memory accuracy:

Anxiety and Memory

The relationship between anxiety and memory is complex. Some research suggests that moderate anxiety can improve memory for central details of an event, while high anxiety may impair memory or cause a focus on specific threatening details at the expense of peripheral information.

Weapon Focus Effect

Johnson and Scott (1976) demonstrated the weapon focus effect. Participants in a waiting room heard an argument in the next room. In one condition, a person emerged carrying a pen with grease on their hands. In the other condition, the person emerged carrying a knife covered in blood.

• Participants in the pen condition correctly identified the person from a set of photos 49% of the time
• Participants in the knife condition correctly identified the person only 33% of the time

The presence of a weapon drew participants' attention away from the person's face, reducing the accuracy of their memory for what the person looked like. This is because anxiety narrows attention to the source of the threat (the weapon) at the expense of other details.

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Leading Questions

One of the most important factors affecting memory accuracy is the use of leading questions. A leading question is one that is worded in a way that suggests or implies a particular answer.

Loftus and Palmer (1974)

Loftus and Palmer (1974) conducted a landmark study on the effect of leading questions on memory. They showed 45 participants a film of a car accident and then asked them to estimate the speed of the cars using different verbs:

"About how fast were the cars going when they [verb] each other?"

Verb Used	Mean Estimated Speed (mph)
Smashed	40.8
Collided	39.3
Bumped	38.1
Hit	34.0
Contacted	31.8

Key finding: The verb used in the question significantly influenced participants' speed estimates. "Smashed" produced the highest estimate, and "contacted" the lowest. This demonstrates that the wording of a question can distort memory for an event.

flowchart LR
    A["Original event<br/>car crash film"] --> B[Encoding into memory]
    B --> C{"Leading question<br/>verb used?"}
    C -->|smashed| D["40.8 mph estimate<br/>32% recall broken glass"]
    C -->|hit| E["34.0 mph estimate<br/>14% recall broken glass"]
    C -->|contacted| F["31.8 mph estimate<br/>low false recall"]
    D --> G["Distorted memory<br/>trace integrated"]
    E --> G
    F --> G

In a follow-up study, participants were asked one week later: "Did you see any broken glass?" (There was no broken glass in the film.) Those who had been asked the "smashed" question were more than twice as likely to falsely report seeing broken glass compared to those asked the "hit" question. This suggests that leading questions can create false memories, not just alter estimates.

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Post-Event Discussion

Talking to other witnesses after an event can also distort memory. When witnesses discuss what they saw, they may incorporate details mentioned by others into their own memory, even if they did not personally observe those details. This is called post-event discussion or the misinformation effect.

Gabbert et al. (2003) showed pairs of participants different videos of the same event. When the participants discussed the event together, many later recalled details from their partner's video that they had not actually seen themselves. This phenomenon is known as memory conformity.

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Age

Research suggests that both very young children and older adults may have less accurate memories:

• Young children may be more susceptible to suggestion and leading questions
• Older adults may have more difficulty with source monitoring — remembering where information came from

However, age effects vary widely between individuals, and it would be an oversimplification to say that all children or older adults have unreliable memories.

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Implications for Eyewitness Testimony

The factors described above have profound implications for the reliability of eyewitness testimony (EWT) in the criminal justice system:

• Witnesses are often questioned using potentially leading questions
• They may discuss events with other witnesses before giving statements
• High anxiety during a crime may impair memory accuracy
• The weapon focus effect may reduce ability to identify a suspect
• The passage of time allows for more interference and decay

These findings have led to important changes in how police interview witnesses, including the development of the cognitive interview (covered in a later lesson).

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Key Points

• Memory is reconstructive and can be distorted by many factors.
• Interference from similar memories reduces accuracy.
• Context and state mismatches at retrieval impair recall.
• Anxiety and the weapon focus effect can narrow attention and reduce accuracy (Johnson and Scott, 1976).
• Leading questions can distort memories and create false memories (Loftus and Palmer, 1974).
• Post-event discussion can lead to memory conformity (Gabbert et al., 2003).
• These factors have significant implications for the reliability of eyewitness testimony.

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Study case: Bartlett (1932) — The "War of the Ghosts"

Aim: To investigate how memory for an unfamiliar story is altered over time, and to explore the role of schemas (pre-existing mental frameworks shaped by culture and expectation) in shaping recall. Bartlett wanted to demonstrate that memory is reconstructive rather than a passive recording.