Human Memory
Lesson 15
Human Memory EWT Misleading and Leading Questions Produced by
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Key Terms Eyewitness Testimony (EWT) • EWT can be defined as the evidence given in court or in a police investigation by someone who has witnessed a crime or an accident. Leading Questions • A question phrased in such a way as to prompt a particular kind of answer. ‘Was the man wearing a hat?’ is a leading question since it suggests that the man was actually wearing a hat.
Introduction • One of the main factors affecting the accuracy of memory for an event seems to be what happens after the event has taken place. The memories laid down at the time seem to be quite fragile and subject to distortion by post event information. • It appears that misinformation can introduce serious errors into eyewitnesses recall of events. • Loftus (1992) called this ‘misinformation acceptance’ where people accept misleading information after an event and absorb it into their memory for the actual event.
Key Study – Loftus (1992) • Loftus and her colleagues have typically used an experimental technique where participants are shown a film of an event such as a road traffic accident. • They are then exposed to some kind of post-event information – this often takes the form of leading questions – and they are then tested for their memory of the original event. • False information given to witnesses after the event can serve to change the original memory by removing some elements and inserting others.
• Loftus showed participants a film of the events leading up to a car accident. After they had seen the film, participants were divided into a control group and an experimental group. • The control group was asked questions consistent with what they had actually seen (‘How fast was the white sports car going when in passed the Stop sign?’) • The experimental group was asked a question that included misleading information (How fast was the white sports car travelling when it passed the barn while travelling along the country road?’)
• All the participants were then asked more questions about the accident. • 17% of the participants in the experimental condition reported seeing a barn in the original film. • Only 3% of the participants in the control condition made this error. • Loftus concluded that some of the participants given the misleading post-event information had actually absorbed this with their original memory for the event and now really believed they had seen a barn.
Methodical Issues • This was a controlled laboratory experiment. Loftus used realistic material, i.e. film footage of a car accident. However, the situation was still artificial because participants were aware they had to pay attention. In real life EWT, witnesses would not be pre-prepared. • Some critics of Loftus have said that her participants were subject to demand characteristics. However, Loftus refutes this criticism.
Ethical Issues • Investigators are always expected to obtain consent from their participants. However, in this case, Loftus could not have obtained fully informed consent. So there was some form of deception. • Deception should be avoided in scientific studies but it is sometimes necessary to avoid participants guessing the hypothesis. • Some critics of Loftus have said that her participants were subject to demand characteristics. However, Loftus refutes this criticism.
Key Study – Loftus & Zanni (1975) • Loftus and her colleagues showed participants a brief film clip of a car accident and then asked a series of questions. • Half the participants were asked whether they had seen ‘a’ broken headlight and the other half were asked if they had seen ‘the’ broken headlight. • Although there was no broken headlight in the film, 17% of the participants asked about ‘the’ broken headlight reported seeing one as opposed to 7% of the participants asked about ‘a’ broken headlight.
Key Study – Loftus & Palmer (1974) • Loftus and her colleagues showed participants a film clip of a car accident and then asked a series of questions about events leading up to the accident. • One crucial question concerned the speed of the car on impact. • One group was asked ‘How fast were the cars going when they hit each other?’ • Other groups were asked the same question , but in each case the verb was changed to either ‘smashed’, ‘bumped’, ‘collided’ or ‘contacted’.
• The verb used significantly affected the speed estimates – ‘smashed’ produced the highest estimate and ‘contacted’ produced the lowest estimate. • A week later, when questioned again, participants who had been asked the ‘smashed’ version of the question were more likely to report having seen a broken glass at the scene of the accident, even though they had been none.
Examiners Note • Research into EWT has obvious real-life applications. However, Loftus’s experimental technique does not exactly mimic real life situations. • In genuine situations, onlookers are not expecting anything to happen and are, therefore, not paying attention in the way they would in an experimental set-up. • They are also unlikely to be as emotionally affected by the experience as they would be by a real life crime or accident.
Examiners Note • Be careful when you are reporting the results of such studies. Note that not all of the misled group were fooled by the post-event information.