Loftus and Palmer (1974)

Specification

Loftus and Palmer (1974) Reconstruction of auto mobile destruction: An example of the interaction between language and memory.

Aim(s)

To see if the phrasing of a question would affect estimates of speed, applying these findings to the idea of leading questions in court.

A leading question is one that suggests to the witness what answer is desired or leads him or her to the desired answer.

Experiment 1

Procedure

45 students were put into groups.

7 films were shown, each involving a traffic accident, with each film lasting 5-30 seconds. The films were segments from longer driver’s education film borrowed from the Evergreen Safety Council and the Seattle Police Department.

After every film the participants had a questionnaire to fill in.

First they were required to give an account of the accident, and then to answer to specific questions.

The critical question was the one asking about the speed of the vehicle.

9 participants were asked “about how fast were the cars going when they hit each other?” and equal numbers of the rest were asked the same question, but with the word “hit” being replaced by “smashed”, “collided”, “bumped”, or “contacted”.

The same procedure was followed for each film, however the order of the films was randomised for each group.

4 of the 7 films used contained staged crashes originally designed to illustrate what can happen to human beings when cars collide at various speeds. In these cases, the speed of the cars was known. One was travelling at 20 mph, one was at 30 mph and two were at 40mph.

Results

The use of the verb “smashed” gave the highest mean estimate of speed and “contacted” the lowest mean estimate. “Collided”, “bumped” and “hit” had speed estimates that decreased as per the perceived severity of the verb.

The mean estimates of speed for the four films where the actual speed was known were: 37.7, 36.2, 39.7, and 36.1 mph, respectively. In agreement with previous work, people are not very good at judging how fast a vehicle is traveling.

Conclusions

It was concluded that a leading question, can affect a witness answer.

Perhaps the participant is uncertain in judging speeds, for example between 30 and 40 mph, so he or she uses the word in the question to help.

It is possible that the question changes the memory of the accident so the participant sees the accident as more severe if the word “smashed” is used. If this is the case, we might expect participants to “remember” other details that did not actually occur.

Experiment 2

Aim(s)

The second experiment was designed to provide additional insights into the origin of the differential speed estimates

Procedure

150 participants were sampled and in groups of various sizes they watched a film with a multiple car accident, this was followed by completing a questionnaire.

The film lasted less than 1 minute of which the accident was 4 seconds.

The questionnaire at the end of the film asked participants to describe the accident in their own words and then to answer more questions. Some were asked about the speed using the word “smashed” as part of the questions, some were asked the same question with the word “hit” replacing “smashed”, and some were not asked about speed. This group acted as a baseline control group measure.

One week later the participants came back but were not shown the film again. They were asked more questions, including “Did you see any broken glass?”. There was no broken glass in the film, but it was thought that the word “smashed” used in the question the week before would lead to more broken glass being “remembered” by those participants.

Results

The mean estimate of speed for the question including the word “smashed” was 10.46mph and for “hit” it was 8mph. These differences were found to be statistically significant.

A chi-square test was conducted on these responses and was found to be significant beyond the .025 level. The probability of saying “yes” to the question about broken glass is 0.32 when the verb smashed is used, and 0.14 with hit. So, smashed leads to more “yes” responses and to higher speed estimates.

Table 2 shows the number of participants that answered yes or no to the question of ‘Did you see any broken glass’.

Conclusions

The question about “how fast were the cars going when they smashed into each other?” led to higher estimates of speed than the same question asked with the verb smashed replaced by hit. This also had consequences for how questions are answered a week after the original event occurred.

Loftus and Palmer proposed that two kinds of information go into memory. The first is information is from the perception of the original event; the second is external information supplied after the fact. These two sources of information become integrated so that we are unable to tell from which source specific detail is recalled. All that is available is one “memory”.

Past Paper Questions

Loftus and Palmer (1974) concluded from their data in Table 4 that a change of verb in leading questions could affect eyewitness recall of a car accident. Explain why Loftus and Palmer (1974) came to this conclusion. (3)
Assess the credibility of the study by Loftus and Palmer (1974). (8) January 2019

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