Loftus & Palmer (1974)

## Aim

The aim of the research was to investigate whether the use of leading questions would affect estimation of speed.

## Procedure

The researchers predicted that using the word ‘smashed’ would result in higher estimation of speed than using the word ‘hit’. The independent variable was the different words used in the critical question and the dependent variable was estimation of speed. 45 students participated in the experiment. They were divided into five groups of seven students. Seven films of traffic accidents were shown and the length of the films ranged from 5 to 30 seconds. These films were taken from driver’s education films.

When the participants had watched a film they were asked to give an account of the accident they and seen and then they answered a questionnaire with different questions on the accident with one question being the critical question where they were asked to estimate the speed of the cars involved in the accident. There was one critical question which was the one asking the participant to estimate the speed of the cars involved in the accident. The participants were asked to estimate the speed of the cars. They were asked the same question but the critical question included different words. Nine participants were asked “About how fast were the cars going when they hit each other?" The critical word "hit’" was replaced by ‘collided’, ‘bumped’ or ‘smashed’ or’ contacted’ in the other conditions which each had nine participants answering the question.

## Results

The mean estimates of speed was highest in the ‘smashed’ condition (40.8 mph) and lowest in the ‘contacted’ group (31.8 mph).

## Conclusion

The results indicate that the critical word in the question consistently affected the participants’ answer to the question. The researchers argued that it may be that the different speed estimates is the result of response-bias, i.e. the participant is uncertain about the exact speed and therefore a verb like "smashed" biases his or her response towards a higher estimate. It may also be that the way the question is formed result in a change in the participant’s mental representation of the accident, i.e. the verb "smashed" activates a cognitive schema of a severe accident that may change the participant’s memory of the accident. This distortion of memory is based on reconstruction so that it is not the actual details of the accident that are remembered but rather what is in line with a cognitive schema of a severe accident. This interpretation is in line with Bartlett’s suggestion of reconstructive memory due to schema processing.

In conclusion, it seems that participants’ memory of an incident could be changed by using suggestive questions.

## Evaluation

The experiment was conducted in a laboratory and the participants were students. Lab experiments may be problematic in the sense that they do not necessarily reflect how people remember in real life. There may be a problem of ecological validity and it has been argued that this is the case here. A support for this point could be that the films shown in the experiment were made for teaching purposes and therefore the participants did not experience the same as if it had been a real accident.

However, strength of the experimental method is that confounding variables can be controlled so that it is really the effect of the independent variable that is measured. This was the case in this experiment and Loftus and Palmer could rightfully claim that they had established a cause-effect relationship between the independent variable (the critical words) and the dependent variable (estimation of speed). The fact that the experiment used students as participants has also been criticized because students are not representative of a general population. Another problem could be demand characteristics since the participants knew they participated in an experiment. This could affect their answers because they responded to what they thought would be appropriate answers. If this is the case it was not their memory that was tested.

## Aim

The aim of the experiment was to investigate if participants who had a high speed estimate in the first part of an experiment would say that they had seen broken glass in the second part of the experiment. The researchers hypothesized that this would happen.

## Procedure

150 students participated in this experiment. They were divided into groups of different sizes. They were shown a 1-minute film depicting a multiple car accident lasting around 4 seconds. After seeing the film the participants answered a questionnaire. First they described the accident in their own words, and then they had to answer a number of other questions. Fifty participants were asked:” About how fast were the cars going then they smashed into each other?” Fifty participants were asked:” About how fast were the cars going when they hit each other?” The remaining fifty participants were not asked to estimate speed.

After one week the participants came back to the laboratory to answer some questions about the accident. There was one critical question this time in a list of a total of 10 questions and it was placed randomly in the list in the questionnaire. The critical question was:” Did you see any broken glass?” The participants simply had to answer “yes” or “no”. In fact there was no broken glass in the accident the participants had seen but the researchers assumed that broken glass was associated with high speed.

## Results

In the ‘smashed’ condition 16 participants said yes to having seen broken glass compared to 7 in the ‘hit’ condition. 6 participants in the control condition answered ‘yes’ to the question. 34 participants in the ‘smashed’ condition answered ‘no’ to the question compared to 43 in the ‘hit’ condition. Although most of the participants accurately reported no broken glass, more of the participants in the ‘smashed’ condition said they saw broken glass.

 Yes
 No

## Conclusion

The researchers argued that the results of the second experiment provided further support for the theory of reconstructive memory and schema processing. The wording of the critical question led to higher speed estimates in the first part of the experiment and this also had consequences for how participants answered in the second part of the experiment. Loftus and Palmer suggest that participants are influenced by the perception of the event but also of the post-event information provided by the critical question. The researchers argue that this information may be integrated in such a way that it is difficult to say where it came from when the participants try to recall the event. The verb used in the critical question provides further information to the participant about the accident. The word ‘smashed’ gives the participant the idea of an accident that is severe and therefore he or she is more likely to think that there was broken glass.

The results of this experiment can be interpreted in terms of Bartlett’s theory of reconstructive memory, i.e. people tend to change details of an event when they try to remember it. This is probably also what happened when the participants in Loftus and Palmer’s study tried to remember the original information when they were given information about the speed of the cars through the use of the either ‘hit’ or ‘smashed’. The participants may have used their past knowledge of serious car accidents to make the decision of whether or not they had seen broken glass (schema processing).

## Evaluation

This study can also be accused of lacking ecological validity and therefore it may be difficult to generalize the findings to real life. The comments made on the first experiment also apply to the second one.