Loftus and palmer (criminal classic study)

Two experiments are reported in which subjects viewed films of automobile accidents and then answered questions about events occurring in the films.

The question, “About how fast were the cars going when they smashed into each other?” elicited higher estimates of speed than questions which used the verbs collided, bumped, contucted, or hit in place of smashed.

On a retest one week later, those subjects who received the verb smashed were more likely to say “yes” to the question, “Did you see any broken glass?”, even though broken glass was not present in the film.

These results are consistent with the view that the questions asked subsequent to an event can cause a reconstruction in one’s memory of that event. 

The present research was conducted to investigate one such variable, namely, the phrasing of the question used to elicit the speed judgment.

The study was also used to test the innaccuracy of eye-witness testimony when verbs are changed accordingly in the questions following the viewed incident 

Forty-five students participated in groups of various sizes. Seven films were shown, each depicting a traffic accident

The length of the film segments ranged from 5 to 30 sec.

Following each film, the subjects received a questionnaire asking then1 first to, “give an account of the accident you have just seen,“ and then to answer a series of specific questions about the accident.

The critical question was the one that interrogated the subject about the speed of the vehicles involved in the collision. Nine subjects were asked, “About how fast were the cars going when they hit each other?”

Equal numbers of the remaining subjects were interrogated with the verbs smashed, collided, buiiiped, and contacted in place of hit.

TABLE 1 I I 1 SPEED ESTIMATES FOR THE VERBS USED IN EXPERIMENT 1

Verb Mean speed estimate Smashed 40.5

Collided 39.3

Bumpcd 38.1

Hit 34.0

Contacted 31.8 

The results of this experiment indicate that the form of a question (in this case, changes in a single word) can markedly and systematically affect a witness’s answer to that question.

The actual speed of the vehicles controlled little variance in subject reporting, while the phrasing of the question controlled considerable variance.

Two interpretations of this finding are possible.

First, it is possible that the differential speed estimates result merely from response-bias factors. A subject is uncertain whether to say 30 mph or 40 mph, for example, and the verb smashed biases his response towards the higher estimate.

A second inter- Ps pretation is that the question form causes a change in the subject’s memory representation of the accident. The verb smashed may change a subject’s memory such that he  “sees” the accident as being more severe than it actually was.

If this is the case, we might expect subjects to “remember” other details that did not actually occur, but are commensurate with an accident occurring at higher speeds. 

One hundred and fifty students participated in this experiment, in groups of various sizes. A film depicting a multiple car accident was shown, followed by a questionnaire.

The film lasted less than 1 min; the accident in the film lasted 4 sec. At the end of the film, the subjects received a questionnaire asking them first to describe the accident in their own words, and then to answer a series of questions about the accident.

The critical question was the one that interrogated the subject about the speed of the vehicles. Fifty subjects were asked, “About how fast were the cars going when they smashed into each other?”

Fifty subjects were asked, “About how fast were the cars going when they hit each other?” Fifty subjects were not interrogated about vehicular speed.

One week later, the subjects returned and without viewing the film again they answered a series of questions about the accident,

The critical question here was, “Did you see any broken glass?” which the subjects answered by checking “yes” or “no.” 

Verb condition Response Smashed Hit Control ~-

Yes

16 Smashed

7 Hit 

6 Control

No

34 Smashed

43 Hit

44 Control

G-  low. This is because the sample used was fairly limited, and could not be generalised to other groups. For example, Experiment 1 consisted of 45 students, because they were all from the same group of people, the findings cannot be representative of anyone other than students. Alongside this, as students they may have been taught prior about the innacuracies of eye- witness testimony, which would have made the results innacurate

R- Reliability. high. A standaridised procedure was  used, with each clip being shown for a specific length of time. This makes the experiment much more easily repeated by any other researchers

A- Applicabiliy to this study, as it can be used in interviewing for example, to let interviewers know not to ask a witness any leading questions, as it may heavily affect their response

V- One limitation of the research is that it lacked ecological validity. Participants viewed video clips rather than being present at a real life accident. As the video clip does not have the same emotional impact as witnessing a real-life accident the participants would be less likely to pay attention and less motivated to be accurate in their judgements.