Study 1 - Loftus and Palmer (1974)



Study 1 - Loftus and Palmer (1974)

Reconstruction of automobile destruction: an example of the interaction between language and memory

Field of psychology: Cognitive

1. CONTEXT AND AIMS

Context

The scene above is familiar to anyone who has ever watched TV. It is a cornerstone of our legal system that without evidence, a person can not be found guilty of a crime. This is why all witnesses must swear in court to only tell the truth. However, what happens if the eyewitness believes that they are telling the truth, but really they are providing testimony which is not 100% accurate? When a witness to a crime has nothing but their own memory to rely on, can we be sure that their testimony is a real account of what actually happened?

What is eyewitness testimony (EWT)?

Eyewitness testimony is a legal term, referring to the use of eyewitnesses to give evidence in court.

What does the Innocence Project suggest about the importance of (EWT)?

The study by Loftus and Palmer took place in 1974. Why is this relevant to the context?

One reason why the accuracy of EWT is often very poor could be because of leading questions used by the police after the event. Information received after an event can have a retroactive interfering effect on our recollection; in other words, retroactive interference occurs when later learning interferes with previous learning; i.e., incoming information gets integrated and confused with our existing knowledge.

Previous research has suggested that the mind does not work like a camera. Our mind does not just take a picture of what it sees, and then reproduces this memory accurately. Our memories can easily be altered by other information.

This can be demonstrated in the study by Carmichael (1932). What do the results of his experiment suggest?

Marshall (1969) reports that when Air Force personnel, who knew in advance that they would be asked to estimate the speed of a vehicle, actually observed a car travelling at 12 mph. their estimates ranged from 10 to 50 mph. Given that there are such a range of estimates, it suggests that there might be variables which may cause these inaccuracies such as the phrasing of a question to elicit a judgement of speed. These results also show us that humans are poor at estimating speed.

It was Filmore (1971) who suggested that the words smashed and hit may imply different rates of speed. These words lead the listener to assume different consequences to the impacts to which they are referring, with hit being perceived as gentler than smashed.

Aims

Loftus and Palmer’s experiment was actually two experiments. They wanted to investigate in general how accurate or inaccurate memory was. Specifically they wanted to see the effect of _____________________ upon estimates of ____________________.

Experiment 1

To see if the speed estimates given by participants upon watching a video of a car crash would be influenced by the wording of the question asked. They wanted to see if participants who were asked a question with the word “hit” in it would give a different estimate of speed than those who were asked the same question but with the word “smashed”.

Experiment 2

Loftus and Palmer also wanted to see if the leading questions just changed the responses given to the questions, or whether the participant’s memories had actually altered as a result of the leading questions.

2. PROCEDURES

As stated previously, Loftus and Palmer carried out two experiments. You need to know detailed procedures for both of them, as well as participant numbers.

Use the information on pg 93 and the original text, complete the following two tables. When outlining the procedure, be as detailed but as clear as you can. Imagine that someone else wanted to follow your description to repeat the experiment. State what were the experimental and control groups (if relevant). You can use bullet points if you wish.

Experiment 1

|Number and make-up of participants | |

|Research method used | |

|Experimental design | |

|Independent variable | |

|Dependant variable | |

|Outline the procedure | |

| | |

Experiment 2

|Number and make-up of participants | |

|Research method used | |

|Experimental design | |

|Independent variable | |

|Dependant variable | |

|Outline the procedure | |

| | |

Q1: Why were the participants not told about the true aims of the study?

Q2: Why were the participants given a series of questions rather than just the critical question alone?

Q3: In the first experiment, the order of the videos shown was varied from participant to participant. Why?

Q4: What was the point of having a control group in the second experiment?

3. FINDINGS AND CONCLUSIONS

Experiment 1

Findings

A Average estimate of speed for the four videos (all participants)

|Actual speed of car |Mean speed estimate |

|crash |(mph) |

|20 |37.7 |

|30 |36.2 |

|40 |39.7 |

|40 |36.1 |

B Average speed given for the different verbs used

|Verb used in critical |Mean speed estimate |

|question |(mph) |

|Smashed |40.5 |

|Collided |39.3 |

|Bumped |38.1 |

|Hit |34.0 |

|Contacted |31.8 |

Summarise the results of table A

Summarise the results of table/graph B

Conclusions

Explain how the results above support the theory of leading questions

Loftus and Palmer give two alternate explanations of the results. Explain what is meant by:

|Biased response |Change in memory |

Experiment 2

Findings

A Average estimate of speed for the two verbs

|Verb Used in critical |Mean speed estimate |

|question |(mph) |

|Hit |10.46 |

|Smashed |8.00 |

B No of ppts who claimed to see broken glass

|Condition |Yes |No |

|Hit |7 |43 |

|Smashed |16 |34 |

|Control |6 |44 |

|Condition |1-5 |6-10 |11-15 |16-20 |

|Hit |.09 |0.27 |0.41 |0.62 |

|Smashed |.06 |.09 |0.25 |0.50 |

C – Probability of saying yes to the broken glass question for different speed estimates

Summarise the results of table A

Summarise the results of table/graph B

Summarise the results of table C

Conclusions

In experiment 1, Loftus and Palmer gave two alternate explanations of the results. Which explanation do the results of experiment 1 support?

Loftus and Palmer suggest that memory is made up of two types of information. What are these and how do they combine to make a memory? (Pg 558 of original text and pg 94 in textbook)

Apply the above to explain the results of this experiment.

4. EVALUATING THE METHODOLOGY (pg 96)

Method: The methodology used in this study was a lab experiment. What was a strength of using this methodology is this study?

________________________________________________________________________________ _____________________________________________________________________________

______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

In the first experiment, each of the verbs only had 9 participants. Why could this be an issue?

____________________________________________________________________________________________________________________________________________________________________________________________

____________________________________________________________________________________________________________________________________________________________________________________________

Reliability: This study has been replicated many times, and similar findings have been produced. What does this suggest about the reliability of the study?

____________________________________________________________________________________________________________________________________________________________________________________________

____________________________________________________________________________________________________________________________________________________________________________________________

Validity: What aspects of the study affect the ecological validity?

The setting: ____________________________________________________________________________________

__________________________________________________________________________________ __________________________________________________________________________________

___________________________________________________________________________________

The participants watched a video of a car crash, not a real car crash: ________________________

________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

The participants were aware that they were in a study: __________________________________

________________________________________________________________________________ ________________________________________________________________________________ _______________________________________________________________________________

Sampling: The sample consisted of US college students. Could there be issues with generalisability? In what way are these participants different from the target population (all people)? __________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________

Ethical issues: refer back to your notes on ethics. Can you see any issues with this study? _______________________________________________________________________________ ______________________________________________________________________________ _______________________________________________________________________________ ________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________

5. CRITICALLY ASSESS WITH REFERENCE TO ALTERNATIVE EVIDENCE

Match the study to the conclusion

|1: Loftus and Zanni (1975) | |This research contradicts Loftus and Palmer, as it |

|Showed participants a film of a car accident. Some | |suggests that in some circumstances, leading questions |

|participants were asked “Did you see a broken headlight?” | |have a limited effect on memory. It may be that the |

|whereas others were asked “Did you see the broken | |information to be remembered in this study was less |

|headlight?” 7% of those asked about a broken headlight | |subjective than estimating speed. |

|reported seeing one, whereas 17% asked about the headlight| | |

|reported one. (There was not one in the video) | | |

|2: Loftus (1979) | |This study develops the research into EWT. Whereas |

|Showed participants a series of pictures of a man stealing| |Loftus and Palmer investigated the effect of leading |

|a red wallet from a woman’s bag. 98% of participants were | |questions in altering memories of real events, this |

|able to identify the colour correctly. Later, Loftus used | |research suggests that leading questions can even plan |

|leading questions to try and alter the participants | |memories that were never there. It develops the theory |

|recall. However, they persisted in describing the purse as| |that verbal information can alter memory. |

|red. | | |

|3:Buckhout (1980) | |A criticism of Loftus and Palmer was that the |

|A 13 second film clip of a mugging was shown on TV. An | |participants knew that they were in a study, and so |

|identity parade of six suspects was later shown and | |their behaviour may have been unnatural. This study |

|viewers asked to phone in and say who they thought had | |gets around this issue by demonstrating that recall in |

|done it. | |real life, when participants do not know that they will|

|Given that there were only six suspects, chance alone | |be asked to recall is still very poor. |

|would suggest that 17% would get it right. In fact only | | |

|14% identified the person correctly. | | |

|4:Yullie and Cutshall (1986) | |This study has the advantage of letting us see the |

|Interviewed 13 people who had witnessed an armed robbery | |effect of leading questions on real life eyewitnesses. |

|in Canada four months after. They included two misleading | |It suggests that the results of Loftus and Palmer only |

|questions. They found that the participants were not led | |apply in a laboratory setting, not in real life cases. |

|by the leading questions, and the accounts that they gave | |It supports the argument that Loftus and Palmer’s |

|were very similar to those in their initial witness | |research lacks ecological validity. |

|statements | | |

|5: Loftus and Pickrell (1995) | |A criticism of Loftus and Palmer’s experiment is that |

|Interviewed participants about events in childhood, | |judging speed is complex, and therefore the |

|planting a false memory of being lost in a mall as a child| |participants more prone to being led by leading |

|(an event that never happened). 20% of the participants | |questions. This research however demonstrates that |

|came to believe that this event had actually happened, and| |leading questions can actually cause participants to |

|some even clung to the memory after being debriefed. | |remember something that was not there. This supports |

| | |Loftus and Palmer, as it provides more evidence that |

| | |leading questions can alter the response given. |

|6: Braun et al (2002) | |This research build upon the results of Loftus and |

|Participants who had visited Disneyland as a child were | |Palmer, as it suggests that misinformation does not |

|told that they would be evaluating advertisements for it. | |need to be verbal for it to have an effect on recall. |

|Group one were given an ad with no characters on it, group| |False memories can be established by non verbal/visual |

|two were given the same ad with a cardboard Bugs Bunny in | |information. |

|the corner of the room; group three were given an ad that | | |

|had bugs bunny on it, and the group four got the Bugs | | |

|Bunny ad and the cardboard Bugs Bunny. When asked later | | |

|about having met Bugs Bunny as a child, 30% of group 2 and| | |

|40% of group 4 recalled meeting him. (Bugs Bunny is not | | |

|Disney, so this was a false memory) | | |

Use three colours to highlight research that supports, contradicts, or develops Loftus and Palmer’s research.

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“I do solemnly, sincerely and truly declare and affirm that the evidence I shall give shall be the truth, the whole truth and nothing but the truth”

“A leading question is a question that either by it’s form or content, suggests to the wittness what answer is desired, or leads him to the desired answer.

Elizabeth Loftus

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