Loftus and Palmer

Background 

Schema theory proposes that memory is influenced by what an individual already knows, and that their use of past experience to deal with a new experience is a fundamental feature of the way the human mind works.  Knowledge is stored in memory as a set of schemas – simplified, generalised mental representations of everything an individual understands by a given type of object or event based on their past experiences. 

The schema forms part of Bartlett’s theory of reconstructive memory which forms the basis for Loftus and Palmer’s study into EWT.

Theory 

Memory involves interpreting things we see or hear. This suggests memory can be influenced or biased by features of the situations we are in. Loftus and Palmer conducted many studies investigating ways in which memory can be distorted, many of which show that EWT is highly unreliable because it can be influenced by such things as subtle differences in the wording of questions. This study focuses on the effects of ‘leading questions’ on an individual’s ability to accurately remember events. The expectation was that any information subtly introduced after the event through leading questions – questions phrased in a way suggesting the expected answer – would distort the original memory

Experiment One 

In the first experiment there was 45 students participating. The students were divided into 5 groups of 9. 

Experiment Two 

There were 150 students in this experiment that were divided into 3 groups of 50. 

Method of Sample  

The method of sampling was volunteering as the sample was taken from the university that the experiment was taking place in. 

A weakness of the sample for the Loftus and Palmer's study into the effects of language on the memory is that all of the participants were students from a university meaning there is a low generalisability of the sample to a wider population. For example in experiment one of the study there were 45 students, which  also could be considered a small sample, and in experiment two there were 150 students. Therefore the results and conclusions drawn from the experiment may not be applicable to older citizens, who potentially have lower cognitive ability, which means the research may not be upheld as useful. 

A strength of the sample for Loftus and Palmer's research is that the sample is quite large.For example in expeiment two of the study there was 150 participants, which was conserable larger than the 45 participants in the first experiment. Therefore the generability of the research is increased as there is less chance of biases within the sample, such as gender bias or ethnocentrism. 

Two experiments were conducted to see whether a person's memory of an event could be affected by leading questions. The first experiment also tested the theiry that eye witnesses are not very accurate when trying to estimate speed of vehichles. 

Both of the experiments were conducted in a laboratory, using an independent measures design. 

A strength of method in the Loftus and Palmer study is that a highly controlled laboratory experiment was conducted, allowing for good replicability. For example Loftus and Palmer controlled the video clips that participants watched as they all watched the same seven video clips and also ensured that participants were all given the same questionnaire. This means that the experiment fulfils the scientific criteria and so increases the reputation of psychology as a science on the whole.

A weakness of the laboratory experiment method is that the ecological validity is reduced. For example in this study the participants were informed they would be watching seven clips of a road traffic accident and were prepared to recall the events of the accident. However in the real world accidents happen spontaneously so memories of events will be different without having prior knowledge of the need to recall the event. Therefore this study may suggest psychology is not useful as it cannot produce accurate results without potentially causing psychological harm. 

A strength of using an independent measures design in this study is order effects could be counteracted. For example in this study the participants were presented with  a different order of video clips. This prevented the participants becoming bored of the experiment and also helps prevent demand characteristics meaning the results have a greater internal validity as the results reflect on the participant's initial answers rather than an answer swaying towards a potential hypothesis. 

A weakness of using independent measures design in this study is that participant varibales may  have affected the results of the study. For example a non driver within the sample may be less accurate at estimating speed as they are inexperienced in measuring speed, unlike an experienced driver, who is more likely to be able to estimate speed accurately. Therefore the results of the experiment coud be considered as less reliable as the results may differ if all non drivers were used as a sample. 

The Independent Variable 

The verb used in the critical question: "About how fast were the cars going when they hit/smashed/collided/contacted/bumped eachother?" 

The Dependent Variable 

The estimated speed given by the participant (measured in miles per hour). 

All participants were shown the same seven film clips of different traffic accidents which were originally made as part of a driver safety film.

 After each clip participants were given a questionnaire which asked them firstly to describe the accident and then answer a series of questions about the accident.

The independent variable 

 The wording on a question in a questionnaire: One group was asked, “About how fast were the cars going when they smashed into each other?”  A second group was asked, “About how fast were the cars going when they hit each other?”  A third group was not asked about speed. One week later, all participants were asked to complete another questionnaire which contained the critical question, “Did you see any broken glass?”

The Dependent Variable

Yes or no to the question "Did you see any broken glass"? 

Participants were shown a 1 minute video clip that contained a 4 second multiple car crash. They were then given a questionnaire.  There was a critical question about speed: One group was asked, “About how fast were the cars going when they smashed into each other?” Another group was asked, “About how fast were the cars going when they hit each other?” The third group did not have a question about vehicular speed. A week later,  participants completed another questionnaire asking, “Did you see any broken glass  Yes/No?” There had been no broken glass in the original film.