Loftus and Palmer

Lotus and Palmer study, used in Cognitive Psychology

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Loftus and Palmer

Background:

Memory- Short term and Long term
- Semantic memories
- Schema theories - having a pre-expectation of how a situation should occur and what should happen in that situation e.g. going out for a meal, car accidents.

Eyewitness Testimony:

According to Brown (1986) judges, defence attorney's and psychologists believe that eyewitness testimony is the least trustworthy kind of evidence for guilt, whereas jurors have always found it more persuasive than any other form of evidence.

It is deemed unreliable because people tend to 'fill in the gaps' in their memory on the basis of what they think might have happened.
Real events are more likely to interfer with recall of other events.

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EWT

EWT is unreliable because:

  • recall is limited
  • can be biased, include elaboration and be inaccurate
  • past events can cause interference
  • media influences
  • expectations can alter memory
  • emotions can alter what is perceived
  • past experiences (schemas) can alter memory

Loftus and Ketcham discovered that in 1991 someone was sentence to a death penelty in the US due to an eye witness testimony.

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Exp 1

Loftus and Palmer split their study up into 2 lab experiments.

Exp 1 Aim: To investigation the effect of leading questions.

Procedure: - 45 students watched film clips of car accidents and were then asked to do 2 things:

1. Write an account about what they had seen,

2. Answer questions about what they had seen.

A critical question was amongst these questions:

About how fast were the cars going when they (verb) each other?

There were five conditions (verbs/IVs) in the experiment and five groups of students.

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Results

Verbs:

Contacted (Can) = 31.8 mph

Hit (Hedgehogs) = 34.0mph

Bumped (Build) = 38.1mph

Collided (Chocolate) = 39.3mph

Smashed (Sandcastles) = 40.8mph

Estimates were higher for the more severe sounding verb.

IV = verb used

DV = estimates given

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Exp 2

Exp 2

Aim: To see if the effects from exp 1 were due to distortion of memory.

Procedure: 150 students were shown a 4 second multiple car accident in a 1 minute film. After this film, the students were divided up into 3 experimental groups.

Group 1 - How fast were the cars going when they HIT each other?

Group 2 - How fast were the cars going when they SMASHED into each other?

Group 3 - Asked no questions about the speed of the cars.

One week later the participants were asked more questions: -

Did you see any broken glass?

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Results

Did you see any broken glass?

Group 1 (HIT) - Yes = 7 No = 43

Group 2 (Smashed) - Yes = 16 No = 34

Group 3 (Control) - Yes = 6 No = 44

IV = Verb used

DV = whether the Pp's saw broken glass or not

Conclusions that can be drawn - Schemas affect our responses

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conclusions

Loftus and Palmer concluded that there are two types of information which can make-up memory of an event.

1. The information we get from perceiving the event

2. The information we get after the event.

Loftus and Palmer concluded that the leading questions actually altered peoples' memories and that expectations of an accident interfere with memories of the actual event - Schema theory.

How representative were the sample?

  • Students can have better memories than older people
  • Not experienced drivers therefore can find it harder to estimate speeds
  • Students could produce demand characteristics
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