EyeWitness Testimony

outline of EWT,  the influence of anxiety on EWT, influence of age on EWT

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  • Created by: Lauren
  • Created on: 08-04-12 15:14

Outline of EWT

  • The human memory is constantly updating itself- stored material is reorganised and transformed because of new knowledge  and the passage of time. New info is put into the right format for storage but memories can be modified and changed as they are encoded.
  • Cognitive psychologists agree that most memories are in part reconstructions of events, rather than exact versions. It seems that when we remember something instead if replaying a completely accurate version of an event in our head, we remember some accurate fragments then sub- consciously fill in the rest with common sense and logic.
  • Our expectations also play a big role, causing us to memorise and recall things as we expect them to be and not always as they actually were.
  • Loftus (2003) said that 'memories are the sum of what people have thought, what they have been told and what they believe'.
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Key Study- Loftus & Palmer (1974) 1

  • They wanted to find out whether memory could be influenced by the type of question people were asked (leading questions). They conducted 2 experiments:
  • Experiment 1: 45 students were shown a series of car crash videos. The students then had to fill in a questionnaire. One of the questions was "how far were the cars travelling when they smashed/ collided/ bumped/ hit/ contacted into each other". There were 5 groups and each group had a different verb.
  • The verb placed at the end of the sentence made a huge difference to the estimated speed of the cars. To conclude, info presented after an event can significantly influence our perception of that event. Loftus and Palmer thought that this alteration could be either distortion (where the memory of the video was changed) or response bias (where the word influenced a judgement).
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Key Study- Loftus & Palmer (1974) 2

  • Eperiment 2: 150 students were shown the videos and then were presented with a questionnaire. Some had the question about the car crashing with eaither the verb hit or smashed. Others didn;t have the question. A week later they were asked if they saw any broken glass (there was no broken glass in the video).
  • 32% of smashed group saw broken glass, 14% of hit group and 12% of control group. 
  • Questions following an event can influence memory. Using the word 'smashed' builds the concept of broken glass in memory.
  • This supports the reconstructive memory hypothesis where information retained at the time of an event can be altered or influenced in some way by information presented after the event. Once this information is linked together, it is difficult/ impossible to seperate it.  
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Evaluation of Loftus and Palmer

  • Very reliable- no extraneous variables as it was a lab experiment and it was very well controlled.
  • Lacks ecological validity as it isn't high in mundane realism- the p's saw videos not real crashes.
  • Possible demand characteristics.
  • University students- not generalisable to whole population as students tend to be clever and can possibly remember things better. Thus do not demonstrate the whole population.
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Other Research Support

  • Miller (2000)- Ronnie Bullock, Edward Honaker and Kirk Bloodsworth were all convicted wrongly of deadly crimes because of inaccurate EWT. DNA tests later proved that someone else was responsible for their crimes.
  • Cutler and Penrod (1995) estimate that as many as 4500 people are wrongly convicted in the US each year because of faulty EWT
  • Real life reports are high in mundane realism.
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Influence of Anxiety on EWT

  • Anxiety can be caused through witnessing a distressing event i.e. either being a victim or feeling empathy for a victim or giving evidence of that event because it is a serious presuured situation.
  • It has been established that high levels of anxiety can impair the ability to both encode and retrieve memories, this has implications for EWT.
  • Peters (1988) conducted a study in a health clinic where people received inoculations (anxiety- causing event). They spent equal amount of time with a nurse who gave the injection and a researcher for a brief. 1 week later that p's had to identify the nurse and researcher from a series of photographs. It was found that the researcher was more readily recognised than the nurse. It was suggested by Peters that the anxiety of the injection directly affected the accuracy of memory it has also been suggested that the needle on the syringe drew attention away from the nurse and other surroundings. This indicates that witnesses of a crime may be distracted by a particular aspect of the crime, especially things that could be seen as a weapon.
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More Supporting Research on the Influence of Anxie

  • Loftus et al (1987) monitored the gaze of p's and found they focused on the gun in a robbery and couldn't identify the robber when questioned later. This is in comparison to similar p's who saw the same video withou a gun and could recall much more. This is know as 'weapons- focus'.
  • The violece of an event can also be a cause for anxiety. Loftus and Burns (1982) made p's watch a film of a crime. Some p's saw a version with a young boy being shot in the face (unethical- p's psychological distress). When questioned about events in the film, the p's that saw the less violen version recalled much more than those with the violent version. It seemed that the shock of the event disrupted storage of other details, both before and after the violent scene.
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Non- Supportive Evidence

  • Mitchell et al (1998) suggested that rather than being threatening and anxiety- inducing, the presence of a weapon is just unusual and is seen as a novelty.
  • All other findings are based on artificial experiments. Yuille and Cutshall (1986) found some contradictory evidence in their naturalistic experiment. The interviewed 13 witnesses of a real- life shooting incident in which someone was killed. Despite the anxiety caused, the accuracy of recall wasn't significantly affected.The witnesses were resistant to leading questions and there was little evidence of memory reconstruction.
  • The influence of anxiety on memory could be said to follow the Yerkes- Dodson law. This suggests that there may be an ideal of optimum point at which anxiety actually helps memory but above or below this optimum, anxiety causes more harm than good.  
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Influence of Age on EWT- Children

  • The younger the child, the less information they provide spontaneously. Because of this, interviewers have to encourage the child to give more detailed or specific responses. Unfortunatly the danger of this is that the child is likely to be influenced by cognitive factors (the way questions are asked effects how they are answered) and social factors (power and status of authoritive adult).
  • Suggstibility- children are more sensitive to leading questions. Ceci et al (2000) found in children aged 3-12 years and especially 3 and 4 year olds were most susceptable to having their memories altered by leading questions. Warren et al (2005)  gave children and adults a story to read then asked 20 questions, 15 of which were misleading. Children were more likely to be influenced.
  • Language abilities- a child's ability to comprehend and answer questions will effect recall. Goodman and Schaaf (1997) found that the more complex a question, the more likely a child was to give an inaccurate answer.
  • Memory processes- younger children recall less complex memories. Saywitz (1987) asked children in her study to listen to a description of a crime. They then had to recall it immediatley and then again 5 days later. The younger children (aged 8) were less detailed but just as accurate than the older ones (11 and 15) but had a tendancy to embelish more,
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Influence of Age on EWT- The Elderly

  • The elderly are also susceptable to leading questions.
  • Cohen and Falkner (1989) young adults (average 35 yrs) and elderly p's (average 70 yrs) were shown a silent film- clip of a kid- napping. 10 mins later the p's were given one of two versions of a written account of the crim. one was accurate, while the other was inaccurate. Later all p's were tested for their memory of the event. It was found that elderly p's were more likely to be influenced by the incorrect info .
  • It is not supported by Coxon and Valentine (1997). In their study p's were shown a video recording of a staged crime. Both young children and the elderly were l;ess accurate in their accounts that young adults. C & V put this down to immature cognitive development in children and advancing age in the elderly. However, whilst children were found to be more suggestible to leading questions, the elderly were found to be no more suggestible than the young adults. They concluded that testimonies from the elderly were less reliable but this is due to less complete recall rather than increased susceptibilty to leading questions.
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Comments

Aks

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Very useful thankyou :)

Lauren

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ooh good, thanks :)

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