Key Issue EWT + Maas and Kohnken (1989)

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Key issue: Reliability of EWT

Importance of EWT

EWT is an important area of study in cognitive psychology and memory studies. It is used as evidence in trials globally. Juries tend to pay extra attention to EWT and see them as trustworthy, reliable and convincing. However, research has shown that EWT can be influenced by many psychological factors.

I. Reconstructive memory (resulting in errors)

II. Leading Questions

III. Anxiety and Stress

IV. Weapon Focus [Maas and Kohnken (1989)]

I. Reconstructive Memory (resulting in errors)

Human memory does not store information exactly as it was presented to us - our memory does not work like a video tape!

We gather information as far as getting the 'gist' of things or their underlying meanings. Then we make sense of the information and try to fit them into schemas. Schemas allow us to make sense of what we encounter so that we can predict what is going to happen and what we should do.


Schemas are effective since they remove the need to store similar nformation more than once. Schema driven processing increases the efficiency or cognitive economy with which memory operates. However, some schemas may have consequences for the way we store information. By forcing new situations to fit into existing schemas, we might distort them in some way. This means that out stored memory nay not be exactly the same as what we experienced. When we later recall this information distortions will have been incorporated into our recall and will not be accurate.

Bartlett (1932)

Bartlett tested the idea of schemas using a variety of illustrations and stories to show that memory is an active process and subject to individual interpretation and construction.

In his famous study 'War of Ghosts' Bartlett asked Britsh participants to memorise a short story about Native American traditions. This story was very different from conventional European stories, so the participants would not have schemas to help them make sense of the story.

Bartlett depicted the story and predicted that it would become distorted in 4 ways. 

1. the story became shorter, 2. detail would be lost, 3. some details would be changed (e.g. seal hunting was recalled as fishing), 4. structure was altered to become more 'westernised'

see also: Loftus & Palmer (key study)

II. Leading Questions

A leading question is a question that contains information previously unknown to the witness. They pose many problems in criminal proceedings because many police and lawyers ask them (even subtly) and this information could have the potential to change the witness' understanding of the event. Later, when asked about the incident, that information may have become implanted in their recollection of what happened.



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