Salvador Dali's the Persistence of Memory



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Short Term Memory
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Eye Witness Testimony
Leading Questions and Factors Affecting EWT
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Improving Memory

Eye witness testimony (EWT)

…and factors affecting the accuracy of EWT, including anxiety, age of witness. 

Introductory comments

This little bit is aimed at giving you some idea of how influential EWT can be in convicting alleged criminals. 

The Devlin Report (1976) investigated the accuracy and importance of EWT following some serious miscarriages of justice.  The report examined over 2000 identity parades in England and Wales in 1973 and followed them through to their outcomes in court. 

Of the 2000 parades 45% (900) resulted in a suspect being identified and out of these 900 82% were convicted of the crime.  In over 300 cases the EWT was the ONLY evidence provided and 74% of these were convicted!

Although juries love EWT (and so do the police), both placing a lot of trust in it, EWT may not be as accurate as the witnesses and the police like to think.  Fruzzetti et al 1992 concluded that thousands of people are convicted each year on the basis of inaccurate EWT and Wells et al (1998) investigated 40 American cases were people convicted by EWT were later acquitted by DNA evidence. 

Loftus (1974) highlighted this effect!  She got participants to act as jurors and decide the guilt or innocence of role playing thieves.  When evidence was merely circumstantial such as the suspect being seen entering the building where the crime took place only 18% were judged to be guilty.  However, when the testimony of an eyewitness was added who claimed to have seen the defendant commit the crime, this rose to 72%!!.  Even when the witness admitted that their eyesight was poor and that they were not wearing glasses at the time, 68% of jurors were still prepared to convict on their testimony alone!



In a classic American study carried out by Buckhout 1980, a 13 second film clip of a mugging was shown on TV.  An identity parade of six suspects was later shown and viewers asked to phone in and say who they thought had dunnit! 

Given that there were only six suspects, chance alone would suggest that 17% would get it right!  In fact only 14% identified the person correctly suggesting that EWT is not particularly accurate in some cases!  I will regale you with my own anecdotal evidence in class!!! (Something to look forward to there lol)!

Reconstructive nature of memory

The main models of memory, such as multistore, see memory has the storage of information in a fixed form that does not change over time.  So that a memory of falling off of your bike at the age of 6 and who helped, how much blood was spilt etc.  will be the same in 10 years time as it is today and as it was a few days after the event.   However, reconstructive theories believe memory to be flexible and constantly being altered in the light of our experience and with constant retelling.


Schemas are packages of knowledge (according to Cardwell),  that we acquire through experience.  They help us to build up a picture of our World and enable us to make predictions about our day to day lives.   For example we will have a schema for funerals, so that when we are in the unfortunate position of attending one we are able to behave in accordance with social norms without having to read up on them first.  Our schema for funeral will exist even if we have never been to a funeral before, because we will have read about them, heard about them and seen them portrayed in soaps etc.  Similarly we will have schemas for going to weddings, restaurants, for sitting exams, going clubbing, romantic dates etc.  Imagine going on your first date with nor prior expectations of what is involved!!! 

Cohen (1993) suggested a number of ways in which schemas affect our memory.

1.       Selection: Information that does not fit current schemas is ignored.

2.       Abstraction: we are inclined to recall the overall gist and forget the detail.

3.       Interpretation: schemas provide existing knowledge to help us understand novel situations.

4.       Normalisation: memories are distorted to fit with our existing expectations.

5.       Retrieval: schemas (or schemata) help us fill gaps in our memory by making a best guess.

Think how some of these would tie in with reconstructing the scene of a crime!  For example, evidence suggests that minor details are not remembered accurately but are added later in line with what we would expect to have happened.

Other examples of research into schemas

Brewer & Treyens (1981) got participants to wait one a t a time in a room for 35 seconds.  The room looked like an office and contained 61 items.  Most objects were ones you would expect to be in an office, others such as a skull, a brick and a pair of pliers, were not.  Later they were asked to recall the items in the office.   


Not surprisingly participants were most likely to recall the typical office fare, desk, chair etc.  Most of the errors were substitutions, i.e. people tended to include items such as pens and telephones that would be in the ‘schema for office’, but in this case weren’t.


Participants were using their schema for ‘office’ to fill in the gaps in their memory. 

Note:  this is a favourite experiment for A2 coursework!


Many of the participants recalled the skull, presumably not in most peoples’ schema for an office!  Schema plus tag theory attempts to explain this.  The idea being that we store our memory of the office with our schema for office, but attach a marker (or tag) to indicate any unexpected aspect.  For a topical example, peoples’ memories of Manchester United games may all seem pretty much the same and if asked to describe one 3 weeks ago you may struggle and have to rely on your schema for football to fill in the gaps.  However, if something out of the ordinary occurred such as United winning or not conceding a goal, then that will be tagged onto the memory and you will be better able to recall the details of the match.  (Important note, do not use this has an example.  We all know how many MUFC fans there are out there, including examiners!).



Work in a similar way to schemas but concern people and our prejudices.  Main studies include

Allport & Postman (1947) who showed participants pictures of a white man with a razor threatening a black man on the subway.  Later, participants tended to recall the black man threatening the white. 

Cohen (1981) showed participants a video of a couple eating a meal.  They were told that either the woman was a waitress or a librarian.  This information later influenced the participants’ description of the woman.  I’ll leave their descriptions to your own stereotypical views.  (note:  the stereotype was more obvious if participants were told the person’s occupation after watching the video).

Summary of schemas and stereotypes

The theory suggests that we are only able to take in so much information at the scene of a crime or incident.  At a later date when we are asked to provide greater detail then we rely on past experience (schemas) and prejudices (stereotypes) to fill in the gaps.  We use expectations to reconstruct our memory.


The theory over emphasises the inaccuracy of our memory.

Schema theory provides no explanation of how schemas work.

Research into schemas:  Bartlett’s War of the Ghosts (1932)  

Bartlett’s theory was unfashionable for many years but has recently been recognised as providing a valuable insight into the reconstructive nature of human memory.  His theory was based on Western recall of a native North American folk story.  He suggested that we make the following alterations in such cases:

·         Rationalisations: people tended to add material to justify parts of the story.

·         Omissions: parts of the story, particularly those difficult to understand, were left out.

·         Changes of order:  the storyline was rearranged in an attempt to make sense out of it.

·         Distortions of emotion: people added their own feelings and attitudes to the story.


 Mind Changers: Sir Frederic Bartlett


The War of the Ghosts

One night two young men from Egulac went down to the river to hunt seals and while they were there it became foggy and calm. Then they heard war-cries, and they thought: "Maybe this is a war-party". They escaped to the shore, and hid behind a log. Now canoes came up, and they heard the noise of paddles, and saw one canoe coming up to them. There were five men in the canoe, and they said:

"What do you think? We wish to take you along. We are going up the river to make war on the people."

One of the young men said,"I have no arrows."   

 "Arrows are in the canoe," they said.

"I will not go along. I might be killed. My relatives do not know where I have gone. But you," he said, turning to the other, "may go with them."

So one of the young men went, but the other returned home.    And the warriors went on up the river to a town on the other side of Kalama. The people came down to the water and they began to fight, and many were killed. But presently the young man heard one of the warriors say, "Quick, let us go home: that Indian has been hit." Now he thought: "Oh, they are ghosts." He did not feel sick, but they said he had been shot.

So the canoes went back to Egulac and the young man went ashore to his house and made a fire. And he told everybody and said: "Behold I accompanied the ghosts, and we went to fight. Many of our fellows were killed, and many of those who attacked us were killed. They said I was hit, and I did not feel sick."

He told it all, and then he became quiet. When the sun rose he fell down. Something black came out of his mouth. His face became contorted. The people jumped up and cried.      He was dead.

(from Bartlett, Remembering, 1932/1995, p. 65)

Being a native North American story the narrative contains words, concepts and ideas different to ones that as Westerners we are used to.    As a result when we are asked to retell the story we make alterations.  These are based on our own schemas, stereotypes and expectations.  

Look at the list of alterations Bartlett suggested (previous page) and try to spot examples of them in the participant’s version below:

War of the Ghosts: sample recall

Two men from Edulac went fishing. While thus occupied by the river they heard a noise in the distance.

"It sounds like a cry", said one, and presently there appeared some men in canoes who invited them to join the party on their adventure. One of the young men refused to go, on the ground of family ties, but he other offered to go.     

"But there are no arrows", he said.

"The arrows are in the boat", was the reply.

He thereupon took his place, while his friend returned home. The party paddled up the river to Kaloma, and began to land on the banks of the river. The enemy came rushing upon them, and some sharp fighting ensued. Presently some one was injured, and the cry was raised that the enemy were ghosts.

The party returned down the stream, and the young man arrived home feeling none the worse for is experience. The next morning at dawn he endeavoured to recount his adventures. While he was talking something black issued from his mouth. Suddenly he uttered a cry and fell down. His friends gathered round him.

But he was dead.

(from Bartlett, Remembering, 1932/1995, p. 66 -- transcript of a recall protocol taken after 20 hours)    

The story above is by way of illustration.  There is no need to learn the detail, only what it tells us!

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