Chapter 7

Memory Errors

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The Seven ‘Sins” of Memory

• Transience

• Absentmindedness

• Blocking

• Source Misattribution

• Suggestibility

• Bias

• Persistence

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Read the following;

‘When the man entered the kitchen, he slipped on a wet spot and dropped the delicate glass pitcher on the floor. The pitcher was very expensive and everyone watched the event with horror.’

(Bransford, 1979)

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The big question…

Did anybody write about the glass being broken or smashed?

This is not in the original paragraph but the sentences imply that it occurred.

Past experience has distorted the actual memory.

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The Constructive Approach

Bartlett (1932) proposed the constructive approach. He stated memory is not necessarily an accurate account of the experienced event. Existing knowledge (schemas) are used to understand the new information. Memories are automatically changed to fit in with what we already know.

We tend to see and in particular interpret and recall what we see according to what we expect and assume is 'normal' in a given situation.

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The War of the Ghosts (Bartlett, 1932)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 outer 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. Chp 7

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Bartlett’s “ War of the ghosts ” Experiment

British psychologist Fredrick Bartlett

• Participants read the story taken from Canadian Native Folklore

• Bartlett asked them to recall it as accurately as possible

• The same participants came back a number of times to try to remember the story at longer and longer intervals after they first read it.

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Example: Reproduction 10 The War of this Ghosts

Two Indians were out fishing for seals in the Bay of Manpapan, when along came five other Indians in a war-canoe. The y were going fighting. "Come with us," said the five to the two, "and fight." "I cannot come," was the answer of the one, "for I have an old m other at home who is dependent upon m e." The other also said he could no t come, because he had no arm s. "That is no difficulty" the others replied, "for we have plenty in the canoe with us"; s o he got into the canoe and wen t with them. In a fight soon afterwards this Indian received a mortal wound. Finding that his hour was co m e, he cried out that he was about to die. " Nonsense," said one of the others, "you will not die." But he did.

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Bartlett’s “ War of the ghosts ” experiment

The errors Bartlett’s participants made:

• Forgot much of the information in the story

• Most participants’ reproductions of the story

– were shorter than the original

– contained many omissions

– inaccuracies

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Bartlett’s Analysis of the Changes

The story became shorter and more coherent.“No trace of an odd, or supernatural element is left: we have a perfectly straightforward story of a fight and a death.”

Achieved by: • Omissions: ghosts omitted early; the wound became a

matter of flesh, not spirit• Rationalization: growing coherence among parts • Transformation of details into more familiar ones.

Canoes Boats

• Changing order of events

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The changes that occurred in the remembered stories tended to reflect the participants’ own culture

• Constructive memory– Constructive processes that influence memory

during encoding

• Reconstructive memory– ….During retrieval

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Bransord and Johnson (1972)

If the balloons popped, the sound wouldn’t be able to carry since everything would be too far away from the correct floor. A closed window would also prevent the sound from carrying, since most buildings tend to be well insulated. Since the whole operation depends on a steady flow of electricity, a break in the middle of the wire would also cause problems. Of course, the fellow could shout, but the human voice is not loud enough to carry that far. An additional problem is that a string could break on the instrument. Then there could be no accompaniment to the message. It is clear that the best situation would involve less distance. Then there would be fewer potential problems. With face to face contact, the least number of things could go wrong. (p. 719)

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Doesn’t make much sense, does it? Some of the participants got just this paragraph, and they didn’t think it made much sense either. They also couldn’t remember it very well. Another group of participants saw this picture beforereading the paragraph.

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Suddenly the paragraph makes sense, right? The participants were also able to remember it pretty well.

Another group of participants saw the same picture after reading the paragraph, and a fourth group saw only part of the picture beforereading the paragraph, with enough missing to make it difficult to tell what the picture was about. Neither of these groups could make much sense of the paragraph, and they didn’t remember much of it either.

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Schemata and Scripts

General knowledge structure for an event or situation. Developed over repeated similar experiences.

When we encode a new experience into memory, we first activate a schema, which selects which aspects of the experience we encode.

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• These schemas are abstract, because they’re used to encode a bunch of related experiences that may have different specific properties but the same overall structure. When schemas are selecting information to encode, they get rid of the specific details of the new experience.

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The new experience is integrated into the schema, and structural details that are new and relevant to the schema can be added to it, allowing the schema to handle an even wider range of experiences.

Finally, the experience is interpreted through the schema, so that information in the schema but not immediately apparent in the experience can be inferred.

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Fast Food Schema

Say you walk into Culver’s. You automatically activate your Culver’s schema, which tells you things like how to order (at the counter), that they will bring your food to the table, that they give you a cup and you get your own drink from the soda fountain, etc. If you’re later asked to remember your trip to Culver’s, you’ll likely remember all of these things, and forget all the incidental details of the visit. That’s selection and abstraction.

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If you find that they no longer give you a cup, but instead fill your cup for you, you’ll probably stick that into your schema (especially if it happens on a couple visits). That’s integration.

If instead you walk up to the counter, order your food, and then receive your food without getting a cup, you’ll ask for one, because you know you should get a cup so you can get your own drink. That’s interpretation.

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Schema Based Errors in Laboratory Research

DRM (Dees, 1950; Roediger & McDermont, 1995) paradigm. Word-list procedure that induces schema based false memories.

Video Alda and Schactner (begin at 5:30)

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DRM Procedure Findings

• Effects both recall and recognition

• Lists showed serial position effects (see text pg. 133). Memory for the Critical lure (false memory) was included in list at a rate of middle items on the list (60%).

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Update on Textbook

While your text states that “electrophysical brain activity is similar for true and false recognition of words” more recent studies do find differences:

Using PET and auditory study conditions, Schacter, Reiman, et al. (1996) found that true recognition was more likely than false recognition to elicit activity in auditory-specific regions of the cortex (see Video on slide 19) and using fMRI and visual study conditions, Cabeza, Rao, et al.(2001) found that true recognition was more likely than false recognition to elicit activity in cortex areas related to visual processing

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Why does DRM produce false memories?

1) Schema activation at both encoding and at recall.

2) Fuzzy Trace Theory- at presentation a “gist” of the list becomes activated. At recall the gist becomes reactivated but the details are not available.

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Eyewitness Memory Studies

Misinformation Effect – people have false memories for an event based on suggestive information provided by others.

Post-event Information can effect people’s recall of a witnessed event.

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GP Mem(1)

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Participants watched a video of

a car crash. They were then

interview about their recall.

Participants were asked the

following question with

different verbs used to fill in the blank.

About how fast were the cars going when they

___________ with each other?

GP Mem(1)

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Post-event information effected speed estimates.

Speed estimates for each verb

VerbMean speed estimate (mph)

Smashed 40.8

Collided 39.3

Bumped 38.1

Hit 34.0

Contacted 31.8

Those who got the verb “smashed” reported having seen broken glass more often (32%) than did participants in the “hit” condition.

Loftus & Palmer, 1975

Other studies have found that suggestive post-event

information can change recall of a stop sign to a

yield sign.

“How fast was the red car going when it went past the yield sign?”

Stark, Okada & Loftus, 2010

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Explanation

Source Misattribution – participants misattribute the post-event information to their memory the event rather than the interviewer.

Lindsay (2010) – slides of a robbery were presented with a voice-over narrative (female voice). Two days later heard a narrative again (without slides) that included false information given in either the same female voice, or in a male voice.

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Results

When the source of the information is more distinguishable from the event, less misattribution errors were made.

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Memory and EyewitnessIdentification

Unconscious Transfer

An eyewitness associates a familiar person “Bystander” with a crime performed by someone else. The eyewitness may correctly remember having seen both the person and the crime but may have incorrectly associated the innocent person with the crime.

Unconscious Transference:

Ross et al. (1994)

Eyewitnesses were three times more likely

to select an innocent bystander from a

lineup than a stranger.

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Australian eyewitness expert Donald Thomson appeared on a live TV discussion about the unreliability of eyewitness memory. He was later arrested, placed in a lineup and identified by a victim as the man who had raped her. The police charged Thomson although the rape had occurred at the time he was on TV. They dismissed his alibi that he was in plain view of a TV audience and in the company of the other discussants, including an assistant commissioner of police. Eventually, the investigators discovered that the rapist had attacked the woman as she was watching TV - the very program on which Thompson had appeared. Authorities eventually cleared Thomson. The woman had confused he rapist's face with the face the she had seen on TV.

Bobby Poole and Ronald Cotton

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When Jennifer Thompson was asked to identify her perpetrator from a series of photographs, she was told by officers that she should not feel compelled to make an identification.

However, Jennifer’s faith in the legal system led her to believe that the police must have had a suspect to warrant her participation in photographic identification. And when Jennifer selected the photo of Ronald, the police told her she did great.

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After viewing the lineup for a while, she (Jennifer) told detectives she was deciding between Nos. 4 and 5. Detective Gauldin asked whether she would like the lineup repeated. She said yes. She then stated that Cotton "looks the most like him."

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Eighteen people had been sentenced to death before DNA proved their innocence and led to their release.

The average sentence served by DNA exonerees has been 13.6 years.

In almost 50 percent of DNA exoneration cases, the actual perpetrator has been identified by DNA testing.

Something to Think About

About seventy-five thousand police lineups take place every year. Statistics show that between 20% and 25% of the time the eyewitness identifies a suspect in the lineup that the police know isn’t correct. So upwards of 25 out of 100 people are falsely identified by the victim as the suspect in a crime we know they didn’t commit. In experimental studies where people are exposed to mock crimes the eyewitnesses tend to do exactly what Jennifer Thompson did: even though the real suspect isn’t in the lineup they finger someone who best resembles who they remember. Source

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Loftus (1973) recorded verdicts in a mock trial. Two separate sets of the jurors heard evidence differing only by the presence or absence of an eyewitness. With no eyewitness, only 18% of jurors gave guilty verdicts. Addition of an eyewitness identification increased the proportion of guilty verdicts to 72%.

More!

Even when the identification was impeached, the guilty rate was still 68%.

Several other studies have similarly found that juries tend to base their decision on a confident eyewitness identification even when other factors (such as poor visibility or bias) question its validity.

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Innocence ProjectEyewitness misidentification is the greatest contributing factor to wrongful convictions proven by DNA testing, playing a role in more than 70% of convictions overturned through DNA testing nationwide.

Applications of Eyewitness Memory Research

• Double Blind Line-up Procedures

• Warning Witnesses that the participant may or may not be present.

• Line-ups include similar looking people.

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• Sequential Line-ups

For sequential lineups, witnesses must exercise "absolute judgment," comparing each photograph or person only to their memory of what the offender looked like.

In simultaneous lineups, witnesses must use "relative judgment" to compare lineup photographs or members to each other.

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The cognitive interview has four main techniques: Gieselman et al. (1986)

1. Report everything.

Witnesses may omit details they feel are irrelevant, especially if they do not fit into their existing schemas for that type of event. Encouraging them to report every detail, no matter how small, can increase witness accuracy.

2. Reinstate the context at the time of the event.

Encouraging witnesses to recall how they felt, the weather, smells, time of day etc. This helps put the witness back to the time of the incident and may improve recall accuracy.

3. Change perspective. Trying to adopt the viewpoint of a different witness, e.g. a prominent character in the incident, can encourage recall of events that may otherwise be omitted.

4. Change the order in which the event is recalled. Recalling events in reverse order, or from the middle and working backwards and forwards in time, can interrupt schema activation, make it harder for the witness to reconstruct a story that makes sense, and improve eyewitness accuracy.

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Research and the Cognitive Interview

Memon (2010) meta-analysis – Increase in correct details, small increase in incorrect

details.– Most effective for older eyewitnesses.

Compo et al. (2012) – South Florida- police were not properly using the techniques.

“Of participants who reported receiving academy training after the National Institute of Justice guidelines were released, only 14.6% indicated that their interview training was based on those guidelines.” Learn More Could be on exam.

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