+

Chapter 14

Eyewitness Testimony

+Change Blindness

Simons and Levin (1998)

Design:

A stranger asks unwitting participants for directions

After 10–15 seconds, people carrying a door pass in front of the participant, blocking their view

During this time the stranger is replaced by a different person

Results:

About 50% of participants failed to notice the switch!

Change blindness:

Failing to notice apparently obvious changes in a scene

Levin et al. (2002)

Change blindness blindness:

The unduly optimistic belief

that one is very rarely

affected by change

blindness

People underestimate the

importance of fixating in order to

detect changes

They mistakenly assume that

they fully process everything in

the periphery, too

http://www.youtube.com/watch?v=c48Ol9xkaqM

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+Some Factors Reducing the

Accuracy of Eyewitness Testimony

Eyewitnesses generally are

taken off guard by the crime

They are often preoccupied

with their own thoughts and

plans

The criminal actions are often

brief and swift

Criminals take steps to avoid

recognition

e.g. they wear disguises

Eyewitnesses are subject to:

Change blindness

Prior expectations

Pre/post-event information

Overblown confidence

Unconscious transference

Verbal overshadowing

Weapon focus

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+Expectations Can Distort Memory

Hastorf and Cantril (1954)

Design:

Dartmouth and Princeton students watched an American football

game between the two schools

They were asked to detect violations of rules

Results:

Princeton students detected twice as many violations by

Dartmouth than did Dartmouth

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+Schemas for Bank Robbery

The schema for a

bank robber is:

male, wearing a

disguise and dark

clothes, making

demands for

money, with a get-

away car and

driver.

+Expectations Can Distort Memory

Lindholm and Christianson (1998)

Design:

Swedish and immigrant students watched a simulated robbery, in which a knife-wielding burglar was either:

Swedish

An immigrant

The students were asked to to pick the perpetrator from a lineup:

Half were Swedish (4); half were immigrants (4)

Results:

The correct person was identified 30% of the time.

Both Swedish and immigrant students were twice as likely to mistakenly select an innocent immigrant as an innocent Swede

Conclusion:

The overrepresentation of immigrants in Swedish crime statistics likely influenced participants’ expectations

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+Schemas Shape and Distort

Memory

Bartlett (1932)

Schemas structure our world

knowledge and influence

memory storage/retrieval

Contribute to memory

reconstruction:

Used to piece together

the details of an event in

terms of “what must

have been true”

Eyewitnesses use schematic

information to assist in their recall

Tuckey and Brewer (2003a;b)

Eyewitnesses have better recall

for schema-relevant information

than for irrelevant information.

Eyewitnesses generally

interpreted ambiguous

information in a way that made

it consistent with the schema.

Balaclava wearer was male.

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+Schema Intrusions Increase with

Ambiguous Stimuli

Mean correct responses and schema-consistent intrusions in the ambiguous and unambiguous conditions with cued recall. Data from Tuckey and Brewer (2003b).

+Leading Questions

Loftus and Palmer (1974)

Design:

Participants watched a multiple-car accident and described what happened

Then answered specific questions:

“How fast were the cars going when the cars smashed into/hit/collided with/bumped/contacted each other?”

After one week, they were asked if they saw broken glass

(There wasn’t any)

Results:

Speed estimates depended on the word used in the question

Highest for “smashed” -- 40.8 mph

Lowest with “contacted” -- 31.8 mph

When “smashed” was used, participants were more likely to mistakenly claim they saw broken glass (32% compared to 14% for “contacted”)

Conclusion:

Memory can be systematically distorted by the way questions are phrased

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+Interference and Memory Distortion

Eakin, Schreiber, and Sergent-Marshall (2003)

Eyewitness memory can be impaired by misleading information presented after they have witnessed the crime.

This is an example of retroactive interference

Memory is impaired even when eyewitnesses were warned about the presence of misleading information after it had been presented.

Example – maintenance man repairing a chair steals money and a calculator.

Lindsay et al. (2004)

Design:

Listened to a thematically similar or dissimilar narrative prior to seeing a burglary

Results:

Recall errors were more frequent when the prior narrative was similar to the actual event

This is an example of proactive interference

Conclusion:

Eyewitnesses’ previous experiences can shape what they remember

Example – visit to palace vs palace burglary.

Retroactive Interference Proactive Interference

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+Explaining Retroactive Interference

Distortion

The Source Monitoring Framework

A memory probe activates related traces

Including memories from other sources

One tries to determine the source, based on the information

the memory contains

Sometimes source misattributions occur

Especially likely when memories from different sources

are similar

Source Monitoring Framework

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+A Recent Source Misattribution

"I remember landing under sniper fire," she said in Washington on

Monday. "There was supposed to be some kind of a greeting

ceremony at the airport, but instead we just ran with our heads

down to get into the vehicles to get to our base."

News footage of the event however showed her claims to have been

wide of the mark, and reporters who accompanied her stated that

there was no sniper fire. Her account was ridiculed by ABC News as

"like a scene from Saving Private Ryan".

http://www.youtube.com/watch?v=8BfNqhV5hg4

Is this motivated political opportunism or was the original

memory distorted by viewing other sources of information?

Hillary Clinton in Sarajevo, 1996

+Explaining Retroactive Interference

Distortion

Loftus (1979)

Design:

Witnessed a pedestrian accident with a car stopping at either a:

Stop sign

Yield sign

Two days later, participants were asked a leading question, referring to the opposite type of sign to the one they had seen (stop vs yield).

Forced-choice recognition test for snapshots from the original scene

One photo had a yield sign; the other had a stop sign

Results:

70–85% selected the sign they were falsely led to believe existed.

This happened even when subjects were paid for correct answers to reduce demand characteristics.

Conclusion:

Information from misleading questions permanently alters the original memory, which is overwritten and destroyed.

Overwriting the Original Memories

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+Misinformation Effect: Caveats

Bekerian and Bowers (1983)

Misinformation effects can be eliminated by systematically questioning participants in order -- from earlier incidents to later ones

This suggests that the original memory trace survives.

Loftus (1992) revised her view to say that eyewitnesses can come to accept misleading information as time goes by.

The original memory need not be overwritten but added.

Memory distortions are more common for peripheral/minor details than central details.

Heath and Erickson (1998)

In real-life criminal investigations, eyewitness memories can be quite robust against misleading questions.

Yuille and Cutshall (1986) studied people 5 months after a shooting they witnessed.

However, there were only 13 subjects and the extent of misinformation was modest.

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+Individual Differences

Young children and elderly adults (age 60-80) are more susceptible to misleading information. Older adults had 43% false memory compared to 4% for younger adults.

Elderly adults tend to be very confident in their false memories compared to younger adults.

Older adults are more likely to choose someone from a lineup, even when the culprit is absent.

Own Age Bias (Wright & Stroud, 2002): Accuracy of identifying someone is increased when the culprit is about as old

as the witness – older adults are more accurate for older culprits.

Perhaps people focus on features of other people like themselves.

Steps to reduce age biases: Make sure older adults and children aren’t exposed to misleading information.

Ask the elderly detailed questions to help them weed out source misattributions.

Age

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+Eyewitness Confidence

Jurors tend to be influenced by the witness’s apparent confidence.

But confidence is NOT always a good predictor of accuracy

Sporer et al. (1995) found that the correlation between confidence and accurate identification is:

Nonexistent for people who don’t make a positive identification.

Moderate (+.4) for people who do make a positive identification.

Confidence does, however, predict general knowledge accuracy.

Perfect and Hollins (1996) suggest that the difference is due to:

Having no reference point for the accuracy of eyewitness events.

Having a good idea of whether their general knowledge is more/less accurate than others’.

Witnesses are often coached to be more confident than they are.

They also receive confirming feedback from police investigators.

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+Eyewitness Confidence

Bradfield, Wells, and Olson (2002) Design: Participants were asked to identify a man they saw in a video

from a six-person lineup Confirming feedback condition: Regardless of whether they had picked the right person,

witnesses were given confirmatory feedback: “Good, you identified the actual subject”

Neutral condition: No feedback

Results: Confirming feedback increased eyewitnesses’ confidence

more when they were incorrect than when they were correct. The correlation between confidence and accuracy was

significantly worse in the confirming feedback condition.

Confirmatory Feedback

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+Influence of Anxiety and Violence

Effects of anxiety are hard to assess in the laboratory because

it’s unethical to expose participants to extremely stressful

conditions.

Typical laboratory experiments involve:

Presenting a film or a staged incident, in which a crucial event

occurs, which is either violent/nonviolent, not actual threat.

Common findings:

Memory for the central aspects of an incident are enhanced by

the presence of violence.

This is called the weapon-focus effect

Memory for the peripheral aspects of an incident are reduced by

the presence of violence.

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+Robbery Victims Frequently do not

Remember Appearance Details

Convenience stores with

frequent robberies train

their staff to notice

appearance details and

use aids such as height

strips to make this

easier.

+Influence of Anxiety and Violence

The presence of a weapon causes eyewitnesses to fail to recall other details.

Witnesses are less likely to accurately identify a target when a weapon is involved (Loftus, 1979)

Probably due to attention being naturally drawn to the weapon at the expense of other aspects of the situation

Participants spend more time looking at weapons than a nonweapon substitute (Loftus, Loftus, & Messo, 1987)

In real-life crimes the presence of a weapon:

Did not affect the rate of identifying a suspect (Valentine et al., 2003)

But this doesn’t speak to accuracy – we don’t know who was guilty.

Did have an effect according to police reports (Tollestrup et al., 1994).

Weapon-Focus Effect

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+Weapon-Focus Effect

Pickel (1999)

Proposed two possible

reasons why a weapon draws

more attention:

It poses a threat

It is unexpected

Fully crossed threat and

expectedness in four videos

he showed to participants.

Tested memory for the

person holding the gun

Found that:

Expected settings

improved the ability to ID

Threat did not influence ID

Unexpected Expected

Low

Threat

Gun pointed

at ground in a

baseball field

Gun pointed at

ground in a

shooting range

High

Threat

Gun pointed

at woman in a

baseball field

Gun pointed at

woman in a

shooting range

From Pickell (1999). Reproduced with kind permission

from Springer Science+Business Media.

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+Influence of Anxiety and Stress

Deffenbacher et al.’s (2004) meta-analyses revealed

that heightened anxiety and stress:

Negatively impact eyewitness identification accuracy – 54%

for low anxiety vs 42% for high anxiety conditions.

Reduce the ability of eyewitnesses to remember:

Culprit details –.

Crime scene details

Actions of central characters

64% high anxiety vs 52% low anxiety

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+Remembering Faces Prosopagnosia

“Face blindness”

A profound inability to recognize faces

The ability to make fine discriminations among objects is unimpaired

Commonly results from damage to the fusiform face area of the brain

This area responds more to faces than objects in normal people

Normal people’s face recognition is poorer than we’d think:

Bruce et al. (1999) asked participants to match the faces:

Results:

Only 65% accurate when the correct face

was present

35% of participants still picked a face even

when the correct face wasn’t present

Video, in conjunction with the photograph,

did not improve recognition

Copyright © American Psychological Association.

Reprinted with permission.

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+Factors Influencing Face Memory

Task:

Two groups were asked to categorize faces based on either:

Physical features (e.g. chin, nose, eyes, type of hair)

Psychological features (e.g. honesty, intelligence, liveliness)

Results:

Participants were better at recognizing faces they earlier categorized on

psychological dimensions rather than by physical features.

Adding a disguise (or removing one from the categorized face) reduced

recognition performance.

Faces seen in three quarter view are more recognizable than faces seen

in profile (side view).

Patterson and Baddeley (1977)

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+Effects of Disguises

With a wig and beard, you halve your chances of being recognized as the guilty party. Faces seen in three-quarters view are much more recognizable than faces seen in profile. From Patterson and Baddeley (1977). Copyright © American Psychological Association. Reproduced with permission.

+Holistic Face Processing

Holistic/Global Processing:

Processing the overall

structure of a face/object,

paying little attention to the

details.

Farah (1994) suggested that:

We process faces holistically.

We process objects in a more

detailed fashion.

Explains why Patterson

and Baddeley (1977) found

a benefit for psychological

categorization.

Inverted Faces

It is harder to recognize

the overall structure of a

face when it is inverted,

compared to an inverted

object.

Any difficulty recognizing

inverted objects quickly

disappears with practice.

Not true for inverted

faces.

This accounts for the

Thatcher Illusion

(Thompson, 1980)

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+Holistic Face Processing

The Thatcher Illusion

The Thatcher illusion. From Thompson, P. (1980). Margaret Thatcher: A new illusion. Perception, 9, 483–484.

Copyright © Pion Limited. Reproduced with permission..

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+Holistic Face Processing

The Thatcher Illusion

The Thatcher illusion. From Thompson, P. (1980). Margaret Thatcher: A new illusion. Perception, 9, 483–484.

Copyright © Pion Limited. Reproduced with permission..

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+Unconscious Transference

Unconscious Transference:

The tendency to misidentify a familiar (but innocent) face as

belonging to a culprit

Ross et al. (1994)

Eyewitnesses were three times more likely to select an innocent

bystander from a lineup than a stranger.

The effect was eliminated by informing them before the lineup that

the bystander was not the culprit.

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+Verbal Overshadowing

Verbal Overshadowing Effect for Faces:

Describing a previously seen face impairs recognition of that face

Schooler and Engstler-Schooler (1990).

Clare and Lewandowsky (2004)

Providing a verbal report of the culprit makes eyewitnesses more

reluctant to identify anyone in a subsequent lineup.

When forced to pick someone, the effect disappears.

Brief verbal descriptions are more likely to produce the effect than

detailed verbal descriptions.

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+Cross-Race Effect

We are more experienced distinguishing among same-race faces

Evidence:

People with more cross-race experience show smaller cross-race effects

Caveat:

The effect of expertise is small and fragile (Hugenberg et al., 2007)

Cross-race effect is eliminated by asking white participants to closely attend to facial features distinguishing black faces from each other.

Expertise Hypothesis Social-Cognitive Hypothesis

People are more accurate in recognizing same- than cross-race faces

Thorough processing of faces only occurs for individuals with whom we identify (i.e. our ingroup).

Evidence:

Shriver et al.’s (2008) white, educated participants regarded:

White faces in wealthy contexts as ingroupmembers

Both white and black faces in impoverished contexts as outgroups

Black faces in wealthy contexts as outgroupmembers

Only ingroup faces were well recognized

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+Police Lineups

Police Lineups:

A suspect is present along with

nonsuspects with broadly

similar characteristics

It is essential that the

suspect is not obviously

different from the other

members.

Valentine, Pickering, and

Darling’s (2003) analysis of 314

real lineups:

40% identified the suspect

20% identified a nonsuspect

40% failed to ID anyone

Methods to improve lineups:

Warn eyewitnesses that the culprit may not be present in the lineup:

Steblay (1997)

Reduces mistaken IDs by 42%

Only reduces positive IDs by 2%

Present members of the lineup sequentially instead of simultaneously

Results in a more stringent criterion:

Reduces mistaken IDs by about 50%

Also significantly reduces positive IDs

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+Police Interviews

Inadequate Technique More Effective

Technique

Result

Close-ended questioning

•“What color was the car?”

Open-ended questioning

•“What can you tell me about

the car?”

Generates more complete

responses without leading

the witness

Interrupting the witness Allowing the witness time to

finish responding

Doesn’t disrupt

concentration/retrieval cues

Asking questions in a

predetermined order

Ask relevant follow-up

questions

Takes account of previous

answers

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+Improving Police Interviews

Retrieval Rule Empirical Basis Goal

Mental reinstatement

of contextEncoding Specificity

Principle

Improve the match

between encoding and

retrieval contextsEncouraging complete

reporting (even small

details)

Attempting to describe

the events in several

different orders Memory traces are

complex and contain

various features

Prompting access to

multiple, different cues

improves recallReporting the incident

from different

viewpoints

The Cognitive Interview (Geiselman et al., 1985)

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+Improving Police Interviews

In addition to the four rules, investigators should:

Minimize distractions

Induce the subject to speak slowly

Allow for a pause between responses and new questions

Use appropriate language for the witness

Follow up responses with an interpretive comment

Try to reduce eyewitness anxiety

Avoid judgmental and personal comments

Review the eyewitness’s description of events/people under

investigation

Enhanced Cognitive Interview (Fisher et al., 1987)

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+Comparing Interview Methods

The Cognitive Interview:

Generally produces the most accurate information

Caveats:

Yields slightly more false information than most people given the standard interview (Kohnken et al., 1999)

It is most effective when conducted immediately after the crime

It is more valuable for recalling peripheral than central details (Groeger, 1997)

It is not yet clear how the individual guidelines of the interview contribute to its effects

Hypnosis is controversial, as it increases:

People’s suggestibility

The amount of false information reported

Based on data in Geiselman et al. (1985).

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+Laboratory vs. Real-Life Settings

In contrast to real-life scenarios, laboratory conditions:

Tend to ask for information from individuals not directly involved in

the crime (i.e. not the victims themselves)

Are less stressful and anxiety-provoking

Provide the eyewitness with only a single, passive perspective

They cannot move around or interact with other participants in the

event

Typically grant witnesses far less time to view the event/people

Carry only minimal consequences for inaccurate information or false

identifications

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+The Role of Experts

Leippe’s (1995) review of mock-juror/trial studies

The use of experts in eyewitness testimony during a trial:

Makes jurors more skeptical of eyewitness testimony

Reduces guilty verdicts

Leippe et al. (2004)

The presence of expert testimony produced a sizeable reduction in

guilty verdicts, regardless of the overall strength of the case

Thus, it may make jurors unfairly weight potential pitfalls over

otherwise strong evidence.

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+The Case Against Expert Testimony

Conclusions experts might offer are likely debatable given highly inconsistent evidence.

e.g. about equal numbers of studies report that high arousal increases (or decreases) eyewitness accuracy.

Most research on eyewitness memory emphasizes situational factors, largely ignoring individual differences.

Factors that influence eyewitness memory are interactive; however, they are usually studied in isolation.

No empirical data convincingly demonstrates that the testimony of defense experts can actually improve the accuracy of jury decisions.

In fact, it is often prejudicial.

Ebbesen and Konecni (1997)

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+The Value of Laboratory Research

Lindsay and Harvie (1988)

Slideshows, videos, and live staged events all produce roughly equivalent accuracy rates

Ihlebaek et al. (2003)

Memory for both live staged and videotaped robberies is:

Exaggerated in terms of the duration of the event

Largely similar in terms of what was remembered/not remembered

Yet, watching a videotaped version of events yields more information

e.g. better estimates of robber’s age, height, weight, and weapon used

Conclusions:

Witnesses to real-life events are more inaccurate than those who observe the events under laboratory conditions

Memory distortions/inaccuracies in the laboratory provide an underestimate of real-life memory deficiencies

Thus, laboratory research can still be relevant

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+Do Jurors Need Expert Advice?

The same factors that are important in the laboratory influence

real-life police cases (Tollestrup et al., 1994)

e.g. exposure duration, weapon focus, and retention interval

Mock jurors cannot discriminate between accurate and

inaccurate witnesses (Leippe, 1995)

Inaccurate witnesses are mistakenly judged to be accurate by 40–

80% of mock jurors

Mock jurors do not adequately moderate their verdicts based

on factors influencing eyewitness accuracy, like lighting

conditions (Lindsay et al., 1986)

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+The Case For Expert Testimony Cutler, Penrod, and Dexter (1989)

Design:

Mock jurors viewed realistic videotaped trial of an armed robbery

A witness made an ID of a subject under good or bad conditions

Expert advice was either offered or not

Results:

Expert testimony led jurors to better weigh the quality of the ID conditions

Conclusion:

Jurors not exposed to eyewitness testimony were largely insensitive to the quality of witnessing and ID conditions

Good Conditions Bad Conditions

Robber not disguised Robber disguised

Weapon was hidden from view Weapon was exposed

ID took place 2 days after robbery ID took place 14 days after robbery

Lineup instructions not suggestive Suggestive lineup instructions

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+The Case For Expert Testimony

Jurors who hear expert testimony make more accurate

decisions than those who have not (Cutler & Penrod, 1995).

Experts only discuss findings from eyewitness research that

are generally agreed to be well established.

They are forbidden to discuss the research in relation to the

specifics of the case, leaving the jurors to decide what is relevant.

While the admission of expert advice isn’t perfect, it does

generally level the playing field and assist in making jurors

reasonably more skeptical of eyewitness testimony.

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