Eyewitness identification

In forenstic context

Memory errors lead to false identifications.

Innocence project

330 DNA exonerations of innocents wrongfully imprisoned and 75 % have involved mistaken identifications.

System Variables

Factors affecting identifications influenced by criminal justice system (e.g., lineups, questioning)

Estimator Variables

Factors effecting identifications not influenced by criminal justice system (e.g., exposure time, stress, lighting).

Reasons why memory errors are common

1. Confabulation

2. Source Misattribution

3. Criterion Shifts

4. Breakdowns in reality monitoring

Confabulation

Filling in gaps with with information about what “Likely” happened.

Source Misattribution

We recall the information but forget where we learned it.

Criterion shifts

People adjust how certain they feel they must be to report a memory based on pressures to recall more.

Breakdowns in reality monitoring

Difficulty distinguishing between real events and those we imagined.

Memory is a 3-stage process:

1. Encoding

2. Storage

3. Retrieval

Encoding errors and memory

1. People must fully attend to the information in order for it to be properly encoded.

2. Short time durations and distraction can dramatically interfere with the encoding stage.

Weapon focus

• We remember less details about the perpetrator when a weapon is present.

• Stress reduces our cognitive capacity, so we process information less fully.

Accuracy- confidence relation

Jurors have difficulty distinguishing between accurate and inaccurate witnesses- they rely on confidence.

Confident Witnesses

1. Only a small to moderate relation between confidence and accuracy.

Coached to appear confident.

Rarely gets feedback about memory errors.

Confidence is an individual difference characteristic.

Schemas

• Mental representations which assist in storage and retrieval.

• It is a network of knowledge, beliefs and expectations about particular aspects of the world.

Schemas are examples of what?

Top down processing

Brewer & Treyens (1981)

Demonstrated that individuals recall schema-consistent information,

regardless of whether they were previously exposed to the information.

confabulation*

Some questions will call up schemas and we fill in the gaps with information we cannot recall.

The misinformation effect

Is the tendency for misinformed participants to be less accurate than non-misinformed.

Functional size

refers to the number of possible suspects

Nominal size

refers to the number of members in the lineup

Witnesses use relative judgment strategies… Meaning?

They choose the member of the lineup who looks most like the

person they recall.

Alternatives to Simultaneous Lineups

1. Showups

2. Sequential Lineups

Showups

Each suspect is presented one at a time. One person

Sequential Lineups

Each lineup member is brought out individually. Eyewitness does

not know how many lineup members he will see.

Target Absent Lineups

Contain no suspects. Identifies unreliable witnesses.

Mock witness control

View lineup based only on physical description given by witness. Pattern of choices suggest lineup is biased.

Double blind lineups

Both the witness and the police officer handling the lineup do not know who the suspect is.

• Will reduce likelihood of Post-Identification Feedback (PIF)

Other Race Effect

We make more identification errors for other races.

Facial Composite Production by Eyewitnesses

Composites can bias the eyewitness away from the original face and toward a face that resembles the composite.

Study of composite quality include:

1. Matching tasks

2. Naming Tasks

3. Similarity-rating tasks

Matching tasks

Subjects choose among lineup of photos.

Naming Tasks

What famous person is this?

Similarity-rating tasks

How similar is the composite to the actual face?