Eyewitness Testimony: Memory, Lineups, and Policy in Forensic Psychology

Chapter 5: Eyewitness Testimony

Learning Objectives

• Understand the components of eyewitness memory.

• Describe two categories of independent variables and three dependent variables found in eyewitness research.

• Describe recall memory in an eyewitness context. Describe lineup procedures and how they may be biased.

• Summarize the debate surrounding expert testimony on eyewitness issues.

• Outline the recommendations for collecting eyewitness identification evidence.

Understanding Eyewitness Memory

Stages of Memory

Eyewitness memory involves three main stages: encoding, storage, and retrieval. Each stage can be influenced by various factors, affecting the accuracy and reliability of eyewitness testimony.

• Encoding: The process of perceiving and registering information about an event.

• Storage: Maintaining the encoded information over time.

• Retrieval: Accessing the stored information when needed, such as during police interviews or court testimony.

Memory can be influenced at all stages by situational and personal factors, such as stress, attention, and the presence of a weapon.

Eyewitness Memory Retrieval

Recall vs. Recognition Memory

Recall Memory	Recognition Memory
Reporting details of a previously witnessed event or person.	Determining whether a previously seen item or person is the same as what is currently being viewed.
Example: Describing the perpetrator's appearance to police.	Example: Identifying a suspect in a police lineup.

Variables in Eyewitness Research

Independent Variables

Independent variables are factors that can be manipulated or examined in research to assess their effect on eyewitness memory. They are divided into:

• Estimator Variables: Factors present at the time of the crime and cannot be controlled by the justice system (e.g., lighting, stress, presence of a weapon).

• System Variables: Factors under the control of the justice system (e.g., lineup procedures, interview techniques).

Dependent Variables

The main dependent variables in eyewitness studies are:

• Recall of the crime

• Recall of the perpetrator

• Recognition of the perpetrator

Recall can be measured through:

• Open-ended recall (free narrative): Witnesses describe everything they remember without prompts.

• Direct question recall: Witnesses answer specific questions about the crime or perpetrator.

Lineup Procedures and Bias

Types of Lineups

• Simultaneous Lineup: All lineup members are presented at once.

• Sequential Lineup: Lineup members are presented one at a time; the witness must decide on each before seeing the next.

• Show-up: Only one person (the suspect) is shown to the witness.

• Walk-by: The witness observes people in a natural setting to identify the perpetrator.

Judgment Types

• Relative Judgment: Comparing lineup members to each other to pick the most similar to the perpetrator.

• Absolute Judgment: Deciding if a lineup member matches the memory of the perpetrator without comparison to others.

Lineup Bias

• Biased Lineup: Suggests to the witness whom to identify.

• Fair Lineup: The suspect does not stand out from other lineup members.

Other Influences

• Cross-race Effect: Witnesses are better at recognizing faces of their own race.

• Weapon Focus: Attention is drawn to a weapon, reducing recall of other details.

The Misinformation Effect

Definition

The misinformation effect occurs when a witness incorporates incorrect information presented after an event into their memory of the event.

• Misinformation acceptance hypothesis: Witnesses accept incorrect information as true.

• Source misattribution hypothesis: Witnesses confuse the source of information (original vs. misinformation).

• Memory impairment hypothesis: The original memory is replaced by the incorrect information.

Interviewing Eyewitnesses

Procedures to Improve Accuracy

• Hypnosis: Sometimes used to recover more information, but its reliability is debated.

• The cognitive interview: Uses memory retrieval techniques to increase recall, such as reinstating the context, recalling events in different orders, and changing perspectives.

• Enhanced cognitive interview: Adds techniques like building rapport, minimizing interruptions, and asking open-ended questions.

Recognition Memory and Lineup Types

Testing Recognition Memory

• Live lineups or photo arrays

• Video surveillance records

• Voice identification

Key Terms

• Suspect: The person police believe may have committed the crime.

• Perpetrator: The actual person who committed the crime.

• Foils/Distractors: Innocent lineup members.

• Target-present lineup: The perpetrator is in the lineup.

• Target-absent lineup: The perpetrator is not in the lineup.

Public Policy Issues and Guidelines

Recommendations for Collecting Eyewitness Identification Evidence

1. The lineup administrator should not know which member is the suspect (double-blind procedure).

2. Witnesses should be told that the perpetrator may not be present in the lineup.

3. The suspect should not stand out in the lineup.

4. A clear statement should be taken from the witness at the time of identification, documenting their confidence level.

Summary Table: Types of Variables in Eyewitness Research

Variable Type	Definition	Examples
Estimator Variables	Factors present at the time of the crime, not controlled by the justice system	Lighting, stress, weapon presence
System Variables	Factors controlled by the justice system	Lineup instructions, interview methods

Additional info: These notes expand on the original content by providing definitions, examples, and structured explanations to ensure clarity and completeness for exam preparation.