PSYC1001 Lecture Notes - Lecture 4: Eyewitness Testimony, Eyewitness Memory, Recognition Memory
26 May 2018
School
Department
Course
Professor
Crime Investigation: Witnesses I
1. Background
a. Eyewitness testimony: commonly used as evidence in court
i. US: 77000 arrested purely based on eyewitness testimonies
ii. Most persuasive, compelling
iii. Important to establish whether juror’s faith is warranted
iv.Many psychologists argue eyewitness memory is not as reliable as perceived to
be
b. Assessed in two ways
i. Recall memory: reporting details of event/person
ii. Recognition memory: reporting whether what is currently being viewed/heard is
same as the previously witnessed person/event of interest
1. Compare own memory
2. Estimator variables & system variables
a. Two types affecting memory
i. Estimator variables: present at the time of the crime and cannot be changed
ii. System variables: manipulated after the fact & impact the accuracy of witnesses
b. Estimator variables
i. Features of an event can influence a person’s perception
1. Exposure time, lighting, distance, physical disguise, distraction, alcohol/drugs
(state dependency)
2. People don’t know when a crime is going to happen; they inevitably miss
crucial details
3. People don’t always see what is there
ii. Expectations affect perception
1. People construct memories partly on what we perceived at the time, partly on
our expectations, beliefs, current knowledge
iii. Own race bias
1. Tendency to have difficulty identifying people of another race
2. More likely to identify same race
3. Likely due to a lack of interracial contact
iv.What effect does stress have on memory?
1. Yerkes-Dodson law: memory best at optimum level of arousal
2. Easterbrook hypothesis (more helpful): highly aroused witnesses have better
memory for central details (flashbulb memory) than peripheral details
3. Weapons focus effect: presence of a weapon draws attention and impairs a
witness’ ability to identify a culprit
a. Independent variable: gun or checkbook
b. Dependent variables: eye movement and accuracy of identification
c. Less likely to identify person in a lineup b/c people spend more time
looking at the weapon
d. Those who pay attention to details: less likely to pay attention to culprit’s
face
c. System variables
i. Questioning techniques used by police can affect eyewitness accuracy
3. Misinformation effect
a. Misinformation effect: exposure to incorrect information about an event after it has
occurred
i. McMartin Preschool
b. Fit answers to questions asked
4. False/repressed memory debate
a. False memories
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