Eyewitness Memory
Bob Campbell
Lourdes University
Eyewitness Testimony
Loftus & Palmer (1974)
Contact speed was 31.8 mph
Smashed speed was 40.8 mph
12% (contact) incorrectly recalled broken
glass
32% (smashed) incorrectly recalled
broken glass
The Problem of Duality of
Error in Law
Convicting the innocent
Acquitting the guilty
Beyond a reasonable doubt protects the
individual at possible cost to society
Preponderance of evidence protects the
society at possible cost to the individual
Hammond (1996)
Estimator and System
Variables
Some factors that influence the accuracy
of eyewitness testimony are beyond the
control of the justice system
Other factors that influence the accuracy
of eyewitness testimony can be controlled
by the justice system
Wells (1978)
At the Scene of an Accident
or Crime
The behavior of the officer at the scene
of an accident or crime is a system
variable which may alter the memory of
the witness
Expectations
Hall et al. (1978)
Expectations of the police officer at the
scene may influence the witness
The officer at the scene must be careful
not to impart information to the witness
either verbally or nonverbally
Type of Question Asked
Free Narrative such as “What did you
see?”
Controlled Narrative such as “What was
the assailant wearing?”
Interrogatory Reports such as “Where did
the incident happen: in a lot, in the street,
or on the sidewalk?”
Accuracy versus
Completeness
Accuracy: Free, Controlled, Interrogatory
Completeness: Interrogatory, Controlled,
Free
Officer on the scene must be aware of
the need to balance the quest for
accuracy with the need for completeness
The Effects of DNA Evidence
A recent study identified 62 individuals
convicted of crimes they did not commit
52 cases involved mistaken identification
on the part of 77 highly confident
eyewitnesses
Scheck, Neufeld, & Dwyer (2000)
As of 2010, 254 individuals exonerated as
a result of “project innocence”
The Guide
In 1999 the US Justice Department
created a guide for law enforcement that
details the handling of an eyewitness to
an accident or crime
Panel consisted of 34 experts from law
enforcement, the legal profession, and
academia
Recommendations
Encourage rapport with the eyewitness
and encourage them to talk freely
Conduct the interview at a slow pace and
ask primarily open ended questions
Communicate your investigative needs to
the witness
System Variables
Avoid surrounding a potentially innocent
suspect with dissimilar fillers
The eyewitness should be instructed prior
to viewing the lineups that the suspect
may or may not be in the lineup
System Variables Continued
Present sequential rather than
simultaneous lineups
Avoid giving the eyewitness feedback about
the accuracy of the identification after a
selection has been made
This must be done before assessing the
confidence of the eyewitness
Eyewitness Research
Campbell (2003)
Control 45% accuracy 66% confidence
Exp 75% accuracy 74% confidence
Extra
Extra
0
