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
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Extra
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