Cognitive Biases in Criminal Case Evaluation: A Review of

Vol.:(0123456789)1 3

https://doi.org/10.1007/s11896-020-09425-8

REVIEW ARTICLE

Cognitive Biases in Criminal Case Evaluation: A Review of the Research

Vanessa Meterko1 · Glinda Cooper1

Accepted: 8 December 2020 © The Author(s) 2021

AbstractPsychological heuristics are an adaptive part of human cognition, helping us operate efficiently in a world full of complex stimuli. However, these mental shortcuts also have the potential to undermine the search for truth in a criminal investigation. We reviewed 30 social science research papers on cognitive biases in criminal case evaluations (i.e., integrating and drawing conclusions based on the totality of the evidence in a criminal case), 18 of which were based on police participants or an examination of police documents. Only two of these police participant studies were done in the USA, with the remainder conducted in various European countries. The studies provide supporting evidence that lay people and law enforcement professionals alike are vulnerable to confirmation bias, and there are other environmental, individual, and case-specific factors that may exacerbate this risk. Six studies described or evaluated the efficacy of intervention strategies, with varying evidence of success. Further research, particularly in the USA, is needed to evaluate different approaches to protect criminal investigations from cognitive biases.

Keywords Cognitive bias · Confirmation bias · Police · Investigation

Introduction

Decades of research in cognitive and social psychology have taught us that there are limitations to human attention and decision-making abilities (see, for example, Gilovich et al. 2002). We cannot process all the stimuli that surround us on a daily basis, so instead we have adapted for efficiency by attuning to patterns and developing mental shortcuts or rules of thumb to help us effectively navigate our complex world. While this tendency to rely on heuristics and biases can serve us well by allowing us to make quick decisions with little cognitive effort, it also has the potential to inad-vertently undermine accuracy and thus the fair administra-tion of justice.

Cognitive bias is an umbrella term that refers to a variety of inadvertent but predictable mental tendencies which can impact perception, memory, reasoning, and behavior. Cogni-tive biases include phenomena like confirmation bias (e.g., Nickerson 1998), anchoring (e.g., Tversky & Kahneman 1974), hindsight bias (e.g., Fischhoff 1975), the availability

heuristic (e.g., Tversky & Kahneman 1973), unconscious or implicit racial (or other identifying characteristics) bias (e.g., Greenwald et al. 1998; Staats et al. 2017), and others. In this context, the word “bias” does not imply an ethical issue (e.g., Dror 2020) but simply suggests a probable response pattern. Indeed, social scientists have demonstrated and discussed how even those who actively endorse egalitarian values harbor unconscious biases (e.g., Pearson et al. 2009; Richardson 2017) and how expertise, rather than insulating us from biases, can actually create them through learned selective attention or reliance on expectations based on past experiences (e.g., Dror 2020). Consequently, we recognize the potential for these human factors to negatively influence our criminal justice process.

In an effort to explore the role of cognitive biases in crim-inal investigations and prosecutions, we conducted a litera-ture review to determine the scope of available research and strength of the findings. The questions guiding this exercise were as follows: (1) what topics have been researched so far and where are the gaps?; (2) what are the methodological strengths and limitations of this research?; and (3) what are the results, what do we know so far, and where should we go from here? * Vanessa Meterko

[email protected]

1 Science & Research Department, Innocence Project, New York, NY, USA

/ Published online: 23 June 2021

Journal of Police and Criminal Psychology (2022) 37:101–122

http://orcid.org/0000-0002-1207-8812

http://crossmark.crossref.org/dialog/?doi=10.1007/s11896-020-09425-8&domain=pdf

1 3

Methods

We searched PsycINFO for scholarly writing focused on cognitive biases in criminal investigations and prosecutions in December 2016 and again in January 2020.1 We reviewed all results by title and then reviewed the subset of possibly-relevant titles by abstract, erring on the side of over-inclusivity. We repeated this process using the Social Sciences Full Text, PubMed, and Criminal Justice Abstracts with Full Text databases to identify additional papers. Finally, we manually reviewed the reference lists in the identified papers for any unique sources we may have missed in prior searches.

We sorted the articles into categories by the actor or action in the criminal investigation and prosecution process that they addressed, including physical evidence collection, witness evaluation, suspect evaluation, forensic analysis and testimony, police case evaluation (i.e., inte-grating and drawing conclusions based on the totality of the evidence), prosecutors, defense attorneys, judges, juries, and sentencing. Within each of these categories, we further sorted the articles into one of three types of sources: “primary data studies” describing experimental or observational studies that involved data collection or analysis, “intervention studies” that were solution- oriented and involved implementing some type of intervention or training to prevent or mitigate a phenomenon, and “secondary sources” (e.g., commentaries, letters, reviews, theoretical pieces, general book chapters) that discussed cognitive biases but did not present primary data.

To narrow the scope of this review, we did not include articles that focus solely on implicit racial bias or struc- tural racial bias in the criminal legal system. The foun- dational and persistent problem of racial (particularly anti-Black) bias throughout our legal system—from polic-ing to sentencing (e.g., Voigt et al. 2017; NYCLU 2011; Blair et al. 2004; Eberhardt et al. 2006)—has been clearly demonstrated in laboratory experiments and analyses of real-world data and is well-documented in an ever-growing body of academic publications and policy reports (e.g., Correll et al. 2002; Chanin et al. 2018; Owens et al. 2017; Staats et al. 2017).

Results

Scope of Available Research and Methodology

Cognitive biases in forensic science have received the most attention from researchers to date (for a review of these forensic science studies, see Cooper & Meterko 2019). The second most substantial amount of scholarship focused on case evaluation (i.e., integrating and drawing conclusions based on the totality of the evidence in a case). Ultimately, we found 43 scholarly sources that addressed various issues related to the evaluation of the totality of evidence in crimi-nal cases: 25 primary data (non-intervention) studies, five intervention studies, and one additional paper that presented both primary data and interventions, and 12 secondary sources. For the remainder of this article, we focus solely on the primary data and intervention studies. One of the primary data studies (Fahsing & Ask 2013) described the development of materials that were used in two subsequent studies included in this review (Fahsing & Ask 2016; 2017), and thus, this materials-development paper is not reviewed further here. Table 1 presents an overview of the research participants and focus of the other 30 primary data and inter-vention studies included in our review.

One challenge in synthesizing this collection of research is the fact that these studies address different but adja-cent concepts using a variety of measures and—in some instances—report mixed results. The heterogeneity of this research reveals the complex nature of human factors in criminal case evaluations.

Eighteen of the 30 papers (13 primary data and three intervention) included participants who were criminal jus-tice professionals (e.g., police, judges) or analyzed actual police documents. An appendix provides a detailed sum-mary of the methods and results of the 18 criminal justice participant (or document) studies. Fifteen papers were based on or presented additional separate analyses with student or lay participants. Recruiting professionals to participate in research is commendable as it is notoriously challenging but allows us to identify any differences between those with training and experience versus the general public, and to be more confident that conclusions will generalize to real-world behavior. Of course, representativeness (or not) must still be considered when making generalizations about police investigations.

Reported sample sizes ranged from a dozen to several hundred participants and must be taken into account when interpreting individual study results. Comparison or control groups and manipulation checks are also essential to accu-rately interpreting results; some studies incorporated these components in their designs while others did not.

1 We used the following search terms and Boolean Operators: (crimi-nal OR justice OR police OR investigat* OR forensic* OR jury OR juries OR judge* OR conviction* OR prosecut* OR defense OR defender* OR attorn*) in any field (e.g., text, title) AND (“cogni-tive bias” OR “cognitive dissonance” OR “tunnel vision” OR “con-firmation bias” OR “interpretive bias” OR “belief perseverance” OR “asymmetrical skepticism”) in any field (e.g., text, title).

102 Journal of Police and Criminal Psychology (2022) 37:101–122

1 3

Tabl

e 1

Ove

rvie

w o

f 30

pape

rs o

n co

gniti

ve b

iase

s in

crim

inal

cas

e ev

alua

tion

Rese

arch

focu

s

Aut

hors

(Yea

r)Lo

catio

nPa

rtici

pant

saSa

mpl

e si

zeH

uman

nat

ure

Envi

ronm

ent a

nd

cultu

reIn

divi

dual

ch

arac

teris

tics

Cas

e-

spec

ific

Inte

rven

tion

Ask

and

Gra

nhag

(2

005)

Swed

enSt

udy

1: P

olic

e;St

udy

2: S

tude

nts o

r co

mm

unity

Stud

y 1:

50;

Stud

y 2:

68

Dis

posi

tiona

l des

ire

for c

losu

re

Ask

and

Gra

nhag

(2

007a

)Sw

eden

Polic

e61

Emot

iona

l sta

te

Ask

and

Gra

nhag

(2

007b

)Sw

eden

Polic

e49

Asy

mm

etric

al

skep

ticis

mTi

me

pres

sure

Ask

et a

l. (2

008)

Swed

enPo

lice

117

Asy

mm

etric

al

skep

ticis

mTy

pe o

f ev

iden

ceA

sk e

t al.

(201

1a)

Swed

enPo

lice

104

Org

aniz

atio

nal

norm

s of

effici

ency

ver

-su

s tho

roug

h-ne

ssA

sk e

t al.

(201

1b)

Ger

man

ySt

udie

s 1 a

nd 2

: Stu

dent

s or

com

mun

itySt

udy

1: 4

7; S

tudy

2:

60

Cog

nitiv

e di

sso-

nanc

e; a

sym

- m

etric

al

skep

ticis

m

Type

of

evid

ence

Cha

rman

et a

l. (2

015)

USA

Stud

ents

or c

omm

unity

382

Con

text

effe

cts;

re

cenc

y eff

ects

Cha

rman

et a

l. (2

017)

USA

Polic

e an

d stu

dent

s or

com

mun

ity89

(pol

ice)

and

227

(s

tude

nts)

Con

firm

atio

n bi

as

Ditr

ich

(201

5)A

ustri

aPo

lice

Not

repo

rted

Vario

us c

ogni

tive

falla

cies

Dan

do a

nd

Orm

erod

(201

7)U

nite

d

Kin

gdom

Polic

e60

Leve

l of e

xper

ienc

eTy

pe o

f cr

ime

Eerla

nd e

t al.

(201

2)N

ethe

rland

sSt

uden

ts o

r com

mun

ity63

Feat

ure

posi

tive

effec

tEe

rland

and

Ras

sin

(201

2)N

ethe

rland

sSt

uden

ts o

r com

mun

ity18

8C

onfir

mat

ion

bias

; Fe

atur

e po

sitiv

e eff

ect

Fahs

ing

and

Ask

(2

016)

bN

orw

ay a

nd

Engl

and

Polic

e12

4Ty

pe o

f tra

inin

gLe

vel o

f exp

erie

nce

Tipp

ing

poin

tFa

hsin

g an

d A

sk

(201

7)b

Nor

way

Polic

e16

6Re

ason

ing

abili

ties

Tipp

ing

poin

tG

reen

span

and

Su

rich

(201

6)U

SASt

udie

s 1 a

nd 2

: Stu

dent

s or

com

mun

itySt

udy

1: 1

19; S

tudy

2:

127

Coh

eren

ce-b

ased

re

ason

ing

103Journal of Police and Criminal Psychology (2022) 37:101–122

1 3

Tabl

e 1

(con

tinue

d)

Rese

arch

focu

s

Aut

hors

(Yea

r)Lo

catio

nPa

rtici

pant

saSa

mpl

e si

zeH

uman

nat

ure

Envi

ronm

ent a

nd

cultu

reIn

divi

dual

ch

arac

teris

tics

Cas

e-

spec

ific

Inte

rven

tion

Gro

enen

daal

and

H

elsl

oot (

2015

)N

ethe

rland

sPo

lice

60C

rimin

al In

vesti

gatio

n Re

info

rcem

ent P

ro-

gram

me

Haa

s et a

l. (2

015)

Switz

erla

ndSt

uden

ts o

r com

mun

ity12

7Tr

aini

ng a

nd c

heck

list

tool

Jone

s et a

l. (2

008)

Uni

ted

K

ingd

omPo

lice

12Re

view

tool

Ker

stho

lt an

d Ei

kel-

boom

(200

7)N

ethe

rland

sPo

lice

38G

roup

thin

kLe

vel o

f exp

erie

nce

Mar

kste

iner

et a

l. (2

010)

Swed

enPo

lice

107

Asy

mm

etric

al

skep

ticis

mO

’Brie

n (2

009)

/O’B

rien

(200

7)c

USA

Stud

ies 1

and

2: S

tude

nts

or c

omm

unity

Stud

y 1:

108

; Stu

dy

2: 1

09C

onfir

mat

ion

bias

Crim

e

seve

rity

Gen

erat

ing

alte

rnat

ive

hypo

thes

es,

chal

leng

ing

a hy

poth

-es

is, a

ccou

ntab

ility

to

proc

ess o

r out

com

e,

need

to p

ersu

ade

othe

rsPr

ice

and

Dah

l (2

014)

Can

ada

Stud

ents

or c

omm

unity

179

Rece

ncy

effec

ts

Ras

sin

(201

0)N

ethe

rland

sSt

udy

1: P

olic

ed ;St

udy

2: S

tude

nts o

r co

mm

unity

Stud

y 1:

118

; Stu

dy

2: 1

78St

udy

1: C

onfir

ma-

tion

bias

Stud

y 2:

D

ispo

sitio

nal d

esire

fo

r clo

sure

Ras

sin

(201

8a)

Net

herla

nds

Stud

y 2:

Stu

dent

s or

com

mun

itye

71Re

ason

ing

abili

ties

Ras

sin

(201

8b)

Net

herla

nds

Stud

y 1:

Stu

dent

s or

com

mun

ity;

Stud

y 2:

Pol

iced

Stud

y 1:

277

;St

udy

2: 4

5Pe

n an

d pa

per t

ool

Ras

sin

et a

l. (2

010)

Net

herla

nds

Stud

ies 1

–3: S

tude

nts o

r co

mm

unity

Stud

y 1:

79;

Stu

dy

2: 1

29; S

tudy

3:

182

Con

firm

atio

n bi

asC

rime

seve

rity

Sale

t and

Ter

pstra

(2

014)

Net

herla

nds

Polic

e26

(cas

e fil

es) a

nd

47 (i

nter

view

s)U

se o

f “co

ntra

rians

” an

d “c

ritic

al re

view

” pr

oced

ures

Sim

on e

t al.

(200

4)U

SASt

udie

s 1 a

nd 2

: Stu

dent

s or

com

mun

itySt

udy

1: 1

54; S

tudy

2:

344

Coh

eren

ce-b

ased

re

ason

ing

Wal

lace

(201

5)U

SAPo

lice

166

Con

firm

atio

n bi

asLe

vel o

f exp

erie

nce

Crim

e

seve

rity


1 3

Most studies used vignettes or case materials—both real and fictionalized—as stimuli. Some studies did not include enough information about stimulus or intervention materials to allow readers to critically interpret the results or repli-cate an intervention test. Future researchers would benefit from publishers making more detailed information avail-able. Further, while the use of case vignettes is a practi-cal way to study these complex scenarios, this approach may not completely mimic the pressures of a real criminal case, fully appreciate how the probative value of evidence can depend on context, or accurately reflect naturalistic decision-making.

Notably, only two of the criminal case evaluation studies using professional participants were conducted in the USA; all others were based in Europe (Austria, Netherlands, Nor-way, Sweden, and the UK). The differences between police training, operations, and the criminal justice systems writ large should be considered when applying lessons from these studies to the USA or elsewhere.

Finally, all of these papers were published relatively recently, within the past 15 years. This emerging body of research is clearly current, relevant, and has room to grow.

Research Findings

The primary data studies address a constellation of con-cepts that demonstrate how human factors can inadvertently undermine the seemingly objective and methodical process of a criminal investigation. To organize these concepts, we used a taxonomy originally developed to describe potential sources of bias in forensic science observations and conclu-sions as a guide (Dror 2017; Dror et al. 2017) and adapted it to this collection of case evaluation literature.2 As in Dror’s taxonomy, the broad base of this organizing pyramid is “human nature,” and as the pyramid narrows to its peak, potential sources of bias become increasingly dependent on environmental, individual, and case-specific circumstances and characteristics (Fig. 1). Some authors in this collection address more than one of these research areas within the same paper through multiple manipulations or a series of studies (Table 1).

Human Nature

The “human nature” studies include those that demonstrate universal psychological phenomena and their underlying mechanisms in the context of a criminal case evaluation. Several studies focused on confirmation bias. Confirmation

a “Pol

ice”

par

ticip

ant s

tudi

es w

ere

thos

e th

at u

sed

polic

e pe

rson

nel (

incl

udin

g po

lice

office

rs, c

rimin

al in

vesti

gato

rs, c

rime

anal

ysts

, pol

ice

train

ees

or re

crui

ts) o

r a re

view

of p

olic

e do

cum

ents

(in

clud

ing

inve

stiga

tive

case

file

s or

dec

isio

n lo

gs);

“Stu

dent

s or

com

mun

ity”

parti

cipa

nt s

tudi

es w

ere

thos

e th

at u

sed

unde

rgra

duat

e stu

dent

s, gr

adua

te s

tude

nts,

law

stu

dent

s, U

S ci

tizen

s, or

a

gene

ral p

ublic

/onl

ine

sam

ple

b Fahs

ing

and

Ask

dev

elop

ed m

ater

ials

for t

hese

stud

ies i

n 20

13 b

y co

nduc

ting

sem

i-stru

ctur

ed in

terv

iew

s to

elic

it fa

ctor

s tha

t cou

ld d

isru

pt o

ptim

al d

ecis

ion-

mak

ing

in h

omic

ide

inve

stiga

tions

; us

ed c

onte

nt a

naly

sis t

o de

velo

p ca

tego

ries o

f tip

ping

poi

nts (

nam

ing,

arr

estin

g, o

r cha

rgin

g a

susp

ect,

choi

ce o

f mai

n hy

poth

eses

or l

ines

of i

nqui

ry) a

nd re

late

d si

tuat

iona

l (av

aila

bilit

y of

info

r-m

atio

n/ev

iden

ce, e

xter

nal p

ress

ure/

com

mun

ity im

pact

, int

erna

l pre

ssur

e/or

gani

zatio

nal i

ssue

s, tim

e pr

essu

re) a

nd in

divi

dual

(det

ectiv

e ex

perie

nce,

trai

ning

and

edu

catio

n, p

erso

nal c

hara

cter

is-

tics)

fact

ors

c O’B

rien’

s 20

09 p

ublic

atio

n in

clud

es a

sub

set o

f stu

dies

from

her

200

7 di

sser

tatio

n. C

onse

quen

tly, t

he n

umbe

ring

of s

tudi

es in

thes

e tw

o pa

pers

is d

iffer

ent:

publ

ishe

d “S

tudy

1” =

diss

erta

tion

“Stu

dy 2

” (N

= 1

08) a

nd p

ublis

hed

“Stu

dy 2

” = di

sser

tatio

n “S

tudy

3”

(N =

109

). Th

e 20

07 d

isse

rtatio

n al

so re

porte

d on

a S

tudy

1 (N

= 5

0), a

Stu

dy 4

(N =

123

), an

d a

Stud

y 5

(N =

96)

, all

with

stud

ent p

artic

ipan

ts a

s wel

l. Th

e nu

mbe

rs in

this

tabl

e ar

e ta

ken

from

the

publ

ishe

d pa

per

d In a

dditi

on to

pol

ice

office

rs, t

hese

stud

ies i

nclu

ded

othe

r crim

inal

justi

ce p

rofe

ssio

nal p

artic

ipan

ts (d

istric

t atto

rney

s and

judg

es)

e Ras

sin

2018

a al

so in

clud

ed a

Stu

dy 1

, a d

escr

iptiv

e an

alys

is o

f log

ical

reas

onin

g sk

ills i

n a

sam

ple

of 2

08 st

uden

ts a

nd 4

0 cr

imin

al tr

ial j

udge

s. Th

is st

udy

did

not a

ttem

pt to

ana

lyze

reas

onin

g sk

ills i

n re

latio

n to

asp

ects

of c

ase

eval

uatio

n, a

nd so

this

stud

y is

not

incl

uded

in th

e su

mm

ary

2 As Dror (2017) notes, the development of this taxonomy began in a paper in 2009 (Dror 2009) and was further developed in a 2014 paper (Stoel et al. 2014), with additional sources of bias added subsequently (in Dror 2015, and Zapf & Dror 2017).

Rese

arch

focu

s

Aut

hors

(Yea

r)Lo

catio

nPa

rtici

pant

saSa

mpl

e si

zeH

uman

nat

ure

Envi

ronm

ent a

nd

cultu

reIn

divi

dual

ch

arac

teris

tics

Cas

e-

spec

ific

Inte

rven

tion

Was

tell

et a

l. (2

012)

Aus

tralia

Stud

ents

or c

omm

unity

Stud

y 1:

50;

Stu

dy

2: 4

4H

ypot

hesi

s co

nfirm

atio

n

Tabl

e 1

(con

tinue

d)


1 3

bias, sometimes colloquially referred to as “tunnel vision,” denotes selective seeking, recalling, weighting, and/or inter-preting information in ways that support existing beliefs, expectations, or hypotheses, while simultaneously avoiding or minimizing inconsistent or contradictory information (Nickerson 1998; Findley 2012). Some authors in this col-lection of studies used other terms to describe this concept or elements of it, including “context effects,” the term used by Charman et al. (2015) to describe when “a preexisting belief affects the subsequent interpretation of evidence” (p. 214), and asymmetrical skepticism (Ask & Granhag 2007b; Marksteiner et al. 2010).

Eight studies with law enforcement personnel (Ask & Granhag 2007b; Ask et al. 2008; Charman et al. 2017; Ditrich 2015; Groenendaal & Helsloot 2015; Marksteiner et al. 2010; Rassin 2010; Wallace 2015) examined aspects of confirmation bias; one addressed the distinct but related phenomenon of groupthink (Kerstholt & Eikelboom 2007). The importance of this issue was demonstrated by a survey of an unspecified number of professional crime scene offic-ers conducted by Ditrich (2015), asking for their opinions

about the relative frequency and severity of various cogni-tive errors that could potentially negatively affect a crimi-nal investigation; based on their experiences, respondents highlighted confirmation bias (as well as overestimating the validity of partial information and shifting the burden of proof to the suspect). The other studies within this group used experimental designs to assess police officers’ evalua-tion of evidence. Charman et al. (2017) reported that police officers’ initial beliefs about the innocence or guilt of a sus-pect in a fictional criminal case predicted their evaluation of subsequent ambiguous evidence, which in turn predicted their final beliefs about the suspect’s innocence or guilt. This is not the only study to demonstrate that, like the rest of us, police officers are susceptible to confirmation bias. Ask and colleagues (2008) found that police recruits discredited or supported the same exact evidence (“the viewing distance of 10 m makes the witness identification unreliable” versus “from 10 m one ought to see what a person looks like”) depending on whether it was consistent or inconsistent with their hypothesis of a suspect’s guilt. Ask and Granhag (2007b) found that when experienced criminal investigators

c

Fig. 1 Organizational framework for case evaluation studies, adapted from Dror’s (2017) taxonomy of different sources of potential bias that may cognitively contaminate forensic observations and conclu-

sions. The specific factors listed in this pyramid are those that were examined in the collection of studies in the present literature review


1 3

read a vignette that implied a suspect’s guilt (but left room for an alternative explanation), they rated subsequent guilt-consistent evidence as more credible and reliable than evi-dence that was inconsistent with their theory of guilt; similar results were seen in a study of police officers, district attor-neys, and judges by Rassin (2010).

Marksteiner et al. (2010) investigated the motivational underpinnings of this type of asymmetrical skepticism among police trainees, asking whether it is driven by a desire to reconcile inconsistent information with prior beliefs or by the goal of case closure, and encountered mixed results. The group who initially hypothesized guilt reacted as expected, rating subsequent incriminating evidence as more reliable, but in the group whose initial hypothesis was innocence, there was no difference in the way that they rated additional consistent or inconsistent information. Wallace (2015) found that the order in which evidence was presented influenced guilt beliefs. When police officers encountered exculpatory evidence prior to inculpatory evidence, guilt belief scores decreased, suggesting their final decisions were influenced by their initial impressions. Kerstholt and Eikelboom (2007) describe how teams tend to converge on one interpretation, and once such an interpretation is adopted, individual mem-bers are less able to examine underlying assumptions criti-cally. They asked independent crime analysts to evaluate a realistic criminal investigation with fresh eyes and found that they were demonstrably influenced when they were aware of the investigative team’s existing working hypothesis.

Studies in student and general populations examining confirmation bias and other aspects of human cognition (Ask et al. 2011b; Charman et al. 2015; Eerland et al. 2012; Eerland & Rassin 2012; Greenspan & Surich 2016; O’Brien 2007; 2009; Price & Dahl 2014; Rassin et al. 2010; Simon et al. 2004; Wastell et al. 2012) reported similar patterns to those described above with police participants. O’Brien (2007; 2009) found that students who named a suspect early in a mock criminal investigation were biased towards con-firming that person’s guilt as the investigation continued. O’Brien measured memory for hypothesis-consistent ver-sus hypothesis-inconsistent information, interpretation of ambiguous evidence, participants’ decisions to select lines of inquiry into the suspect or an alternative, and ultimate opin-ions about guilt or innocence. In a novel virtual crime scene investigation, Wastell et al. (2012) found that all students (those who ultimately chose the predetermined “correct” suspect from the multiple available people of interest and those who chose incorrectly) sought more chosen-suspect-consistent information during the exercise. However, those who were ultimately unsuccessful (i.e., chose the wrong person) spent more time in a virtual workspace (a measure of the importance placed on potential evidence) after access-ing confirmatory information. They also found that students who settled on a suspect early in the exercise—measured

by prompts throughout the virtual investigation—were com-paratively unsuccessful.

Other psychological phenomena such as recency effects (i.e., our ease of recalling information presented at the end of a list relative to information presented at the beginning or middle) and the feature positive effect (i.e., our tendency to generally attune to presence more than absence) were also examined in studies with student or general population par-ticipants. Price and Dahl (2014) explored evidence presenta-tion order and found that under certain circumstances, evi-dence presented later in an investigation had a greater impact on student participant decision-making in a mock criminal investigation. Charman and colleagues also found order of evidence presentation influenced ratings of strength of evi-dence and likelihood of guilt in their 2015 study of evidence integration with student participants. These results appear to provide evidence against the presence of confirmation bias, but recency effects still demonstrate the influence of human factors as, arguably, the order in which one learns about various pieces of evidence -whether first or last- should not impact interpretation. Several research teams found that a positive eyewitness identification is seen as more cred-ible than a failure to identify someone (Price & Dhal 2014, p.147) and the presence of fingerprints—as opposed to a lack of fingerprints—is more readily remembered and used to make decisions about a criminal case (Eerland et al. 2012; Eerland & Rassin 2012), even though the absence of evi-dence can also be diagnostic. Other researchers highlighted our psychic discomfort with cognitive dissonance (Ask et al. 2011b) and our tendency to reconcile ambiguity and artifi-cially impose consistency in a criminal case by engaging in “bidirectional coherence-based reasoning” (Simon et al. 2004; Greenspan & Surich 2016).

Environment and Culture

The three “environment and culture” studies with police per-sonnel (Ask & Granhag 2007b; Ask et al. 2011a; Fahsing & Ask 2016) revealed the ways in which external factors can influence an investigation. For instance, type of train-ing appears to impact the ability to generate a variety of relevant hypotheses and actions in an investigation. Eng-lish and Norwegian investigators are trained and performed differently when faced with semi-fictitious crime vignettes (Fahsing & Ask 2016). Organizational culture can impact the integrity of an investigation as well. Ask and colleagues (2011a) concluded that a focus on efficiency—as opposed to thoroughness—produces more cursory processing among police participants, which could be detrimental to the accu-rate assessment of evidence found later in an investigation. Ask and Granhag (2007b) observed that induced time pres-sure influenced officers’ decision-making, creating a higher


1 3

tendency to stick with initial beliefs and a lower tendency to be influenced by the evidence presented.

Individual Characteristics

Seven “individual characteristics” studies with police per-sonnel (Ask & Granhag 2005; 2007a; Dando & Ormerod 2017; Fahsing & Ask 2016; 2017; Kerstholt & Eikelboom 2007; Wallace 2015) plus two studies with student popula-tions (Rassin 2010, 2018a) examined ways in which personal attributes can influence an investigation. Varying amounts of professional experience may matter when it comes to assessments of potential criminal cases and assumptions about guilt. For instance, police recruits appear to have a strong tendency toward criminal—as opposed to non-crimi-nal—explanations for an ambiguous situation like a person’s disappearance (Fahsing & Ask 2017) and less experienced recruits show more suspicion than seasoned investigators (Wallace 2015). In a departure from the typical mock crime vignette method, Dando and Ormerod (2017) reviewed police decision logs (used for recording and justifying deci-sions made during serious crime investigations) and found that senior officers generated more hypotheses early in an investigation, and switched between considering different hypotheses both early and late in an investigation (suggest-ing a willingness to entertain alternative theories) compared with inexperienced investigators. An experimental study, however, found that professional crime analyst experience level (mean 7 months versus 7 years) was not related to case evaluation decisions and did not protect against knowledge of prior interpretations of the evidence influencing conclu-sions (Kerstholt & Eikelboom 2007).

Two studies examined differences in reasoning skills in relation to the evaluation of evidence. Fahsing and Ask (2017) found that police recruits’ deductive and inductive reasoning skills were not associated with performance on an investigative reasoning task. In contrast, in a study with undergraduate students, accuracy of decision-making regarding guilt or innocence in two case scenarios was asso-ciated with differences in logical reasoning abilities as meas-ured by a test adapted from the Wason Card Selection Test (Rassin 2018a).

Ask and Granhag (2005) found inconsistent results in a study of police officers’ dispositional need for cognitive closure and the effect on criminal investigations. Those with a high need for cognitive closure (measured with an estab-lished scale) were less likely to acknowledge inconsistencies in case materials when those materials contained a potential motive for the suspect, but were more likely to acknowledge inconsistencies when made aware of the possibility of an alternative perpetrator. In a replication study with under-graduate students, Ask & Granhag (2005) found that ini-tial hypotheses significantly affected subsequent evidence

interpretation, but found no interaction with individual need for cognitive closure. Students who were aware of an alter-native suspect (compared with those aware of a potential motive for the prime suspect) were simply less likely to eval-uate subsequent information as evidence supporting guilt.

In another study, when Ask and Granhag (2007a) induced negative emotions in police officers and then asked them to make judgments about a criminal case, sad participants were better able to substantively process the consistency of evidence or lack thereof, whereas angry participants used heuristic processing.

Case‑Specific

Four studies of police personnel (Ask et al. 2008; Fahsing & Ask 2016; 2017; Wallace 2015), one using police records (Dando & Omerod 2017), and three studies of student popu-lations (Ask et al. 2011b; O’Brien 2007; 2009; Rassin et al. 2010) examined “case-specific” and evidence-specific fac-tors. In a study of police officers, Ask and colleagues (2008) showed that the perceived reliability of some types of evi-dence (DNA versus photographs versus witnesses) is more malleable than others; similar results pertaining to DNA ver-sus witness evidence were found in a study of law students (Ask et al. 2011b).

Fahsing and Ask (2016) found that police recruits who were presented with a scenario including a clear “tipping point” (an arrest) did not actually produce significantly fewer hypotheses than those who were not presented with a tipping point (though they acknowledge that the manipulation—one sentence embedded in a case file—may not have been an ecologically valid one). In a subsequent study with police recruits, the presence of a tipping point resulted in fewer generated hypotheses, but the difference was not statistically significant (Fahsing & Ask 2017).

Other studies using law students (Rassin et al. 2010) or undergraduate students (O’Brien 2007) examined the influ-ence of crime severity on decision-making. Rassin et al. (2010) observed that the affinity for incriminating evidence increases with crime severity, but in one of O’Brien’s (2007) studies, crime severity did not have a demonstrable impact on confirmation bias.

Interventions

Taken together, this body of work demonstrates vulnerabili-ties in criminal investigations. Some researchers have sug-gested theoretically supported solutions to protect against these vulnerabilities, such as gathering facts rather than building a case (Wallace 2015) or institutionalizing the role of a “contrarian” in a criminal investigation (MacFarlane 2008). Few studies have tested and evaluated these potential remedies, however. Testing is an essential prerequisite to


1 3

any advocacy for policy changes because theoretically sound interventions may not, in fact, have the intended effect when applied (e.g., see below for a description of O’Brien’s work testing multiple interventions with differing results).

Four studies have examined various intervention approaches with police departments or investigators (Groenendaal & Helsloot 2015; Jones et al. 2008; Rassin 2018b; Salet & Terpstra 2014). Jones et al. (2008) created a tool that helped an experimental group of investigators produce higher quality reviews of a closed murder case than those working without the aid of the review tool. Their arti-cle provides an appendix with “categories used in the review tool” (e.g., crime scene management, house-to-house enquir-ies, community involvement) but lacks a detailed description of the tool itself and the outcome measures. Importantly, the authors raise the possibility that a review tool like this may improve how officers think through a case because of the structure or content of the tool or it may succeed by simply slowing them down so they can think more criti-cally and thoroughly. Another approach that shows promise in reducing tunnel vision is using a pen and paper tool to prompt investigators to consider how well the same evidence supports different hypotheses (Rassin 2018b). In a study of actual case files, supplemented with interviews, Salet and Terpstra (2014) explored “contrarians” and found that there are real-world challenges to the position’s efficacy (e.g., per-sonal desire to be a criminal investigator, desire for solidarity with colleagues) and considerable variability in the way con-trarians approach their work, with some opting for closeness to an investigation and others opting for distance; individu-als also embraced different roles (e.g., supervisor, devil’s advocate, focus on procedure). The researchers concluded that, in practice, these contrarians appear to have exerted subtle influence on investigations but there is no evidence of a radical change in case trajectory. Similarly, members of criminal investigation teams in the Netherlands reported that, in practice, designated devil’s advocates tend to provide sound advice but do not fundamentally change the course of investigations (Groenendaal & Helsloot 2015). Groenendaal and Helsloot describe the development and implementation of the Criminal Investigation Reinforcement Programme in the Netherlands, which was prompted by a national reckon-ing stemming from a widely publicized wrongful conviction. The program included new policies aimed at, among other things, reducing tunnel vision (including the use of devil’s advocates, structured decision-making around “hypotheses and scenarios,” and professionalized, permanent “Command Core Teams” dedicated to major crimes). This deliberate intervention provided an opportunity for researchers to inter-view investigators who were directly impacted by the new policies. Groenendaal and Helsloot conclude that the main effect of this intervention was an increased awareness about the potential problem of tunnel vision, and they focus on an

unresolved a tension between “efficacy” (more convictions) and “precaution” (minimizing wrongful convictions). Their work underscores the importance of collecting criminal legal system data, as interveiwees reported their experiences and impressions but could not report whether more correct con-victions had been obtained or more wrongful convictions avoided.

Other studies have examined various intervention ideas with student populations (Haas et al. 2015; O’Brien 2007; 2009). Haas et al. (2015) found that using a checklist tool to evaluate evidence appears to improve students’ abduc-tive reasoning and reduce confirmation bias. O’Brien (2007; 2009) found that orienting participants to being accountable for good process versus outcome had no impact, and that when participants expected to have to persuade someone of their hypothesis, this anticipation actually worsened bias. More promisingly, she discovered that participants who were asked to name a suspect early in an investigation, but were then told to consider how their selected suspect could be innocent and then generate counter-arguments, displayed less confirmation bias across a variety of measures (they looked the same as those who did not name a suspect early). But another approach—asking participants to generate two additional alternative suspects—was not effective (these participants showed the same amount of bias as those who identified just one suspect).

Discussion

Zalman and Larson (2016) have observed “the failure of innocence movement advocates, activists, and scholars to view the entirety of police investigation as a potential source of wrongful convictions, as opposed to exploring arguably more discrete police processes (e.g., eyewitness identifica-tion, interrogation, handling informants)” (p.3). While the thorough examination of these discrete processes has led to a better understanding of risk factors and, ultimately, reforms in police practices (e.g., see the Department of Justice 2017 guidelines for best practices with eyewitnesses), a recent shift towards viewing wrongful convictions from a “sentinel events”3 perspective advances the conversation around these criminal justice system failures (Doyle 2012; 2014; Rossmo & Pollock 2019).

This literature review has identified a body of research that lends support to this holistic perspective. The stud-ies reviewed here address a constellation of concepts that

3 According to the National Institute of Justice (2017), a senti-nel event is a significant negative outcome that (1) signals underly-ing weaknesses in the system or process, (2) is likely the result of compound errors, and (3) may provide, if properly analyzed and addressed, important keys to strengthen the system and prevent future adverse outcomes.


1 3

demonstrate how the human element—including universal psychological tendencies, predictable responses to situ-ational and organizational factors, personal factors, and char-acteristics of the crime itself—can unintentionally under-mine truth-seeking in the complex evidence integration process. Some concepts are addressed by one study, some are addressed by several, and some studies explored multiple variables (e.g., demonstrating the existence of confirmation bias and measuring how level of professional experience plays a role).

Several contemporary studies have demonstrated the existence of confirmation bias in police officers within the context of criminal investigations. Other psychological phenomena have not been examined in police populations but have been examined in student or general populations using study materials designed to assess the interpretation of criminal case evidence and decision-making. This collection of studies also investigates the role of environmental factors that may be specific to a department or organization, char-acteristics of individual investigators, or of the specific case under review. At the environmental level, type of training and organizational customs were influential and are promis-ing areas for further research as these factors are within the control of police departments and can be modified. With respect to individual characteristics, a better understanding of advantageous dispositional tendencies and what is gained by professional experience, as well as the unique risks of expertise, could lead to better recruitment and training meth-ods. Case-specific factors are outside the control of inves-tigators, but awareness of factors that pose a greater risk for bias could serve as an alert and future research could identify ways to use this information in practice (see also Rossmo & Pollock 2019 for an in-depth discussion of “risk recipes”).

Charman and colleagues (2017) present a particularly interesting illustration of the way in which a criminal case is not merely the sum of its parts. In this study, the research-ers presented law enforcement officers with exonerating, incriminating, or neutral DNA or eyewitness evidence, col-lected initial beliefs about guilt, asked participants to evalu-ate a variety of other ambiguous evidence (alibi, composite sketch, handwriting comparison, and informant information that could be reasonably interpreted in different ways), and then provide a final rating of guilt. As hypothesized, the researchers found those who were primed with incriminating evidence at the beginning were more likely to believe the suspect guilty at the end. However, even those who initially received exonerating information and initially rated the like-lihood of suspect guilt as relatively low ended up increasing their guilt rating after reviewing the other ambiguous evi-dence. It appears that the cumulative effect of ambiguous evidence tilted the scales towards guilt. This unexpected outcome underscores the value of understanding how the

4 As Snook and Cullen (2008) assert, “it is unrealistic to expect police officers to investigate all possible suspects, collect evidence on all of those suspects, explore all possible avenues concerning the circumstances surrounding a crime, search for disconfirming and confirming evidence of guilt for every suspect, and integrate all of this information” (p. 72). Dando and Ormerod (2017) illustrate this real-world complexity when they describe an investigation that was delayed because a call for tips led to a flood of false leads, suggest-ing that more information is not always better. Further, though it addresses procedural justice in street policing rather than evidence integration in a criminal investigation (and thus was not included in this review), Owens et al. (2018) provide an example of a field study, complete with published scripts. Recognizing the automated think-ing and behavior that comes with job experience, these researchers tested an intervention to reduce the number of incidents resolved with arrests and use of force by implementing a training program aimed at encouraging beat officers to think more slowly and deliberately dur-ing routine encounters; they also assessed the cost of this intervention in the police department.

totality of evidence in a criminal case is evaluated, and has implications for the legal doctrine of “harmless error” rooted in assumptions of evidentiary independence (e.g., Hasel & Kassin 2009).

Consistently incorporating control groups into future study designs and including complete stimulus materials in future publications could build on this foundation. This would help future researchers fully interpret and replicate study results and would assist in determining what elements of intervention strategies work. Since the majority of these studies were conducted in Europe, it would be worthwhile to explore whether or not these results can be replicated in the USA, given the similarities and differences in our crimi-nal justice systems and the variety of approaches used to select and train detectives across police departments. Finally, valuable future research will move beyond the demonstra-tion of these human vulnerabilities and will design and test strategies to mitigate them in the complex real world.4 Vignettes and mock-investigations are clever ways of stud-ying criminal investigations, but it is worth remembering that these approaches cannot fully capture the dynamics of a real criminal investigation. Collaboration between academic researchers and criminal investigators could generate robust expansions of this work.

Evidence evaluation and synthesis in criminal investiga-tions is, of course, just one part of a larger legal process. In addition to police, defense attorneys, prosecutors, and judges have powerful roles in determining case outcomes, especially in a system that is heavily reliant on plea bargain-ing. Critically addressing the potential influence of cognitive biases throughout this system, and promoting and imple-menting proven, practical protections against these tenden-cies will advance accuracy and justice.


1 3

App

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Str

eng

th o

f ev

iden

ce

Consi

sten

t w

itnes

ses

4.7

6 ±

2.2

2

5.3

6 ±

2.3

4

Inco

nsi

sten

t w

itnes

ses

5

.20

± 2

.01

3

.60

± 1

.84

(p <

1.0

)

(p

< 0

.05)


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

N=

49 c

rimin

al in

vesti

gato

rs, m

ean

expe

rienc

e 10

ye

ars,

Swed

en•

Expl

anat

ory

Mea

sure

s: N

eed

for c

ogni

tive

clos

ure

indu

ced

by ti

me

pres

sure

(ass

ignm

ent t

o on

e of

two

grou

ps; u

nlim

ited

time

to c

ompl

ete

task

or l

imite

d to

20

min

utes

, whi

ch w

as

less

than

the

med

ian

time

the

parti

cipa

nts i

n th

e co

mpa

rison

gr

oup

took

); ca

se sc

enar

io v

ersi

on (r

ando

m a

ssig

nmen

t not

sp

ecifi

ed).

Low

er ra

tings

for w

itnes

s rel

iabi

lity,

witn

essi

ng c

ondi

tions

, ret

entio

n in

terv

al, a

nd w

eigh

t of w

itnes

s evi

denc

e fo

r witn

ess w

ho p

rovi

ded

evid

ence

con

tradi

ctin

g (e

xone

ratin

g), a

s opp

osed

to su

ppor

ting,

the

susp

ect’s

gui

lt (in

crim

inat

ing)

:

Hum

an N

atur

e; E

nviro

nmen

t and

Cul

ture

• Pr

imar

y O

utco

me

Mea

sure

s: P

re- a

nd p

ost-e

yew

itnes

s evi

-de

nce

ratin

gs o

f gui

lt or

inno

cenc

e (d

icho

tom

ous)

, con

fiden

ce,

stren

gth

of e

vide

nce,

ade

quac

y of

evi

denc

e fo

r pro

secu

tion;

ra

tings

of w

itnes

s cre

dibi

lity,

con

ditio

ns fo

r mak

ing

relia

ble

obse

rvat

ions

, im

pact

of w

itnes

s em

otio

nal r

eact

ion,

effe

ct

of 7

-day

del

ay in

witn

ess r

epor

t to

polic

e, w

eigh

t of w

itnes

s ev

iden

ce in

rela

tion

to o

ther

evi

denc

e, a

gree

men

t of w

itnes

s ev

iden

ce w

ith o

ther

evi

denc

e (a

ll 9-

poin

t Lik

ert s

cale

s).

No

sign

ifica

nt d

iffer

ence

s wer

e se

en in

ratin

gs o

f witn

ess c

redi

bilit

y or

im

pact

of w

itnes

s em

otio

ns, t

houg

h th

e pa

ttern

s em

erge

d in

the

sam

e di

rect

ion.

Littl

e di

ffere

nce

in a

sym

met

rical

skep

ticis

m re

sults

whe

n co

mpa

ring

low

- and

hig

h-tim

e pr

essu

re g

roup

s, th

ough

the

grea

test

resp

onse

to

info

rmat

ion

conv

eyed

in th

e w

itnes

s sta

tem

ent w

as fo

und

in th

e lo

w-

time

pres

sure

con

ditio

n.A

sk, R

ebel

ius,

and

Gra

nhag

(200

8)•

Mat

eria

ls: H

omic

ide

case

c des

crip

tion

sugg

estin

g gu

ilt o

f a

susp

ect a

ppre

hend

ed n

ear t

he sc

ene

+ o

ne a

dditi

onal

type

of

evid

ence

(DN

A, e

yew

itnes

s, ph

oto)

that

was

eith

er c

onsi

stent

w

ith o

r inc

onsi

stent

with

a g

uilty

con

clus

ion.

Resu

lts p

rovi

de e

vide

nce

for a

sym

met

rical

skep

ticis

m in

crim

inal

in

vesti

gatio

ns.

N=

117

polic

e tra

inee

s, Sw

eden

• Ex

plan

ator

y M

easu

res:

Typ

e of

evi

denc

e (r

ando

m a

ssig

n-m

ent);

con

siste

nt o

r inc

onsi

stent

evi

denc

e ve

rsio

n (r

ando

m

assi

gnm

ent).

Hig

her r

atin

g of

relia

bilit

y fo

r evi

denc

e co

nsist

ent w

ith g

uilt

com

pare

d to

evi

denc

e in

cons

isten

t with

gui

lt ac

ross

type

s of e

vide

nce

in th

e ca

se:

Hum

an N

atur

e; C

ase-

Spec

ific

• Pr

imar

y O

utco

me

Mea

sure

s: R

atin

gs o

f gui

lt pr

obab

ility

, str

engt

h of

evi

denc

e be

fore

and

afte

r rev

iew

of a

dditi

onal

ev

iden

ce, r

atin

gs o

f rel

iabi

lity

of th

e sp

ecifi

c ev

iden

ce p

ro-

vide

d an

d of

the

relia

bilit

y of

that

evi

denc

e ty

pe in

gen

eral

(all

9-po

int L

iker

t sca

les)

.

Type

of E

vide

nce:

DN

A e

vide

nce

rate

d hi

gher

relia

bilit

y th

an p

hoto

or

witn

ess (

p <

0.0

1); n

o di

ffere

nce

betw

een

phot

o an

d w

itnes

s

Sim

ilar r

esul

ts w

ere

seen

with

ratin

gs o

f evi

denc

e in

gen

eral

.

[Mea

n±

SD

]

Incr

imin

atin

gE

xo

ner

atin

g

Wit

nes

s re

liab

ilit

y6.3

2±

1.5

35.4

0±

1.5

4

Wit

nes

sin

gco

nd

itio

ns

6.2

1±

1.6

55

.20

±1.8

8

Ret

enti

on

inte

rval

5.4

2±

1.2

24

.80

±1

.70

Wei

gh

t o

f ev

iden

ce5

.00

±2

.19

4.1

8±

1.6

3

[Mea

n±

SD

]

Consi

sten

t In

consi

sten

t

DN

A7.5

00

.74

7.2

7±

1.4

9

Pho

to6.6

5±

1.0

75.6

0±

1.8

5

Wit

nes

s7

.00

±1

.03

4.9

0±

1.1

8

DNA

7.41

±1.09

Photo

6.16

±1.56

Witn

ess

5.81

±1.52


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

Ask

, Gra

nhag

, and

Reb

eliu

s (20

11a)

• M

ater

ials

: Giv

en d

escr

iptio

n of

a “

good

inve

stiga

tor”

that

em

phas

ized

effi

cien

cy, t

horo

ughn

ess,

or n

eith

er; t

hen

give

n as

saul

t cas

eb d

escr

iptio

n su

gges

ting

the

vict

im’s

fath

er w

as

guilt

y +

two

witn

ess s

tate

men

ts. S

econ

d w

itnes

s sta

tem

ent

was

eith

er c

onsi

stent

or i

ncon

siste

nt w

ith th

e hy

poth

esis

that

th

e vi

ctim

’s fa

ther

was

resp

onsi

ble.

Resu

lts p

rovi

de e

vide

nce

for s

alie

nt so

cial

nor

ms i

nflue

ncin

g in

form

a-tio

n pr

oces

sing

in c

rimin

al in

vesti

gatio

ns.

N=

104

crim

inal

inve

stiga

tors

, mea

n ex

perie

nce

21

year

s, Sw

eden

• Ex

plan

ator

y M

easu

res:

Goa

l act

ivat

ion

thro

ugh

“goo

d in

vesti

gato

r” d

efini

tion

emph

asiz

ing

effici

ency

, tho

roug

hnes

s, or

nei

ther

/con

trol (

rand

om a

ssig

nmen

t); w

itnes

s sta

tem

ents

ve

rsio

n (r

ando

m a

ssig

nmen

t).

Effici

ency

ver

sus t

horo

ughn

ess a

ssoc

iate

d w

ith c

ompo

site

ratin

g of

gu

ilt, w

ith in

tera

ctio

n by

type

of w

itnes

s evi

denc

e; g

uilt

ratin

gs in

the

thor

ough

ness

gro

up w

ere

mos

t infl

uenc

ed:

Envi

ronm

ent a

nd C

ultu

re•

Prim

ary

Out

com

e M

easu

res:

Tas

k co

mpl

etio

n sp

eed

(rel

ativ

e to

oth

er p

artic

ipan

ts),

ratin

gs o

f gui

lt pr

obab

ility

and

stre

ngth

of

evi

denc

e (1

to 7

Lik

ert s

cale

s), c

ombi

ned

into

a c

ompo

site

sc

ore,

ratin

gs o

f the

ir ow

n ca

se p

roce

ssin

g w

ith re

spec

t to

judg

men

t spo

ntan

eity

, cog

nitiv

e eff

ort,

diffi

culty

dec

idin

g gu

ilt, a

nd c

onfid

ence

(1 to

7 L

iker

t sca

les)

.C

harm

an, K

avet

ski a

nd M

uelle

r (20

17)

• M

ater

ials

: Com

pute

r-adm

inist

ered

hom

icid

e ca

se d

escr

ip-

tion

with

eith

er D

NA

or e

yew

itnes

s evi

denc

e th

at w

as e

ither

in

crim

inat

ing,

exo

nera

ting

or n

eutra

l. A

fter m

akin

g an

initi

al

ratin

g of

like

lihoo

d of

gui

lt, a

ll pa

rtici

pant

s rev

iew

ed a

ddi-

tiona

l am

bigu

ous a

libi,

faci

al c

ompo

site

, han

dwrit

ing,

and

in

form

ant e

vide

nce

in a

rand

omiz

ed o

rder

.

Resu

lts p

rovi

de e

vide

nce

of c

onfir

mat

ion

bias

in e

valu

atio

n of

am

bigu

-ou

s crim

inal

evi

denc

e.

N=

89 p

olic

e offi

cers

, mea

n ex

perie

nce

20 y

ears

, U

nite

d St

ates

• Ex

plan

ator

y M

easu

res:

Typ

e of

evi

denc

e (D

NA

or e

yew

it-ne

ss) a

nd in

crim

inat

ing,

exo

nera

ting,

or n

eutra

l nat

ure

of

evid

ence

(ran

dom

ass

ignm

ent).

Inte

ract

ion

betw

een

type

of e

vide

nce

and

its in

terp

reta

tion

– hi

gher

ini-

tial r

atin

gs o

f gui

lt w

ith in

crim

inat

ing

DN

A e

vide

nce

com

pare

d w

ith

incr

imin

atin

g ey

ewitn

ess e

vide

nce;

low

er in

itial

ratin

gs o

f gui

lt w

ith

exon

erat

ing

DN

A c

ompa

red

with

exo

nera

ting

eyew

itnes

s evi

denc

e:H

uman

Nat

ure

• Pr

imar

y O

utco

me

Mea

sure

s: In

itial

ratin

gs o

f pro

babl

e gu

ilt

(1 to

100

scal

e) a

fter r

evie

win

g ca

se d

escr

iptio

n; ra

tings

of

eac

h ad

ditio

nal t

ype

of e

vide

nce

(1 to

7 L

iker

t sca

le fo

r str

engt

h of

alib

i; 1

to 1

00 sc

ale

for s

imila

rity

of fa

cial

com

pos-

ite to

susp

ect,

sim

ilarit

y of

han

dwrit

ing

to su

spec

t, th

e ex

tent

to

whi

ch in

form

ant e

vide

nce

impl

icat

ed su

spec

t); fi

nal r

atin

gs

of p

roba

ble

guilt

(1 to

100

scal

e) a

fter r

evie

win

g al

l of t

he

addi

tiona

l evi

denc

e.St

reng

th o

f ini

tial g

uilt

belie

f infl

uenc

ed su

bseq

uent

eva

luat

ion

of e

vi-

denc

e, e

xcep

t for

alib

i stre

ngth

:

[β =

rela

tion

betw

een

initi

al g

uilt

belie

f and

evi

denc

e ev

alua

tion]

[Mea

n±

SD

]:

Incr

imin

atin

gE

xculp

ato

ry

Eff

icie

ncy

4.8

1±

0.8

44

.44

±1

.04

(p=

0.3

0)

Tho

roughnes

s5

.32

±0

.98

3.9

7±

1.2

0(p

<0.0

01

)

Contr

ol

5.1

9±

1.0

64

.14

±1

.10

(p<

0.0

5)

Init

ial

Pro

bab

le

[M

ean

± S

D]

Guil

t R

atin

g f

or:

DN

A E

vid

ence

Eyew

itness

Incr

imin

atin

g 79.4

± 2

6.8

5

2.3

± 2

4.0

Neu

tral

31

.7 ±

23

.2

2

9.9

± 1

9.5

Ex

on

erat

ing

12

.2 ±

21

.9 3

1.6

± 2

1.4

Stre

ngth

of i

nitia

l gui

lt be

lief i

nflu

ence

d su

bseq

uent

ev

alua

tion

of e

vide

nce,

exce

pt fo

r alib

i stre

ngth

:Co

mpo

site

simila

rity

β =

0.63

7, S

E=0.

075

(p <

0.0

01)

Han

dwrit

ing

simila

rity

β =

0.60

4, S

E=0.

075

(p<0

.001

)In

form

ant

β

= 0

.672

, SE=

0.07

0 (p

< 0

.001

)A

libi s

treng

th

β =

0.09

9, S

E=0.

114

(p =

0.3

9)

[β =

rela

tion

betw

een

initi

al g

uilt

belie

f and

evi

denc

e ev

alua

tion]


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

The

cum

ulat

ive

effec

t of a

mbi

guou

s evi

denc

e w

as to

incr

ease

per

cep-

tion

of g

uilt:

all

final

gui

lt ra

tings

wer

e hi

gher

than

initi

al g

uilt

ratin

gs,

exce

pt fo

r tho

se w

ho b

egan

with

incr

imin

atin

g D

NA

evi

denc

e, p

er-

haps

indi

catin

g a

ceili

ng e

ffect

:

Dan

do a

nd O

rmer

od (2

017)

• M

ater

ials

: Ran

dom

ly se

lect

ed d

ecis

ion

logs

from

two

polic

e fo

rces

in w

hich

ent

ries c

once

rned

a c

rime,

det

ectiv

es m

ade

clea

r a p

refe

renc

e of

pos

sibl

e ac

tion,

and

a re

ason

was

giv

en

to fo

llow

the

cour

se o

f act

ion.

Plo

tted

case

tim

elin

es n

otin

g w

hen

hypo

thes

es w

ere

gene

rate

d an

d te

sted.

Resu

lts su

gges

t tha

t use

of d

ecis

ion

logs

var

ies b

y ty

pe o

f cas

e an

d th

e offi

cer i

nvol

ved,

but

this

doc

umen

tatio

n re

veal

s diff

eren

ces i

n in

ves-

tigat

ive

deci

sion

-mak

ing

by p

rofe

ssio

nal e

xper

ienc

e le

vel t

hrou

ghou

t an

inve

stiga

tion.

N=

60 p

olic

e de

cisi

on lo

gs, U

nite

d K

ingd

om•

Expl

anat

ory

Mea

sure

s: P

olic

e offi

cer e

xper

ienc

e le

vel (

mea

n 10

ver

sus m

ean

2 ye

ars)

.Si

mila

r num

ber o

f log

ent

ries e

ach

wee

k by

exp

erie

nce

leve

l:

Indi

vidu

al C

hara

cter

istic

s; C

ase-

Spec

ific

• Pr

imar

y O

utco

me

Mea

sure

s: N

umbe

r of l

og e

ntrie

s, le

ngth

of

inve

stiga

tion;

ana

lyze

d nu

mbe

r of h

ypot

hese

s gen

erat

ed, n

um-

ber o

f evi

denc

e so

urce

s exa

min

ed to

supp

ort t

hese

hyp

oth-

eses

, and

ord

er in

whi

ch h

ypot

hese

s wer

e ge

nera

ted;

ratio

of

horiz

onta

l to

verti

cal a

ctiv

ity tr

ansi

tions

(ind

icat

ing

num

ber o

f hy

poth

eses

bei

ng e

xam

ined

: > 1

= m

ultip

le li

nes o

f inq

uiry

; <

1 =

“sa

tisfic

ing”

, or f

ocus

ing

on a

sing

le li

ne o

f inq

uiry

).

Num

ber o

f hyp

othe

ses g

ener

ated

was

hig

hest

in fi

rst q

uarti

le a

nd h

ighe

r fo

r mor

e ex

perie

nced

inve

stiga

tors

:

Mea

n nu

mbe

r of e

vide

nce

sour

ces o

pene

d w

as h

ighe

st in

the

begi

nnin

g of

the

inve

stiga

tion,

but

ther

e w

as li

ttle

diffe

renc

e by

exp

erie

nce

leve

l:

Expe

rienc

ed in

vesti

gato

rs e

xplo

red

mul

tiple

hyp

othe

ses i

n th

e be

gin-

ning

and

at t

he e

nd o

f the

inve

stiga

tion;

less

exp

erie

nced

inve

stiga

tors

fo

cuse

d on

a si

ngle

hyp

othe

sis t

hrou

ghou

t the

inve

stiga

tion:

Fin

al P

robab

le [

Mea

n ±

SD

]

Guil

t R

atin

g f

or:

DN

A E

vid

ence

Eyew

itness

Incr

imin

atin

g 78.4

± 1

4.9

62

.0 ±

23

.1

Neu

tral

53

.7 ±

23

.8

5

5.3

± 2

1.8

Ex

on

erat

ing

3

9.0

± 2

7.2

55

.2 ±

25

.3

[Mea

n ±

SD]:

Mor

e exp

erie

nced

8

.19

±4.

13Le

ss e

xper

ienc

ed

9.

62 ±

3.3

0

[p =

0.4

5]

Mea

n nu

mbe

r of h

ypot

hese

s Q1

Q2

Q3

Q4

Expe

rienc

e > 5

yea

rs

2

.84

1

.17

0.

79

0.5

5

Expe

rienc

e < 3

yea

rs

1

.38

0

.62

0.

51

0.8

2

Num

ber o

f evi

denc

e so

urce

s ope

ned

Q1

Q2

Q3

Q

4Ex

perie

nce >

5 y

ears

3.09

1

.25

2.

04

1.9

0

Expe

rienc

e < 3

yea

rs

3.

96

2.3

5

1.76

1

.20

Mea

n r

atio

of

hori

zonta

l to

vert

ical

act

ivit

y t

ransi

tio

ns

Q1 Q

2 Q

3

Q4

Ex

per

ien

ce >

5 y

ears

1

.29

0.8

6

0.7

7

1.3

2

Ex

per

ien

ce <

3 y

ears

0

.61

0.8

4

0.8

9

0.8

4

[> 1

= m

ult

iple

lin

es o

f in

qu

iry;

< 1

= “

sati

sfic

ing”,

or

focu

sing o

n a

sin

gle

lin

e o

f in

qu

iry]


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

Ditr

ich

(201

5)•

Mat

eria

ls: L

ist o

f cog

nitiv

e er

rors

ada

pted

from

med

ical

lit

erat

ure

to th

e cr

imin

al ju

stice

con

text

, pre

sent

ed v

erba

lly.

An

“ins

ide

view

” fro

m e

xper

ienc

ed c

rime

scen

e offi

cers

sugg

este

d th

at th

e m

ost c

omm

on a

nd p

oten

tially

det

rimen

tal c

ogni

tive

erro

rs

incl

uded

con

firm

atio

n bi

as, a

ncho

ring,

and

shift

ing

the

burd

en o

f pr

oof f

rom

the

inve

stiga

tor t

o th

e su

spec

t.“s

mal

l” n

umbe

r of e

xper

ienc

ed c

rime

scen

e offi

cers

, A

ustri

a•

Expl

anat

ory

Mea

sure

s: N

ot a

pplic

able

.

Hum

an N

atur

e•

Prim

ary

Out

com

e M

easu

res:

Opi

nion

s abo

ut fr

eque

ncy

of a

ppea

ranc

e (5

-poi

nt L

iker

t sca

le fr

om “

neve

r” to

“ve

ry

ofte

n”),

as w

ell a

s con

cept

s sel

ecte

d as

hav

ing

the

stron

gest

adve

rse

effec

t in

prac

tice.

Fahs

ing

and

Ask

(201

6)•

Mat

eria

ls: T

wo

mis

sing

per

son

case

d des

crip

tions

that

did

or

did

not c

onta

in a

tipp

ing

poin

t (de

cisi

on to

arr

est a

par

ticul

ar

susp

ect),

ask

ed to

writ

e do

wn

inve

stiga

tive

hypo

thes

es a

nd

actio

ns to

be

take

n.

Pres

ence

of t

ippi

ng p

oint

was

not

ass

ocia

ted

with

gen

erat

ion

of h

ypot

h-es

es o

r act

ions

(“ca

se-s

peci

fic”)

, but

rese

arch

ers s

aw a

n in

tera

ctio

n be

twee

n ex

perie

nce

leve

l (“i

ndiv

idua

l cha

ract

erist

ics”

) and

type

of

train

ing

(“en

viro

nmen

t and

cul

ture

”).

N=

124

crim

e in

vesti

gato

rs, a

bout

50%

exp

erie

nced

an

d 50

% n

ovic

es, 6

3 fro

m N

orw

ay, 6

1 fro

m

Engl

and

• Ex

plan

ator

y M

easu

res:

Tip

ping

poi

nt, e

xper

ienc

e le

vel

(> 1

0 ye

ars a

s a d

etec

tive

or <

2 y

ears

as p

olic

e offi

cer w

ith

no d

etec

tive

wor

k), t

ype

of tr

aini

ng (b

ased

on

coun

try).

Trai

n-in

g in

Eng

land

: sta

ndar

dize

d fo

ur-s

tep

qual

ifica

tion

syste

m

for d

etec

tives

, com

preh

ensi

ve p

roce

dura

l gui

delin

es, d

etai

led

rout

ines

for s

yste

mat

ic re

view

s and

kno

wle

dge-

shar

ing,

ann

ual

refr

eshm

ent t

rain

ing.

Tra

inin

g in

Nor

way

: on-

the-

job-

lear

ning

, no

nat

ion-

wid

e pr

ogra

m o

r sta

ndar

dize

d re

quire

men

ts.

Envi

ronm

ent a

nd C

ultu

re; I

ndiv

idua

l Cha

ract

erist

ics;

C

ase-

Spec

ific

• Pr

imar

y O

utco

me

Mea

sure

s: P

ropo

rtion

of “

gold

stan

dard

” se

t of h

ypot

hese

s and

act

ions

gen

erat

ed (“

gold

stan

dard

” de

velo

ped

by e

xper

t pan

el o

f hom

icid

e in

vesti

gato

rs fr

om

Nor

way

and

Eng

land

; see

Fah

sing

and

Ask

, Jou

rnal

of I

nves

-tig

ativ

e Ps

ycho

logy

and

Offe

nder

Pro

filin

g, 1

0, 1

55-1

65, 2

013

for d

etai

ls).

Expe

rienc

ed E

nglis

h pa

rtici

pant

s out

perfo

rmed

exp

erie

nced

and

in

expe

rienc

ed N

orw

egia

n pa

rtici

pant

s, w

ho o

utpe

rform

ed in

expe

ri-en

ced

Engl

ish

parti

cipa

nts.

Expe

rienc

e le

vel w

as n

ot a

ssoc

iate

d w

ith

perfo

rman

ce a

mon

g N

orw

egia

n pa

rtici

pant

s.

Fahs

ing

and

Ask

(201

7)•

Mat

eria

ls: G

iven

cog

nitiv

e ap

titud

e te

st m

easu

ring

indu

ctiv

e an

d de

duct

ive

reas

onin

g sk

ills.

Then

giv

en tw

o m

issi

ng p

erso

n ca

sed

desc

riptio

ns th

at c

onta

ined

a ti

ppin

g po

int (

deci

sion

to

arre

st a

parti

cula

r sus

pect

) eith

er e

arly

or l

ate

in th

e vi

gnet

te

and

aske

d to

writ

e do

wn

inve

stiga

tive

hypo

thes

es a

nd a

ctio

ns

to b

e ta

ken.

Resu

lts su

gges

t tha

t ind

uctiv

e an

d de

duct

ive

reas

onin

g ap

titud

e do

es n

ot

pred

ict s

uper

ior c

rimin

al in

vesti

gatio

n sk

ills,

and

a ca

se ti

ppin

g po

int

(arr

est)

does

not

nec

essa

rily

lead

to c

lose

d-m

inde

dnes

s.

[Mea

n ±

SD

]:

Pro

po

rtio

n o

f G

ener

ated

Go

ld S

tan

dar

d

Hyp

oth

eses

A

ctio

ns

Engla

nd

Ex

per

ien

ced

0

.72

± 0

.18

0.7

3 ±

0.1

0

No

vic

es

0.2

8 ±

0.1

2

0

.39

± 0

.11

(p-v

alue)

(p

< 0

.00

1)

(p <

0.0

01)

No

rway

Ex

per

ien

ced

0

.45

± 0

.16

0.6

4 ±

0.1

2

No

vic

es

0.5

0 ±

0.2

0

0

.61

± 0

.12

(p-v

alu

e)

(

p =

0.9

9)

(p

= 0

.99)


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

N=

166

polic

e tra

inee

s, N

orw

ay•

Expl

anat

ory

Mea

sure

s: C

ogni

tive

reas

onin

g sk

ills (

indu

ctiv

e an

d de

duct

ive

reas

onin

g sc

ores

bas

ed o

n st

anda

rdiz

ed te

st),

loca

tion

of ti

ppin

g po

int.

Ove

rall,

par

ticip

ants

gen

erat

ed a

hig

her p

ropo

rtion

of c

rimin

al v

ersu

s no

n-cr

imin

al e

xpla

natio

ns fo

r the

eve

nts (

Mea

n ±

SD

: 46.

7% ±

13.

8 ve

rsus

19%

± 1

9.1)

.In

divi

dual

Cha

ract

erist

ics;

Cas

e-Sp

ecifi

c•

Prim

ary

Out

com

e M

easu

res:

Pro

porti

on o

f “go

ld st

anda

rd”

set o

f hyp

othe

ses a

nd a

ctio

ns g

ener

ated

(“go

ld st

anda

rd”

deve

lope

d by

exp

ert p

anel

of h

omic

ide

inve

stiga

tors

from

N

orw

ay a

nd U

nite

d K

ingd

om).

Mor

e hy

poth

eses

gen

erat

ed fo

r Cas

e A

(Mea

n ±

SD

49.

2 ±

20.

3) th

an

for C

ase

B (2

9.5

± 1

0.8)

, p >

0.0

01. B

ecau

se o

f thi

s diff

eren

ce, o

ther

an

alys

es w

ere

cond

ucte

d se

para

tely

for C

ase

A a

nd C

ase

B.

In re

gres

sion

ana

lyse

s, no

ass

ocia

tion

was

seen

bet

wee

n th

e nu

mbe

r of

“gol

d st

anda

rd”

hypo

thes

es g

ener

ated

in e

ither

var

iatio

n of

the

case

s an

d th

e in

duct

ive

reas

onin

g sc

ore

or d

educ

tive

reas

onin

g sc

ore:

Earli

er “

tippi

ng p

oint

” (a

rres

t) di

d no

t sig

nific

antly

dec

reas

e th

e nu

mbe

r of

“go

ld st

anda

rd”

hypo

thes

es g

ener

ated

, but

ther

e w

ere

trend

s in

that

di

rect

ion.

Gro

enen

daal

and

Hel

sloo

t (20

15)

• M

ater

ials

: Hist

oric

al re

cord

of “

the

Schi

edam

mer

Par

k m

urde

r” in

the

Net

herla

nds;

sem

i-stru

ctur

ed g

roup

inte

rvie

ws

with

lead

ers a

nd c

oord

inat

ors o

f Com

man

d C

ore

Team

s fro

m

polic

e fo

rces

acr

oss t

he c

ount

ry.

Nar

rativ

e de

scrip

tion

of p

olic

ies p

rodu

ced

in re

spon

se to

the

Schi

edam

-m

er P

ark

mur

der a

nd su

bseq

uent

Pos

thum

us C

omm

issi

on.

N=

60 m

embe

rs o

f Com

man

d C

ore

Team

s, N

ethe

r-la

nds

• In

terv

entio

n: C

rimin

al In

vesti

gatio

n Re

info

rcem

ent P

ro-

gram

me,

dev

elop

ed a

nd im

plem

ente

d in

resp

onse

to a

wid

ely

publ

iciz

ed w

rong

ful c

onvi

ctio

n. C

rimin

al In

vesti

gatio

n Re

info

rcem

ent P

rogr

amm

e el

emen

ts in

clud

ed th

e cr

eatio

n of

Maj

or In

vesti

gatio

n Te

ams/

Com

man

d C

ore

Team

s aim

ed

at im

prov

ing

prof

essi

onal

izat

ion,

com

mun

icat

ion,

reco

rd-

keep

ing

arou

nd in

vesti

gativ

e de

cisi

on-m

akin

g, a

nd c

ritic

al

refle

ctio

n.

Inte

rvie

wee

s rep

orte

d th

at th

e M

ajor

Inve

stiga

tion

Team

mod

el

impr

oved

inve

stiga

tions

, but

did

not

kno

w w

heth

er m

ore

crim

es

wer

e so

lved

as a

resu

lt. T

hey

repo

rted

both

pro

s and

con

s to

perm

a-ne

nt p

ositi

ons,

reco

rd-k

eepi

ng a

bout

the

hypo

thes

es a

nd sc

enar

ios

deci

sion

-mak

ing

proc

ess.

They

felt

posi

tivel

y ab

out t

he d

evil’

s ad

voca

te sy

stem

but

foun

d th

at it

gen

eral

ly c

onfir

med

the

dire

ctio

n al

read

y be

ing

purs

ued

and

did

not i

dent

ify fl

aws.

They

repo

rted

that

, co

mpa

red

to p

revi

ous y

ears

, the

cul

ture

had

bec

ome

mor

e op

en.

Inte

rven

tion

• Pr

imar

y O

utco

me

Mea

sure

s: In

vesti

gato

rs’ s

elf-

repo

rted

expe

rienc

es w

ith v

ario

us e

lem

ents

of t

he n

ew P

rogr

amm

e,

as w

ell a

s “effi

cacy

” (i.

e., “

num

ber o

f sol

ved

crim

es”)

and

“p

reca

utio

n” (i

.e.,

“min

imis

atio

n of

the

chan

ce o

f wro

ngfu

l co

nvic

tion”

).

The

study

aut

hors

’ ide

ntifi

ed te

nsio

n be

twee

n th

e co

ncep

ts o

f effi

cacy

an

d pr

ecau

tion,

and

con

clud

ed th

at th

e m

ain

resu

lt of

the

Prog

ram

me

was

incr

ease

d aw

aren

ess a

bout

(but

no

mea

sura

ble

elim

inat

ion

of)

tunn

el v

isio

n.Ind

uct

ive

reas

on

ing

sco

re

Cas

e A

β

= 0

.04

SE

= 0

.16

, p

= 0

.78

Cas

e B

β

= 0

.04

, S

E =

0.0

8,

p =

0.6

6

Ded

uct

ive

reas

onin

g s

core

Cas

e A

β

= 0

.03

, S

E =

0.1

5,

p =

0.8

5

Cas

e B

β

= 0

.01

, S

E =

0.0

8,

p =

0.8

72


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

Jone

s et a

l. (2

008)

• M

ater

ials

: Giv

en fi

rst t

wo-

mon

ths-

wor

th o

f mat

eria

l of a

co

nclu

ded

mur

der i

nves

tigat

ion;

ask

ed to

revi

ew th

e in

vesti

ga-

tion

and

iden

tify

posi

tive

and

nega

tive

aspe

cts.

Expe

rimen

tal

grou

p gi

ven

Revi

ew T

ool (

deve

lope

d ba

sed

on a

lite

ratu

re

revi

ew a

nd in

acc

orda

nce

with

the

Ass

ocia

tion

of C

hief

Pol

ice

Offi

cers

(AC

PO) 2

006

Mur

der I

nves

tigat

ion

Man

ual (

MIM

))

prov

idin

g be

st pr

actic

es fo

r 31

cate

gorie

s of i

nves

tigat

ive

activ

ities

; con

trol g

roup

rece

ived

no

instr

uctio

ns b

ut c

ould

co

nsul

t AC

PO M

IM o

r oth

er m

ater

ials

.

Revi

ew T

ool p

rodu

ced

incr

ease

d qu

antit

y (a

mou

nt n

ot sp

ecifi

ed) a

nd

qual

ity (3

7% h

ighe

r) o

f inf

orm

atio

n, a

nd to

ok lo

nger

to c

ompl

ete

(app

roxi

mat

ely

33%

long

er).

N=

12 p

olic

e offi

cers

, 6 e

xper

ienc

ed a

nd 6

inex

peri-

ence

d in

vesti

gato

rs, U

nite

d K

ingd

om•

Inte

rven

tion:

Rev

iew

Too

l or c

ontro

l gro

up (r

ando

m a

ssig

n-m

ent);

offi

cer e

xper

ienc

e le

vel (

expe

rienc

ed =

seni

or in

vesti

-ga

ting

office

rs, i

nexp

erie

nced

= li

ttle

or n

o m

urde

r inv

estig

a-tio

n ex

perie

nce)

.

Exp

erie

nced

offi

cers

in b

oth

the

inte

rven

tion

and

cont

rol g

roup

s pro

-du

ced

high

er q

uant

ity a

nd q

ualit

y w

ork

Inte

rven

tion

• Pr

imar

y O

utco

me

Mea

sure

s: A

mou

nt o

f inf

orm

atio

n pr

o-du

ced

in e

ach

inve

stiga

tion

revi

ew; c

onte

nt a

naly

sis,

with

eac

h co

mm

ent r

ated

for u

sefu

lnes

s (1

to 7

Lik

ert s

cale

), am

ount

of

time

to c

ompl

ete

the

revi

ew.

Resu

lts sh

ow th

at b

oth

expe

rienc

e an

d th

e te

sted

Revi

ew T

ool h

elpe

d (th

ough

mec

hani

sm is

unc

lear

– R

evie

w T

ool m

ight

hel

p offi

cers

thin

k m

ore

thor

ough

ly a

nd c

ritic

ally

bec

ause

of t

he c

onte

nt a

nd st

ruct

ure

of

the

tool

, or m

ight

sim

ply

succ

eed

by sl

owin

g offi

cers

dow

n so

they

can

th

ink

mor

e th

orou

ghly

and

crit

ical

ly).

Ker

stho

lt an

d Ei

kelb

oom

, (20

07)

• M

ater

ials

: Tw

o re

alist

ic c

ase

scen

ario

s (C

ase

1: p

ossi

ble

sex

traffi

ckin

g, C

ase

2: d

isap

pear

ance

of a

you

ng w

oman

). H

alf o

f par

ticip

ants

rece

ived

a p

laus

ible

, but

not

the

mos

t lik

ely

(bas

ed o

n pi

lot t

estin

g), p

rior i

nter

pret

atio

n fo

r eac

h ca

se (C

ase

1: “

Rodr

ique

z” p

laye

d a

key

role

, Cas

e 2:

mis

sing

w

oman

’s fa

ther

pla

yed

role

in d

isap

pear

ance

).

Gro

upth

ink,

con

firm

atio

n bi

as d

emon

strat

ed. R

esul

ts sh

ow th

at a

naly

sts

who

are

priv

y to

an

inve

stiga

tive

team

’s w

orki

ng h

ypot

hesi

s will

su

gges

t tha

t hyp

othe

sis a

s the

mos

t lik

ely

at a

hig

her r

ate

than

ana

lysts

w

ho m

erel

y ge

t acc

ess t

o th

e fa

cts o

f the

cas

e bu

t no

prio

r int

erpr

eta-

tion.

Nov

ices

and

exp

erts

per

form

ed th

e sa

me

way

.

N=

38 c

rime

anal

ysts

, Net

herla

nds

• Ex

plan

ator

y M

easu

res:

Kno

wle

dge

of p

rior p

laus

ible

but

un

likel

y in

terp

reta

tion

or n

ot; e

xper

ienc

e le

vel (

mea

n 7

year

s ve

rsus

7 m

onth

s).

Hum

an N

atur

e; In

divi

dual

Cha

ract

erist

ics

• Pr

imar

y O

utco

me

Mea

sure

s: F

or C

ase

1, d

escr

iptio

n of

role

of

eac

h pe

rson

and

mos

t lik

ely

scen

ario

, ran

king

of s

ourc

es

of in

form

atio

n an

d im

porta

nce,

not

ed m

issi

ng in

form

atio

n,

and

sugg

estio

ns fo

r fur

ther

inve

stiga

tion.

For

Cas

e 2,

num

ber

and

type

of p

ossi

ble

expl

anat

ions

gen

erat

ed, c

oncl

usio

n ab

out

mos

t lik

ely

hypo

thes

is, s

ugge

stion

s for

furth

er in

vesti

gatio

n.

Cas

e 1:

Kno

wle

dge

of p

rior i

nter

pret

atio

n w

as a

ssoc

iate

d w

ith id

entif

y-in

g “R

odrig

uez”

as a

“ke

y pl

ayer

,” ev

iden

ce m

entio

ned

and

sugg

es-

tions

for f

urth

er in

vesti

gatio

n, b

ut n

ot w

ith ra

nkin

g of

info

rmat

ion

sour

ces,

or re

ports

of m

issi

ng in

form

atio

n. E

xper

ienc

e le

vel w

as n

ot

asso

ciat

ed w

ith d

ecis

ion-

mak

ing.

Pri

or

N

o P

rior

Inte

rpre

tati

on

In

terp

reta

tio

n

“Ro

dri

qu

ez =

key p

layer

”

56

%

25

% (

p=

0.0

6)

Men

tioned

info

rmat

ion

fro

m p

rio

r

inte

rpre

tati

on

89%

35%

(p

=0

.002

)

Rodri

quez-

furt

her

Inv

esti

gat

ion

78%

35%

(p

=0

.01

)


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

Cas

e 2:

Kno

wle

dge

of p

rior i

nter

pret

atio

n w

as a

ssoc

iate

d w

ith in

clus

ion

of fa

ther

scen

ario

as a

pos

sibl

e ex

plan

atio

n an

d as

the

mos

t lik

ely

expl

anat

ion,

and

as s

ugge

stion

for f

urth

er in

vesti

gatio

n, b

ut n

ot w

ith

num

ber o

f exp

lana

tions

gen

erat

ed. E

xper

ienc

e le

vel w

as n

ot a

ssoc

i-at

ed w

ith d

ecis

ion-

mak

ing.

Mar

kste

iner

et a

l. (2

010)

• M

ater

ials

: Com

pute

r-adm

inist

ered

hom

icid

e ca

sec d

escr

iptio

n su

gges

ting

guilt

or i

nnoc

ence

of s

uspe

ct, p

lus i

ncrim

inat

ing

or

exon

erat

ing

eyew

itnes

s evi

denc

e.

Asy

mm

etric

al sk

eptic

ism

am

ong

parti

cipa

nts w

ith a

gui

lty h

ypot

hesi

s:

Incr

imin

atin

g w

itnes

s evi

denc

e (c

ase-

spec

ific,

and

in g

ener

al) v

iew

ed

mos

t fav

orab

ly b

y th

ose

who

initi

ally

con

side

red

the

susp

ect g

uilty

; th

e sa

me

patte

rn d

id n

ot e

mer

ge fo

r tho

se w

ho in

itial

ly c

onsi

dere

d th

e su

spec

t inn

ocen

t.N

=10

7 po

lice

train

ees,

Swed

en•

Expl

anat

ory

Mea

sure

s: E

yew

itnes

s evi

denc

e co

nsist

ent o

r in

cons

isten

t with

initi

al b

elie

fs (r

ando

m a

ssig

nmen

t).H

uman

Nat

ure

• Pr

imar

y O

utco

me

Mea

sure

s: R

atin

gs o

f stre

ngth

of e

vide

nce,

pr

obab

ility

of g

uilt

(bot

h 1

to 9

Lik

ert s

cale

s), c

onvi

ctio

n de

ci-

sion

(dic

hoto

mou

s) b

efor

e an

d af

ter r

evie

w o

f witn

ess i

nfor

-m

atio

n; ra

tings

of r

elia

bilit

y of

the

spec

ific

witn

ess e

vide

nce

prov

ided

and

of t

he re

liabi

lity

of w

itnes

s evi

denc

e in

gen

eral

(1

to 9

Lik

ert s

cale

s) a

fter r

evie

w o

f witn

ess i

nfor

mat

ion.

Ras

sin

(201

0)•

Mat

eria

ls: H

omic

ide

case

a des

crip

tion

that

incl

uded

info

rma-

tion

abou

t a n

amed

fem

ale

susp

ect’s

mot

ive

and

info

rmat

ion

abou

t an

alte

rnat

ive

mal

e su

spec

t.

Resu

lts p

rovi

ded

som

e ev

iden

ce in

supp

ort o

f and

som

e ev

iden

ce

agai

nst t

he p

rese

nce

of c

onfir

mat

ion

bias

.

Stud

y 1:

N=

118

polic

e offi

cers

, dist

rict a

ttorn

eys,

and

judg

es, N

ethe

rland

s•

Expl

anat

ory

Mea

sure

s: C

ase

scen

ario

ver

sion

(ran

dom

ass

ign-

men

t).H

uman

Nat

ure

• Pr

imar

y O

utco

me

Mea

sure

s: R

atin

gs o

f pro

babi

lity

of g

uilt

(0 to

100

), an

d de

cisi

on to

con

vict

(dic

hoto

mou

s); r

atin

gs o

f de

gree

to w

hich

eac

h of

20

case

det

ails

supp

orte

d in

noce

nce

or g

uilt

of th

e na

med

susp

ect (

-5 to

5 L

iker

t sca

le),

com

bine

d in

to a

com

posi

te sc

ore.

Cas

e sc

enar

io v

ersi

on w

as a

ssoc

iate

d w

ith ra

tings

of p

roba

ble

guilt

(p

= 0

.03)

, but

not

with

dec

isio

n to

con

vict

(p =

0.8

6) o

r eva

luat

ion

of

case

det

ails

(p =

0.1

5)

Ras

sin

(201

8b)

• M

ater

ials

: Hom

icid

e ca

sea d

escr

iptio

n th

at in

clud

ed e

ither

in

form

atio

n ab

out a

nam

ed fe

mal

e su

spec

t’s m

otiv

e or

info

r-m

atio

n ab

out a

n al

tern

ativ

e m

ale

susp

ect.

Inte

rven

tion

was

pro

mis

ing

but n

o co

ntro

l gro

up in

corp

orat

ed in

to

study

.

Pri

or

No

Pri

or

Inte

rpre

tati

on

In

terp

reta

tion

Fat

her

-menti

oned

as e

xpla

nat

ion

9

4%

45%

(p

=0

.00

7)

Fat

he r

-mo

st l

ikel

y

expla

nat

ion 3

9%

10%

(p

=0

.06

)

Fat

her

-fu

rth

er

Inv

esti

gat

ion 5

6%

20%

(

p=

0.0

3)

[Mea

n ±

SD

]:

Rel

iabil

ity R

ati

ng

W

itn

ess

Ev

iden

ce:

for:

Incr

imin

atin

g E

xo

ner

atin

g

Spec

ific

Case

Gu

ilt

6.5

9 ±

1.6

7

4

.04

± 1

.76

(p

< 0

.00

4)

Innoce

nce

4.6

8 ±

2.2

6 4.4

3 ±

1.7

9 (

p =

0.2

7)

In G

ener

al

Gu

ilt

6.2

2 ±

0.9

3

4

.92

± 1

.38

(p

< 0

.00

4)

Inn

oce

nce

4.9

6 ±

1.5

0

4

.61

± 1

.32 (

p =

0.1

2)


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

Stud

y 2:

N=

45 p

olic

e offi

cers

, dist

rict a

ttorn

eys,

and

judg

es, N

ethe

rland

s•

Inte

rven

tion:

Pen

and

pap

er e

xerc

ise

ratin

g de

gree

to w

hich

ea

ch o

f 20

case

det

ails

indi

cate

d th

e na

med

susp

ect’s

gui

lt (1

0-po

int s

cale

; 0 =

exo

nera

ting,

10

= in

crim

inat

ing)

, pro

b-ab

ility

of g

uilt

(0 =

defi

nite

ly in

noce

nt to

100

= d

efini

tely

gu

ilty)

, and

con

vict

ion

deci

sion

(yes

/no)

. The

n to

ld to

imag

ine

that

the

unna

med

susp

ect h

ad c

omm

itted

the

crim

e an

d as

ked

to ra

te th

e de

gree

to w

hich

eac

h of

20

case

det

ails

indi

cate

d th

e al

tern

ativ

e su

spec

t’s g

uilt

(10-

poin

t sca

le; 0

= e

xone

ratin

g,

10 =

incr

imin

atin

g). A

fter t

his e

xerc

ise,

rate

d pr

obab

ility

of

nam

ed su

spec

t’s g

uilt

a se

cond

tim

e (0

= d

efini

tely

inno

cent

to

100

= d

efini

tely

gui

lty),

and

mad

e a

final

con

vict

ion

deci

sion

(y

es/n

o).

Sim

ilar r

atin

gs o

f the

ext

ent t

o w

hich

the

evid

ence

fit n

amed

susp

ect

hypo

thes

is a

nd a

ltern

ativ

e su

spec

t hyp

othe

sis [

Mea

n ±

SD

]:

Inte

rven

tion

• Pr

imar

y O

utco

me

Mea

sure

s: G

uilt

estim

ates

and

con

vict

ion

rate

s bef

ore

and

afte

r pen

and

pap

er a

nd im

agin

atio

n ex

erci

se.

Gui

lty e

stim

ate

decr

ease

d w

ith in

terv

entio

n:

Sale

t and

Ter

pstra

(201

4)•

Mat

eria

ls: I

n re

spon

se to

wro

ngfu

l con

vict

ion

in a

chi

ld se

x ab

use

and

mur

der c

ase

in th

e N

ethe

rland

s, a

natio

nal c

omm

is-

sion

reco

mm

ende

d us

e of

a c

ritic

al re

view

pro

toco

l (in

clud

ing

the

use

of c

ontra

rians

) for

com

plex

crim

inal

inve

stiga

tions

. Re

sear

cher

s ass

esse

d th

e im

plem

enta

tion

and

resu

lts o

f thi

s cr

itica

l rev

iew

pro

cedu

re th

roug

h a

revi

ew o

f rea

l cas

e fil

es

and

revi

ew d

ossi

ers f

rom

five

diff

eren

t pol

ice

forc

es a

nd in

ter-

view

s with

lead

inve

stiga

tors

and

con

traria

ns.

Crit

ical

revi

ews h

ad c

oncr

ete

effec

ts o

n cr

imin

al in

vesti

gatio

ns b

ut d

id

not r

adic

ally

cha

nge

the

dire

ctio

n of

any

cas

e.

N=

26 c

ase

files

and

dos

sier

s; in

terv

iew

s with

47

lead

ers o

f inv

estig

ativ

e te

ams a

nd “

cont

raria

ns,”

Net

herla

nds

• In

terv

entio

n: C

ritic

al re

view

pro

cedu

res i

ntro

duce

d in

to

polic

ewor

k.M

ost p

olic

e fo

rces

wer

e pr

actic

ing

criti

cal r

evie

ws i

n 20

11, b

ut v

aria

bil-

ity in

the

role

of c

ontra

rians

bet

wee

n fo

rces

. Som

e co

ntra

rians

use

d a

clos

enes

s stra

tegy

(act

ivel

y in

volv

ed in

the

inve

stiga

tion)

, whi

le o

ther

s us

ed a

dist

ance

stra

tegy

(rev

iew

ing

deci

sion

s afte

r the

y w

ere

mad

e).

Diff

eren

t con

traria

ns p

laye

d di

ffere

nt ro

les:

- ritu

alist

s (su

perfi

cial

revi

ew)

- pro

cedu

ralis

ts (c

once

ntra

te o

f rev

iew

ing

proc

edur

es)

- crim

inal

inve

stiga

tors

(con

cent

rate

on

revi

ewin

g su

bsta

ntiv

e el

emen

ts)

- coa

ch (c

once

ntra

te o

n im

prov

ing

qual

ity o

f lea

ders

hip

and

soci

al re

la-

tions

with

in th

e te

am)

- dev

il’s a

dvoc

ate

(cha

lleng

e w

ith a

ltern

ativ

e in

terp

reta

tions

and

hy

poth

eses

)In

terv

entio

n•

Prim

ary

Out

com

e M

easu

res:

Qua

litat

ive

com

paris

on o

f cas

e fil

es a

nd re

view

dos

sier

s and

info

rmat

ion

from

lead

inve

stiga

-to

rs a

nd c

ontra

rians

.

Nam

ed s

usp

ect

4.9

1 ±

0.7

2

Alt

ernat

ive

susp

ect

5.1

9 ±

1.1

6

[

p =

0.2

1]

Gu

ilty

est

imate

dec

reas

ed w

ith i

nte

rventi

on:

Bef

ore

45.6

7 ±

22.1

Aft

er

3

2.4

4 ±

20

.13

[

p <

0.0

01]

Dec

ision

to co

nvic

t dec

reas

ed w

ith in

terv

entio

n:Be

fore

22%

of p

artic

ipan

tsA

fter

7%

of p

artic

ipan

ts

[p <

0.0

4]


1 3

Refe

renc

e, P

artic

ipan

ts, R

esea

rch

Focu

sM

etho

ds a

nd M

easu

res

Resu

lts

Wal

lace

(201

5)•

Mat

eria

ls: C

ompu

ter-a

dmin

ister

ed se

xual

ass

ault

case

vig

nette

(w

ith e

ither

a c

hild

or a

dult

vict

im),

incl

udin

g 10

item

s of

evid

ence

(pre

sent

ed e

ither

sim

ulta

neou

sly, s

eque

ntia

lly, o

r in

reve

rse-

sequ

entia

l ord

er).

Rat

ed c

onfid

ence

in g

uilt

or in

no-

cenc

e af

ter e

very

pie

ce o

f evi

denc

e an

d pr

ovid

ed a

n ov

eral

l, fin

al d

ecis

ion

abou

t gui

lt or

inno

cenc

e.

Resu

lts d

id n

ot su

ppor

t the

hyp

othe

sis t

hat e

xtre

me

emot

ion

did

not

impa

ct g

uilt

judg

emen

ts (o

r tha

t vic

tim a

ge is

not

an

effec

tive

man

ipu-

latio

n of

ext

rem

e em

otio

n) a

s the

age

of t

he se

xual

ass

ault

vict

im d

id

not i

nflue

nce

guilt

judg

men

ts.

N=

166

polic

e offi

cers

(bas

ic tr

aini

ng re

crui

ts, p

atro

l offi

cers

, and

crim

inal

inve

stiga

tors

), U

nite

d St

ates

• Ex

plan

ator

y M

easu

res:

Pre

sum

ed e

mot

iona

l im

pact

of c

ase

scen

ario

ver

sion

(ran

dom

ass

ignm

ent),

pro

fess

iona

l exp

eri-

ence

(rec

ruit,

pat

rol,

inve

stiga

tor)

, evi

denc

e pr

esen

tatio

n or

der –

exc

ulpa

tory

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esen

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early

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ate

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t).

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as. W

hen

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r to

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ory

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ly.

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divi

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erist

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ary

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com

e M

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1 3

Acknowledgments Thank you to Dr. Karen Amendola (Police Foun-dation), Ms. Prahelika Gadtaula (Innocence Project), and Dr. Kim Rossmo (Texas State University) for their thoughtful reviews of ear-lier drafts.

Compliance with Ethical Standards

Conflict of Interest The authors declare that they have no conflict of interest.

Ethical Statement This article does not contain any studies with human participants or animals performed by either of the authors.

Open Access This article is licensed under a Creative Commons Attri-bution 4.0 International License, which permits use, sharing, adapta-tion, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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