Science and Pseudoscience in Law Enforcement

• Date: 01 October 2008
• DOI: 10.1177/0093854808321526
• Published date: 01 October 2008
• Subject Matter: Articles

SCIENCE AND PSEUDOSCIENCE IN LAW

ENFORCEMENT

A User-Friendly Primer

SCOTT O. LILIENFELD

KRISTIN LANDFIELD

Emory University, Atlanta, Georgia

Pseudoscience and questionable science are largely neglected problems in police and other law enforcement work. In this

primer, the authors delineate the key differences between science and pseudoscience, presenting 10 probabilistic indicators

or warning signs, such as lack of falsifiability, absence of safeguards against confirmation bias, and lack of self-correction,

that can help consumers of the police literature to distinguish scientific from pseudoscientific claims. Each of these warning

signs is illustrated with an example from law enforcement. By attending to the differences between scientific and

pseudoscientific assertions, police officers and other law enforcement officials can minimize their risk of errors and make

better real-world decisions.

Keywords: pseudoscience; police; law enforcement; falsifiability; peer review; confirmation bias

Throughout their careers, police and other law enforcement officials face an enormous

array of challenges involving threats to life and liberty: questions of innocence versus

guilt, split-second decisions regarding how to respond in a crisis, attempts to locate miss-

ing persons and solve serious crimes, lie detection, and the reconstruction of past criminal

events, to name but a few. The accuracy of these techniques has the potential to determine

crucial decisions, even those involving life or death. As in most professions, individuals in

law enforcement must evaluate techniques with a critical eye before using them. Like all

disciplines that interpret data to make real-world decisions, police work can easily fall prey

to the seductive charms of pseudoscience.

Given these formidable challenges, it is hardly surprising that law enforcement officials

have turned to scientific psychology for assistance in developing valid forensic techniques

and evaluating the validity of scores of others. In the 1870s, Sir Francis Galton, cousin of

Charles Darwin, experimented with a word association test (in which a test examiner says

a word, like “money,” and awaits a response from the respondent) as a tool for lie detection

(Matte, 2002). Similarly, in the early 1900s, Hugo Munsterberg (1908) performed classic

demonstrations that underscored the fallibility of eyewitness testimony. Since then, psycho-

logical researchers have spearheaded the development of scientifically grounded proce-

dures to enhance the accuracy of forensic techniques.

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CRIMINAL JUSTICE AND BEHAVIOR, Vol. 35 No. 10,October 2008 1215-1230

DOI: 10.1177/0093854808321526

© 2008 International Association for Correctional and Forensic Psychology

AUTHORS’ NOTE: The authors thank Dr. Carol Tavris, Dr. Brent Snook, and an anonymous reviewer for

their extremely helpful comments on an earlier draft of this article. All correspondence concerning this article

should be addressed to Scott O. Lilienfeld, PhD, Department of Psychology, Room 206, Emory University, 532

Kilgo Circle, Atlanta, Georgia 30322; e-mail: slilien@emory.edu.

Nevertheless, like many professions, including psychology itself, law enforcement has

long struggled with the thorny problem of distinguishing scientifically supported from sci-

entifically unsupported practices. Because much of police work has developed in isolation

from psychological science, its practices are a jumbled mix of legitimate and illegitimate

claims (see Brewer & Wilson, 1995, for an introduction). This special issue of Criminal

Justice and Behavior focuses on the largely neglected problem of pseudoscience in police

work and highlights several prominent examples of law enforcement techniques that fall

either on or outside the murky fringes of pseudoscience.

PSEUDOSCIENCE DEFINED

Before discussing specific law enforcement techniques that fall under the broad umbrella

of pseudoscience, we must define pseudoscience and how it differs from bona fide science.

Traditionally, pseudosciences are disciplines that possess the superficial appearance of

science but lack its substance (Lilienfeld, 1999; Ruscio, 2006). More informally, pseudo-

sciences are imposters of science: They do not play by the rules of science even though they

mimic some of its outward features. As a consequence, they can easily mislead untrained

observers into concluding that they possess scientific merit. A cousin of pseudoscience is

“junk science,” sometimes described as the intrusion of scientifically unwarranted claims

into the courtroom (Huber, 1991; Park, 2001).

Pseudosciences have a hoary and checkered history in psychology (Leahey & Leahey,

1983). Such disciplines as phrenology, physiognomy, parapsychology (the study of

extrasensory perception and psychokinesis), astrology, and subliminal persuasion for

advertising purposes, among many others (see Hines, 2003), have traditionally displayed

many of the telltale signs of pseudoscience. Nevertheless, pseudosciences are defined not

by their object of study per se but by their approach to evidence, especially negative evi-

dence (Lilienfeld, Lynn, & Lohr, 2003). In contrast to most developed sciences, which

eventually—if often reluctantly—assimilate negative evidence into their corpus of belief,

most pseudosciences remain largely insulated from contradictory data. It is in principle

possible to approach parapsychology, for example, from a scientific perspective, assuming

that investigators are willing to admit well-replicated negative data into their web of belief

and revise their hypotheses accordingly. Nevertheless, many parapsychologists (e.g.,

Radin, 1997) have not done so and insist that the evidence for extrasensory perception and

related phenomena is promising or even conclusive despite approximately 150 years of

repeated failures to replicate initial positive findings (Gilovich, 1991; Hyman, 1989).

Philosopher of science Mario Bunge (1983) proposed the categories of “research fields”

and “belief fields” to demarcate sciences from pseudosciences, arguing that scientific prac-

tices are distinguished by research support as opposed to intuition or faith. For instance,

subjective experience and intuition alone are insufficient for police officers to believe that

their interrogation procedures produce accurate confessions; these procedures must be

validated by scientific evidence.

Science and pseudoscience are not always easy to distinguish, because they probably fall

at opposite ends of a continuum, differing in degree rather than in kind (Lilienfeld, 1999;

Lilienfeld et al., 2003). Like many mental concepts, pseudoscience is probably an open

concept (see Meehl, 1986) or “Roschian concept” (see Rosch, 1973; Rosch & Mervis,

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