Pathological Lying: Theoretical and Empirical Support for a Diagnostic Entity

Abstract

Objective:
Pathological lying, originally called “pseudologia phantastica,” has an established history within clinical practice and literature, although it has not been recognized as a psychological disorder within major nosological systems. With the movement in psychological sciences toward theory-driven, empirically supported diagnoses, the current study sought to empirically test whether pathological lying aligned with nosological definitions and could be defined as a diagnostic entity.

Methods:
A total of 807 people were recruited (January to October of 2019) from various mental health forums, social media, and a university. Of those recruited, 623 completed the study. Participants responded to a lie frequency prompt, questionnaires about lying behavior, the Lying in Everyday Situations Scale, the Distress Questionnaire-5, and demographic questions.

Results:
Of the participants, 13% indicated that they self-identified or that others had identified them as pathological liars (telling numerous lies each day for longer than 6 months). People who identified as pathological liars reported greater distress, impaired functioning, and more danger than people not considered pathological liars. Pathological lying seemed to be compulsive, with lies growing from an initial lie, and done for no apparent reason.

Conclusions:
The evidence supports establishment of pathological lying as a distinct diagnostic entity. A definition of pathological lying, etiological considerations, and recommendations for future research and practice are presented.

Full text

Pathological Lying: Theoretical and Empirical Support
for a Diagnostic Entity
Drew A. Curtis, Ph.D., and Christian L. Hart, Ph.D.
Objective: Pathological lying, originally called “pseudologia
phantastica,”has an established history within clinical prac-
tice and literature, although it has not been recognized as a
psychological disorder withinmajornosologicalsystems.
With the movement in psychological sciences toward
theory-driven, empirically supported diagnoses, the current
study sought to empirically test whether pathological lying
aligned with nosological definitions and could be defined as a
diagnostic entity.
Methods: A total of 807 people were recruited (January
to October of 2019) from various mental health forums, social
media, and a university. Of those recruited, 623 completed the
study. Participants responded to a lie frequency prompt, ques-
tionnaires about lying behavior, the Lying in Everyday Situations
Scale, the Distress Questionnaire-5, and demographic questions.
Results: Of the participants, 13% indicated that they self-
identified or that others had identified them as pathological
liars (telling numerous lies each day for longer than 6 months).
People who identified as pathological liars reported greater
distress, impaired functioning, and more danger than people
not considered pathological liars. Pathological lying seemed
to be compulsive, with lies growing from an initial lie, and
done for no apparent reason.
Conclusions: The evidence supports establishment of path-
ological lying as a distinct diagnostic entity. A definition
of pathological lying, etiological considerations, and re-
commendations for future research and practice are
presented.
PRCP in Advance (doi: 10.1176/appi.prcp.20190046)
The frequency with which people lie varies (1, 2). Consid-
erable research has focused on the normative aspects of
lying (1, 3–7). Deception has been defined by Vrij (3) as “a
successful or unsuccessful deliberate attempt, without
forewarning, to create in another a belief which the com-
municator considers to be untrue.”Some studies report that
people tell an average of two lies per day (4, 8, 9). Two recent
studies, however, discovered that a majority of people re-
ported telling no lies within the past 24 hours, whereas a
small subset reported telling numerous lies (1, 2). Although
extensive research has explored the normative aspects of
lying among the general population, and within psycho-
therapy (10–13), the pathological dimensions of deception
have been neglected.
Pathological lying (PL) has been referenced in popular
culture, although some have suggested that psychiatrists
and psychologists know little about the phenomenon (14). PL,
originally termed “pseudologia phantastica,”was first re-
corded in 1891 by psychiatrist Anton Delbrück in discussions
of several cases of people who told so many outrageous lies
that the behavior was considered pathological (15). Today,
there is little consensus for a definition of PL, but many
continue to use a definition proposed by Healy and Healy
more than a century ago (15). They defined PL as “falsification
entirely disproportionate to any discernible end in view, may
be extensive and very complicated, manifesting over a period
of years or even a lifetime, in the absence of definite insanity,
feeblemindedness or epilepsy.”
The DSM-5 defines a mental disorder as a syndrome that
causes significant distress and impairs functioning (16). Similarly,
the ICD-10 defines a disorder as a “set of symptoms or behaviour
associated in most cases with distress and with interference
with personal functions”(17). From these definitions, models of
HIGHLIGHTS
•Pathological lying exists in a small percentage of people,
for whom it causes significant distress, impaired func-
tioning, and danger.
•Pathological lying, distinct from normative lying and pro-
lific lying, has a prevalence of 8%–13%.
•Evidence supports establishing pathological as a diagnos-
tic entity.
prcp in Advance prcp.psychiatryonline.org 1
ARTICLES

abnormality have been suggested, such as the four Fs:
frequency, function, feeling pain, and fatal (18). In com-
parison with contemporary models of psychopathology, the
definition of PL put forth more than a century ago does not
fully capture aspects of pathology (15). Therefore, to merge
the key elements of the previous definition with psychopa-
thology criteria from classification systems, we suggest that
PL should be defined as a persistent, pervasive, and often
compulsive pattern of excessive lying behavior that leads to
clinically significant impairment of functioning in social,
occupational, or other areas; causes marked distress; poses
a risk to the self or others; and occurs for longer than
6months.
PL has not been classified within the DSM-5 or the ICD-10
(16, 17). The DSM-5 mentions that deception is a symptom of
antisocial personality disorder and is used for external in-
centive (malingering) and to assume a sick role (factitious
disorder) (16). PL is one of 20 items used in the Hare Psy-
chopathy Checklist-Revised (PCL) (19). However, this item
does not serve to provide a diagnosis but to assess lying
behavior related to psychopathy.
Research investigating PL is scant. One study of 1,000
young offenders found excessive lying among 15% of males
and 26% of females (15). A recent imaging study found that
12 participants who endorsed the PL item from the PCL
showed an increase in prefrontal white matter and re-
duction in gray matter and white matter ratios compared
with normal control participants and antisocial control
participants (20). Research on PL has mostly involved case
studies. Delbrück discussed five case studies, and Healy
and Healy identified 12 case studies (15). Across the subse-
quent 100 years, other PL case studies have been published
(21–23). A comprehensive analysis of 72 case studies (24)
showed that PL was equally represented among men and
women of average to above average intelligence, typically
beginning in adolescence, with some people committing
crimes. Although evidenced in case studies, the distinc-
tiveness of PL has been debated (25–27), with some arguing
that PL is a unique disorder (14, 15).
The purpose of the current study was to explore a theo-
retical model of PL as a distinct psychopathology that meets
major nosological definitions, namely a disorder bearing the
features of frequency, function, feeling pain, and fatality. On
the basis of this hypothesis, we made six predictions: Our first
prediction was about prevalence, frequency of behavior, and
duration of the condition. We predicted that patients with
PL would represent a smaller percentage of the population
reporting excessive lying, would report PL as lasting for a
longer time than would the general population, and would
report onset of the condition as occurring during adoles-
cence. Our second prediction was that patients with PL would
report impaired functioning in several areas. Our third
prediction was that patients with PL would report more
distress from their lying than would the general population.
Our fourth prediction was about fatality; we predicted that
patients with PL would be more likely to report that their lies
put themselves or others in danger. Our fifth prediction was
that patients with PL would indicate that their lying was not
entirely under their control and that it provided relief from
anxiety. Our sixth prediction was that patients with PL would
report telling lies for no specific reason and that their lies
would tend to grow from an initial lie more so than those of
people without PL.
METHODS
Participants
We recruited 807 people via Facebook, Reddit/samplesize,
Psych Forums, and a university in the southwestern United
States to participate in a study on lying behavior. A total of
635 participants completed information beyond the inclu-
sion criteria. Three participants were removed because of
reporting an unlikely number of lies told, and nine partici-
pants were excluded because they indicated they had lied in
response to some of the survey questions. Thus, 623 partic-
ipants were retained for the analyses.
Participantsrangedinagefrom18to60years(mean6
SD=21.9767.57) with more female (N=374, 68%) partici-
pants than male. The majority of participants were Cau-
casian and/or European American (N=325, 59%), followed
by Hispanic and/or Latinx (N=135, 25%); multiracial (N=41,
8%); African American and/or Black (N=20, 4%); Asian,
Asian American, and/or Pacific Islander (N=19, 4%); and
Native American and/or Alaskan Native (N=8, 2%). The par-
ticipants ranged in education, from having no high school
diploma (N=6, 1%), a GED (N=4, 1%), a high school diploma
(N=210, 38%), a col lege degree (N=309, 56%), a master’s degree
(N=21, 4%), and a doctoral degree (N=2, ,1%). A majority of
participants indicated that their annual income was under
$25,000 (N=456, 85%), with fewer reporting annual incomes
of$25,000to$49,000(N=44,8%),$50,000to$75,000(N=18,
3%), and $75,000 or more (N=22, 4%). Although the complete
sample of 623 participantsdrew from a range of ages, ethnicity,
education, and income, participants were slightly younger,
more Hispanic, more educated, and had lower incomes than
the general population.
Materials
Participants were asked about whether they considered
themselves to be pathological liars and whether others
considered them to be pathological liars. Additionally, par-
ticipants were given a lie frequency assessment (1, 2) (Figure 1)
and other questionnaires. The Survey of Pathological Lying
behaviors (SPL) is a nine-item questionnaire about function-
ing, feeling pain, and fatal risks of lying behavior that uses a
Likert-type ratingscale (1=strongly disagree; 7=strongly agree)
(see the online supplement accompanying this article). In-
ternal consistency for the SPL was acceptable (Cronbach’s
a=0.82). The Survey of Lying Behaviors is a seven-item survey,
reporting on the frequency, functioning, pain, and risks the
respondent perceives as related to lying behavior, and has a
Cronbach’saof 0.80. The Survey of Others’Pathological
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THEORETICAL AND EMPIRICAL SUPPORT FOR PATHOLOGICAL LYING AS A DIAGNOSTIC ENTITY

Lying is an 11-item questionnaire, reporting on the frequency,
functioning, pain, and risks respondents perceive as related to
the lyingbehaviors of others (Cronbach’sa=0.83).The Lying in
Everyday Situations (LiES) Scale (28) is a 14-item scale de-
signed to assess the propensity to lie. The LiES scale has
demonstrated high internal consistency, test-retest reliability,
and concurrent validity and displayed high internal consis-
tency reliability in the current study (Cronbach’sa=0.88). The
Distress Questionnaire-5 (DQ5) is a five-item screen, with
suggested sensitivity and specificity cutoff points, used to
measure general psychological distress among individuals
with various psychological disorders (29) (Cronbach’sa=0.83).
A demographic questionnaire also was provided.
Procedure
The institutional review board of Angelo State University
approved the study. Following written consent, we presented
the participants with a prompt and lie frequency assessment
(1) (Figure 1). We then asked three questions which we used
to identify assignment to the PL or non-PL condition. Par-
ticipants in the PL condition completed the SPL, LiES, DQ5,
and the demographic questionnaire. Participants in the
non-PL condition completed the Survey of Lying Behaviors,
LiES, DQ5, and the demographic questionnaire. Additionally,
participants in the non-PL condition completed the Survey of
Others’Pathological Lying if they indicated that they knew
someone whom they believed was a pathological liar. All
participants were debriefed after participating in the study.
RESULTS
Identification of Pathological Lying
We assigned participants to the pathological lying condition if
they considered themselves pathological liars or if others
considered them pathological liars. Statistics for normally
distributed data are likely to be unreliable for handling lie
distributions, which have consistently been shown to be
positively skewed (1, 2). Thus, we conducted a negative bi-
nomial regression to examine the fit of the frequency of lies
with self-identified PL, because it is a robust method for
handling overdispersed count data (30). The likelihood ratio
chi-square test indicated that the model was a significant
improvement in fit over a null model (p,0.001). Thus, the
self-identification of a PL and non-PL model was found to be a
better fit and was retained.
Of the 623 participants, 83 (13%) indicated that they or
others considered themselves pathological liars (35 indicated
only self, 27 indicated only others, 12 indicated both, and nine
affirmed self or others). A chi-square analysis revealed a
statistically significant difference between people in the PL
and non-PL conditions (x
2
=335.23, N=623, df=1, p,0.001). Of
the 589 participants who responded to the question that
asked about having been formally diagnosed by a mental
health professional with a psychological disorder, 49 (8%)
indicated they were pathological liars. Thus, our prediction
was confirmed that PL would occur within a relatively small
percentage of the sample (8%–13%).
FIGURE 1. Screen shot of lie frequency assessment
a
Talked to them
face-to-face
Talked to them in
writing or by phone or
over the Internet
4) Family members
5) Friends or other people you know socially
6) People you work with or know as business contacts
7) People you do not know but might see occasionally
(such as a store clerk)
8) Total strangers
Think about where you were and what you were doing during the past 24 hours, from this time yesterday until right
now. Listed below are the kinds of people you might have lied to and how you might have talked to them, either
face-to-face or some other way such as in writing or by phone or over the Internet. In each of the boxes below,
please write in the number of times you have lied in this t ype of situation. If you have not told any lies of a particular
type, write in “0.”
In the past 24 hours, how many times have you lied?
Please enter a number for each person
Continue ONLY when fi nished. You will be unable to return or change your answers.
Continue »
a
Source: Serota et al. (1).
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CURTIS AND HART

We conducted a chi-square test of independence to com-
pare the frequency of formal psychiatric diagnoses among the
PL group and those in the non-PL group and found no sig-
nificant association (x
2
=4.42, N=553, df=2, p=0.11). Thus,
participants in the PL group were no more likely to have a
psychiatric diagnosis than those in the non-PL group.
We conducted an independent samples t-test to examine
whether there were differences in age between the PL group
and non-PL group and found no statistically significant dif-
ferences (t=–0.62, df=519, p=0.54). Chi-square tests of in-
dependence found no significant association for sex (x
2
=0.92,
N=551, df=2, p=0.63), education (x
2
=0.89, N=552, df=5,
p=0.97), income (x
2
=2.77, N=540, df=3, p=0.43), or ethnicity
(x
2
=12.05, N=548, df=6, p=0.06). To examine whether edu-
cation (inclusion of a college sample) resulted in the differ-
ences, we created an educationvariabletodifferentiate
between those with a college degree or higher and those with
a high school education or less. In addition, we used a mul-
tivariate analysis of variance (MANOVA) to compare educa-
tion across lying frequency, distress, functioning, and danger
and found no statistical significance for the PL group (F=1.97,
df=7 and 58, p=0.07) or the non-PL group (F=0.49, df=7 and
424, p=0.84).
Frequency (Prediction 1)
To further test prediction 1, we used a chi-square test to
examine duration of engagement in PL, which demonstrated
statistical significance (x
2
=59.18, N=78, df=24 p,0.001). A
majority of participants in the PL group reported engaging in
PL for 6 months or longer (N=68, 87%), with more than half
(N=42, 54%) indicating they had engaged in frequent lying for
more than 5 years (Table 1).
We conducted an independent samples t-test to examine
the difference in the number of lies told by participants in the
PL group compared with the non-PL group and found a
statistically significant difference (t=7.52, df=588, p,0.001).
As predicted, participants in the PL group indicated telling
more lies within a 24-hour period (mean=9.99611.17, me-
dian=7, mode=1, N=82, maximum=66 lies, 95% confidence
interval [CI]=7.5–12.44, skewness=2.27 [SE=0.27], and kur-
tosis=7.20, [SE=0.53]) than participants in the non-PL group
(mean=3.0966.86, median=1, mode=0, N=499, maximum=80
lies, 95% CI=2.49–3.70,skewness=6.79[SE=0.11],kurto-
sis=58.43 [SE=0.22]). We conducted a one-sample t-test on
the PL condition, and a test value of five revealed a statistically
significant difference (t=4.04, df=81, p,0.001). Confirming
our hypothesis, a majority of participants in the PL group
(N=49, 60%) reported telling five or more lies within the past
24 hours. Furthermore, the PL group told more lies in per-
son (mean=6.3567.75) than over the phone or in writing
(mean=3.8865.82, t=2.85, df=76, p=0.006). We conducted a
MANOVA to determine to whom the participants in the PL
group reported telling lies and found statistical significance
(F=13.71, df=5 and 76, p,0.001). Participants in the PL group
reported lying more to friends and social acquaintances than
to other people (Table 2).
We used an independent samples t-test to compare scores
on the LiES between the PL and non-PL groups and found a
statistically significant difference (t=7.09, df=78, p,0.001).
Those in the PL group reported a greater propensity for
telling lies in their everyday lives (mean=50.80618.00) than
those in the non-PL group (mean=34.88612.59).
A frequencyanalysis revealedthat a majority of participants
in the PL group indicated onset of PL during adolescence
(10–20 years) (N=48, 62%). A chi-square analysis showed a
statistically significant difference between developmental
periods (x
2
=35.62, N=78, df=2, p,0.001), with most partic-
ipants reporting that the earliest age they were considered a
pathological liar was in adolescence (N=48).
Impaired Functioning (Prediction 2)
To assess impaired functioning, we conducted a MANOVA
with areas of functioning as the dependent variable and the
lying condition as the between groups variable. A statistical
significance was shown (F=24.09, df=4 and 549, p,0.001).
Univariate tests indicated statistical significance between the
PL and non-PL groups’impairment in functioning in occu-
pation (F=15.32, df=1 and 552, p,0.001), social relationships
(F=83.88, df=1 and 552, p,0.001), finances (F=27.42, df=1
and 552, p,0.001), and legal contexts (F=29.04, df=1 and
552, p,0.001). Within the PL group, a repeated measures
MANOVA showed statistical significance in areas of func-
tioning (F=16.16, df=3 and 72, p,0.001). Pairwise compari-
sons found the greatest impairment in social relationships
(p,0.001) (Table 3).
Feeling Pain (Prediction 3)
Participants in the PL group reported greater distress from
their lying (mean=3.0462.02) compared with those in the
non-PL group (mean=2.2161.65, t=3.44, df=94, p=0.00).
Participants in the PL group reported greater general psy-
chological distress (mean=15.7665.11) than the non-PL group
(mean=14.5064.63, t=2.15, df=539, p=0.03). By using DQ5
suggested cutoff points for sensitivity ($11) and specificity
($14), 9% (N=59) and 8% (N=50) of the overall sample were
identified as those in the PL group who experience psy-
chological distress, respectively.
Fatal Danger (Prediction 4)
We used an independent samples t-test to compare the PL
and non-PL groups on scores of whether their lying put them
or others in danger. A statistically significant difference was
TABLE 1. Duration of engagement in pathological lying among
participants considered pathological liars (N=78)
a
Duration N %
3 months 10 13
6 months 8 10
1 year 4 5
1–5 years 14 18
.5 years 42 54
a
Data missing for five of the 83 participants considered pathological liars.
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THEORETICAL AND EMPIRICAL SUPPORT FOR PATHOLOGICAL LYING AS A DIAGNOSTIC ENTITY

found (t=5.53, df=82, p,0.001). Participants in the PL group
reported that their lying had placed themselves or others in
danger (mean=2.7662.16) more so than participants in the
non-PL group (mean=1.3861.00).
Compulsivity (Prediction 5)
To assess compulsivity, we conducted a MANOVA on two
items (feeling out of control and for relief from anxiety) and
found statistical significance (F=90.47, df=2 and 563,
p,0.001). Participants in the PL group indicated that their
lying was out of their control more (mean=3.2962.25) than
did individuals in the non-PL group (mean=1.3860.93,
p,0.001).Additionally,thePLgroupfeltlessanxiousafter
lying (mean=3.5162.23) compared with the non-PL group
(mean=1.9561.55, p,0.001).
Motivation and Growth of Lies (Prediction 6)
We conducted an independent samples t-test to examine
whether the participants in the PL group were more likely
than those of the other group to report that they told lies for
no reason. A significant difference was found (t=6.13, df=92,
p,0.001). Participants in the PL group told lies for no rea-
son (mean= 3.7362.30) more than participants in the non-PL
group (mean=2.0961.64). Additionally, we used an inde-
pendent samples t-test to examine group differences in the
belief that their lies grew. The results showed a statistically
significant difference (t=6.46, df=91, p,0.001), with those in
the PL group indicating their lies grew from an initial lie
(mean=3.8162.22) more so than did those in the non-PL
group (mean=2.1561.15).
Pathological Liars Versus Prolific Liars
Prolific liars were identified from the non-PL sample in a
manner similar to Serota and Levine’s (2) by using an index of
dispersion (D) to decide whether the data fit a distribution.
We used a negative binomial regression because of over-
dispersed data (30). To achieve a dispersion closest to 1, we
divided the sample into two groups: those who told zero to
two lies (mean=0.6660.77, D=0.89) and those who told three
or more lies (prolific liars) (mean=7.51610.09, p,0.001).
Thus, prolific liars were coded into a new condition variable.
An independent samples t-test found no significant dif-
ference in number of lies told between the PL group and the
prolific lying group (p=0.09). However, a significant differ-
ence was seen on the LiES (t=6.12, df=224, p,0.001). Par-
ticipants in the PL group reported greater propensity for
telling lies (mean=50.80618.00) compared with participants
in the prolific lying group (mean=38.32612.03).
We used a MANOVA to analyze areas of functioning
between participants assessed as pathological liars and those
assessed as prolific liars and found a statistical significance
(F=8.86, df=4 and 230, p,0.001). Univariate tests indicated
statistical significance for lower functioning among PL par-
ticipants in occupation (F=4.40, df=1 and 233, p=0.037), social
relationships (F=28.44, df=1 and 233, p,0.001), finances (F=7.43,
df=1 and 233, p=0.007), and legal contexts (F=12.51, df=1 and 233,
p,0.001). An independent samples t-test found a significant
difference between the PL group (mean=3.0462.02) and those
classified as prolificliars(mean=2.4961.63) with regard to lying
causing distress (t=2.08, df=127, p=0.039). Lying was also reported
to be more dangerous by the PL group (mean=2.7662.16) than by
the prolific liar group (mean=1.5861.19,t=4.49, df=100, p,0.001).
Perceptions of Pathological Liars
Of the participants who did not indicate being a pathological
liar, 162 indicated that they knew someone they considered a
pathological liar. Participants estimated that these individ-
uals had told an average of approximately 10 lies within
the last 24 hours, with five lies as the most frequent response
(mean=9.96615.47 lies told, median=5, mode=5, N=127,
maximum=130 lies, 95% CI=7.24–12.68, skewness=5.53 [SE=0.22],
kurtosis=37.13 [SE=0.43]). A majority of participants reported
either that the person did not have a formal diagnosis (N=67,
42%) or that they did not know whether the person had
a formal diagnosis (N=73,46%. Most of these participants
TABLE 3. Pairwise comparisons of impairment in areas of
functioning among participants considered pathological liars
(N=75)
a
Function M SD p
Occupation 2.01 1.46
Social relationships
b
3.52 2.09 ,0.001
Finances
c
2.32 1.83 0.02
Legal contexts 1.88 1.57
a
Data missing for five of the 83 participants considered pathological liars.
b
p,0.001 for all other areas of functioning.
c
p,0.05 compared with legal contexts.
TABLE 2. Lies told by participants considered pathological liars
(N=75), by relationship
a
Relationship M SD
Family member (face-to-face) 1.40 2.59
Family member (writing or
phone or internet)
1.11 2.48
Friends or other people you
know socially (face-to-face)
2.07 2.71
Friends or other people you
know socially (writing,
phone, or Internet)
1.53 2.32
People you work with or know
as business contacts (face-
to-face)
1.37 3.12
People you work with or know
as business contacts
(writing, phone, or Internet)
0.59 1.53
People you do not know but
might see occasionally
(face-to-face)
0.83 1.92
People you do not know but
might see occasionally
(writing, phone, or Internet)
0.28 0.91
Total strangers (face-to-face) 0.76 2.48
Total strangers (writing,
phone, or Internet)
0.37 1.08
a
Data missing for eight of the 83 participants considered pathological liars.
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CURTIS AND HART

reported that the earliest stage of development when the
person was perceived as a pathological liar was adolescence
(N=83, 52%) or that they did not know (N=42, 26%). A ma-
jority of these participants also reported that the person they
knew had been telling numerous lies for .6 months (N=121,
76%) or that they did not know (N=35, 22%). A MANOVA
revealed a statistically significant difference in areas of func-
tioning (F=590.35, df=4 and 154, p,0.001). Participants in-
dicated that the person’s lying had resulted in impaired
functioning more in social relationships (mean=5.9362.14)
than in occupation (mean=3.9362.14), finances (mean=3.846
2.24), or legal contexts (mean=3.2762.15). An independent
samples t-test was used to compare distress between the PL
group (mean=3.0462.01) and participants in the non-PLgroup
who reported knowing someone they considered a patho-
logicalliar (mean=4.2462.00), findinga statisticallysignificant
difference (t=–4.32, df=223, p,0.001). An independent sam-
ples t-test also showed a statistically significant difference in
danger between those in the PL group (mean=2.7662.16) and
those the participants’considered pathological liars (mean=
5.6461.49, t=–10.59, df=115, p,0.001).
DISCUSSION
The historical discussion of PL has been robust. Documented
case studies have supplied ample evidence of patients with PL
behavior in clinical practice. Yet, nosological systems have
not classified PL as a distinct entity. Attending to the credence
of theory-driven, empirical approaches to psychopathology
(31–33), the current study provides evidence for PL as a
disorder and aligns with the requirements set forth by the
American Psychiatric Association for the addition of a new
diagnostic category (34). By applying definitions and criteria
from psychopathology models, a distinguishable group of
people emerges who lie excessively for extended periods and
experience impaired functioning, significant distress, and
increased danger.
Our findings showed that the participants classified as
pathological liars reported telling about 10 lies per day on
average, and most reported telling one lie per day. This av-
erage is greater than the number of lies told by a normative
sample, in the current study, and in previous research (1–4, 7,
8). Additionally, those in the PL group indicated a greater
propensity to tell lies, and the excessive lying had persisted
for longer than 6 months, a duration similar to that of other
DSM-5 disorders (16). Estimates of PL in the current sample
ranged from 8%–13%. This range represented those who
reported no psychological disorder (8%), those who currently
met the DQ5 specificity criteria for distress (8%), and those
who self-identified (13%) as pathological liars.
Our results indicate a distinction between prolific and
pathological liars, with the latter endorsing greater distress,
impaired functioning, risk of harm, and propensity to lie. The
area of greatest impairment in functioning for those in the PL
group was in social relationships. This finding was not sur-
prising, because deception often damages trust, especially
when used to conceal a transgression (35, 36). Our results
provide a strong argument that a definition of PL should hinge
not solely on the frequency of the lying behavior, but on the
indices of psychopathology.
Participants in the PL group reported experiencing more
distress from telling lies. Classic research indicates that lying
can reduce distress when behavior is discrepant from beliefs,
acting as a distress-relieving mechanism (37, 38). However,
lying can cause distress because it requires a justification for
its use (4, 39). For pathological liars, the distress may result
from telling lies for no apparent reason, with lies growing
from an initial lie, and from concern about discovered de-
ceptions and relational conflict. Additionally, the PL condi-
tion indicated greater psychological distress, suggestive of a
distinct mental disorder.
The fatal criterion was met because PL was more likely to
put oneself or others in danger. An example of lying that may
pose a threat to one’s safety is if one conceals suicidal ideation
during psychotherapy (40).
In addition to the pathological distinctions, we found that
those in the PL group indicated that telling lies reduced their
anxiety and that their lying was out of their control. Fur-
thermore, PL behavior involves telling lies without a specific
reason, with lies growing from an initial lie. Thus, PL contains
elements of compulsiveness. The subsequent growth of lies,
however, tends to cause more distress.
Limitations
The current study had some limitations. Participants were
recruited from forums that may attract people interested in
psychological disorders, which may have increased the PL
sample, resulting in a slightly larger prevalence than what
may be expected in the general population. However, this
method of recruitment was necessary to reach the target
sample, because PL is not an official classification within the
DSM-5. Although PL is not a formal diagnostic entity, it has
been widely discussed by mental health professionals and
people who maintain difficulty with lying behaviors. Addi-
tionally, our sample included an age range of 18–60, with an
average age of about 22 and many having advanced education.
Although we found no statistical difference in a comparison of
education levels, use of this sample may have underestimated
some of the negative life consequences of PL compared with
individuals who are older or less educated. Another potential
concern was the self-report. We used this method because PL
has not been established as a diagnostic entity. Additionally,
self-reporters are most likely to seek out treatment. When
asking people to report on their lying behaviors, there may be
concern that the self-reports are lies. However, evidence
suggests that self-reports of lying behavior are valid and re-
liable (1, 2, 41). Halevy and colleagues found that self-reported
frequency of lying behaviors was not significantly correlated to
variableresponse inconsistencyor true responseinconsistency
scales of the multidimensional personality questionnaire-brief
form, with no significant differences found between subjects
who were categorized as valid and invalid respondents (41).
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THEORETICAL AND EMPIRICAL SUPPORT FOR PATHOLOGICAL LYING AS A DIAGNOSTIC ENTITY

Finally, although many of the participants indicated they had
never been formally diagnosed with a psychological disorder,
the current study did not specifically compare PL to various
other psychological disorders. Future studies may examine
assessment profiles of people with PL behavior to deter-
mine convergent and discriminant validity related to other
psychopathologies.
Future Directions
If PL is recognized as a diagnostic entity, researchers would
be positioned to examine additional features, etiology, and
effectiveand efficacious treatments. Research may also benefit
from exploring clinicians’experiences in treating individuals
having PL. Future analyses at the biological level may lead to a
deeper understanding of PL. Recognizing PL would equip
practitioners to diagnose and treat the condition, thus allowing
people to seek treatment. Because PL is not a formally rec-
ognized disorder, no systematic studies on the effectiveness
of psychotherapy in treating PL have been conducted (27).
The utility of implementing cognitive-behavioral therapy and
pharmacotherapeutic options for treating PL is worth con-
sideration (27).
In addition to supporting recognition of PL as a diagnostic
entity, the current research adds to deception literature by
establishing parameters that distinguish pathological lying
from normative lying. The current study showed that cate-
gorical distinctions can be made between normative, prolific,
and pathological lying. Thus, this study will assist researchers
investigating the range of lying patterns.
CONCLUSIONS
In sum, the current evidence and theory built on existing case
studies support establishment of PL as a diagnostic entity. The
findings support PL as meeting criteria for a mental disor-
der, with evidence of a unique, valid, and reliable group of
symptoms. We have provided theoretical criteria, etiological
markers, and a definition of PL, which should guide clinicians
in identifying PL. There are individuals who clearly recognize
and report concerns about their own excessive, persistent,
and problematic lying behavior. Currently, there is no di-
agnostic label for these individuals and no specific treatment.
Features of PL are distinct and found beyond the forensic
population. Definition of a diagnosis of PL would pose low
risk of harm and would allow practitioners to formally
identify PL and to provide treatment for people looking for
relief from its symptoms.
AUTHOR AND ARTICLE INFORMATION
Department of Psychology and Sociology, Angelo State University, San
Angelo, Texas (Curtis); Department of Psychology and Philosophy, Texas
Woman’s University, Denton (Hart).
Send correspondence Dr. Curtis (drew.curtis@angelo.edu).
The authors report no financial relationships with commercial interests.
Received December 29, 2019; revisions received March 9 and April 18,
2020; accepted May 12, 2020; published online June 22, 2020.
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