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Puppet Master: Possible Influence of the Parasite Toxoplasma Gondii on Managers and Employees

February 2017
Academy of Management Perspectives 31(1):63-81

DOI:10.5465/amp.2015.0163

Authors:

Prague University of Economics and Business

The article reviews recent literature on the effects of host manipulation by the parasite Toxoplasma gondii (prevalent in about a third of the world’s population) on perception, cognition, and behavior of humans, and on the changes in their physical appearance and personality characteristics. I argue that the mind-affecting parasite paradigm offers many research opportunities for management sciences, especially for organizational psychology and neuroscience. The article summarizes the parasite’s physiological mechanisms of affecting the host; highlights important behavioral effects of the infection in humans; and speculates on the possible impacts on skills and careers of employees and managers, organizational dynamics, intercultural management, and gender work roles. The conclusion shows limitations of the presented speculations and possible directions for future research on Toxoplasma’s effect on organizational dynamics.

Studies on Toxoplasma's Influence on Human Cognitive Functions

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Studies on Toxoplasma's Influence on Human Personality Traits

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There is no data for the countries that are not shaded in the map. The source of country-level statistics is Flegr and Dama (2014). Toxoplasmosis is typically diagnosed by serological tests, which measure levels of antibodies—immunoglobulin G (IgG) or immunoglobulin M (IgM)—in the blood of the tested people. Most of the seroprevalence data comes from women of childbearing age (the seroprevalence is therefore adjusted to a standard age of 22 years). Nevertheless, the seroprevalence reported in the epidemiological literature varies enormously (Chemoh et al., 2013), and in many countries it is now dramatically decreasing, possibly due to a shift in hygiene habits.

…

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rAcademy of Management Perspectives

2017, Vol. 31, No. 1, 63–81.

https://doi.org/10.5465/amp.2015.0163

ARTICLES

PUPPET MASTER: POSSIBLE INFLUENCE OF THE PARASITE

TOXOPLASMA GONDII ON MANAGERS AND EMPLOYEES

PETR HOUDEK

University of Economics in Prague and Jan Evangelista Purkyn ˇ

e University

The article reviews recent literature on the effects of host manipulation by the par-

asite Toxoplasma gondii (prevalent in about a third of the world’s population) on

perception, cognition, and behavior of humans, and on the changes in their physical

appearance and personality characteristics. I argue that the mind-affecting parasite

paradigm offers many research opportunities for management sciences, especially

for organizational psychology and neuroscience. The article summarizes the para-

site’s physiological mechanisms of affecting the host; highlights important behav-

ioral effects of the infection in humans; and speculates on the possible impacts on

skills and careers of employees and managers, organizational dynamics, intercul-

tural management, and gender work roles. The conclusion shows limitations of the

presented speculations and possible directions for future research on Toxoplasma’s

effect on organizational dynamics.

Toxoplasmosis is a disease caused by the uni-

cellular parasite Toxoplasma gondii. This infection

afflicts 30% to 40% of worldwide human pop-

ulation, and the prevalence of toxoplasmosis, un-

like most other pathogens, is high even in some

developed countries (Tenter, Heckeroth, & Weiss,

2000) (see Figure 1). The disease is clinically latent,

and infected people usually do not show any visible

symptoms, so most afflicted people are unaware of

their infection. Nevertheless, knowing the life cycle

and effects of the parasite is useful for organiza-

tional researchers and practicing managers, be-

cause Toxoplasma is able to covertly alter cognition

and personal characteristics of infected individ-

uals. It systematically changes their physical ap-

pearance, their health, and ultimately their ability

to perform at work (Flegr, 2013a, 2013b; Webster,

Kaushik, Bristow, & McConkey, 2013). The aim of

this paper is to show how toxoplasmosis might

influence the cognitive and personality characteristics

of employees and managers, and offer speculations

on the possible impacts of these changes on the

careers of the infected people and on organiza-

tional dynamics.

Toxoplasma affects behavior of infected humans

by manipulating the central nervous system (see

Figure 2), so it can serve as a source of natural case

studies of how and why the hypotheses of orga-

nizational neuroscience are useful in studying orga-

nizational processes and employees’and managers’

decision-making. So far such specific studies have

not been conducted, although using the paradigm of

a mind-affecting parasite does not share the meth-

odological limitations for which organizational neu-

roscience is frequently criticized (Ashkanasy, Becker,

& Waldman, 2014; Butler, O’Broin, Lee, & Senior,

2016; Cropanzano & Becker, 2013; Lindebaum &

Jordan, 2014).

Ashkanasy and colleagues (2014, pp. 909–910)

pointed out four main issues of contention re-

garding the application of neuroscience to orga-

nizational behavior theory and practice: “fear

of reductionism, that organizational neuroscience

seeks to reduce organizational behavior to activ-

ity in particular brain regions or even neurons;

I am very grateful to Jaroslav Flegr, Ludmila Hadincov´

Julie Nov´

akov´

a, Petr Koblovsk´

y, Daniel

Sˇ

tastn´

y, Marek

Vranka, Academy of Management Perspectives editor

Phillip Phan and two anonymous reviewers, and partici-

pants at workshops at J. E. Purkynˇ

e University, the Uni-

versity of Economics in Prague, and Charles University for

their inspiring comments and helpful feedback. This re-

search received support from the grant V

SE IP300040.

written permission. Users may print, download, or email articles for individual use only.

legitimate concerns with limitations of the methods

and technologies that underlie neuroscience re-

search; [that] practical applications of neurosci-

ence may be inappropriate or meaningless, and the

potential for application to issues beyond individuals

(e.g., team-based phenomena) is nonexistent; and

that some applications of neuroscience ... have

all the characteristics of (yet) another manage-

ment fad.”

I address each of these potential problems in

turn. First, the parasite affects the neural and hor-

monal systems directly, so it’s necessary to use

reductionist, “mechanistic”physiological expla-

nations of perception, decision-making, and be-

havior in studying its impact on human behavioral

patterns. Nevertheless, the infected people remain

at their workplaces, in everyday situations instead

of artificial laboratory experiments. We can there-

fore apply predictions from the mechanistic/

physiological explanations to actual behavior of

employees in firms. As Toxoplasma alters primarily

cognitive and personality characteristics, affected

individuals’relationships with other people are

affected too. Second, the effects of infection are

connected to teamwork and organizational man-

agement, not just decisions and behavior of an in-

dividual as is typical for neuroscience laboratory

studies. Third, if the parasite’s influence is truly

genuine, in some cases more so than in others, then

knowledge of its impacts enriches organizational

behavioral theory and holds highly practical insights

for human resources management and organiza-

tional management in general. Finally, although

Toxoplasma infection generally affects people neg-

atively, under some circumstances it can also have

a positive impact (e.g., some Toxoplasma-positive

people have more pronounced extroversion, which

is a predictor of higher status in team contexts;

DesJardins, Srivastava, K ¨

ufner, & Back, 2015), and so

it could enable organizational scholars to observe the

FIGURE 1

Prevalence of Toxoplasmosis (Seroprevalence) Per Country in Percent of Population

There is no data for the countries that are not shaded in the map. The source of country-level statistics is Flegr and Dama (2014).

Toxoplasmosis is typically diagnosed by serological tests, which measure levels of antibodies—immunoglobulin G (IgG) or immuno-

globulin M (IgM)—in the blood of the tested people. Most of the seroprevalence data comes from women of childbearing age (the

seroprevalence is therefore adjusted to a standard age of 22 years). Nevertheless, the seroprevalence reported in the epidemiological

literature varies enormously (Chemoh et al., 2013), and in many countries it is now dramatically decreasing, possibly due to a shift in

hygiene habits

64 FebruaryAcademy of Management Perspectives

selection of Toxoplasma-infected individuals with

induced change of personality for specific organiza-

tional positions or roles.

Furthermore, due to a possibility that the parasite

affects the forms of human cultures and economic

institutions as well (Lafferty, 2006; Maseland, 2013),

the findings about the parasite could be also used in

the field of intercultural or international manage-

ment. (Toxoplasma, as this article will show, can

cause infected people to act impulsively, and toxo-

plasmosis is quite widespread in France, for exam-

ple.) Moreover, the findings can also be used in

general research on decision-making errors and

biases of managers.

While all these research propositions seem to be

long shots (and some of them are truly just specula-

tions, as I highlight later in the review), I believe that

in the area of organizational neuroscience it is true

“that a study of latent toxoplasmosis ... has its best

years ahead”(Flegr, 2013a, p. 161).

Yet methodological and ethical problems prevail

in this paradigm as well. First, it’s not possible to infect

humans in randomized experiments. Therefore, most

evidence of the influence of toxoplasmosis on human

personality and cognition is of a correlational nature,

and as we all know, correlation does not mean causa-

tion. Second, although the effects of toxoplasmosis

are not pathological, the latent infection is chronic

and typically incurable in people. The disease can

create a stigma in infected persons and lead to dis-

crimination against them.

With this as the backdrop, the article proceeds

as follows: I present some basic information on

the protozoan parasite Toxoplasma gondii and the

physiological mechanisms that affect its hosts. The

first part of this systematic review of the parasite’s

influence on humans is focused on changes in the

cognitive abilities of infected people and the possible

impacts of their impaired cognition on their jobs.

The second part of the review concerns permanent

changes in personality characteristics and traits (as

conceptualized by the five-factor model; Goldberg,

1990) or appearance that infected people may un-

dergo. I then speculate how toxoplasmosis may in-

fluence work performance and careers of infected

employees through these changes in personality

traits. This section is followed by a short speculation

on the possible influence of the parasite on cultures.

The conclusion shows the limitations of the pre-

sented inferences and possible future courses of

research on Toxoplasma’s impact on organizational

dynamics.

TOXOPLASMA GONDII, THE MASTER

The objective of Toxoplasma is to make its way

from its intermediate hosts (typically rodents, but

probably all warm-blooded animals) to its final

hosts—cats and other felines (members of the family

Felidae). Only in the digestive system of cats can the

parasite sexually reproduce and spread (through the

cat’s excrement). If an intermediate host is infected

by Toxoplasma, the parasite quickly reproduces

asexually and its oocytes settle in the host’s brain and

other tissues and begin altering the host’s behavior.

These manipulations are sometimes very specific—

for example, infected rats are no longer afraid of cat

odor, but they don’t lose fear of other predatory

species (Lamberton, Donnelly, & Webster, 2008).

Other manipulations are straightforward: The re-

action time of infected animals increases; vigilance

and motor activity deteriorate. Nonetheless, the

infected rats show further risky behavior (Webster,

2007). The chances of a cat catching an infected

rat increase drastically, which means that Toxo-

plasma reaches its final destination (where it sex-

ually reproduces) faster, and the cycle repeats. The

manipulation of hosts increases with the length of

the infection, indicating a causal influence of the

parasite on the changes in its intermediate host’s

FIGURE 2

AToxoplasma Tissue Cyst in the Brain of

a Chronically Infected Mouse

Width of the cyst is about 50 mm; small darker bodies around the

cyst are brain cells. During its life cycle, Toxoplasma gondii con-

verts into various stages with different morphology. There are

many Toxoplasma strains, but the majority in the United States

and Europe fall into three distinct lineages (Saeij, Boyle, &

Boothroyd, 2005). Printed by permission of Jaroslav Flegr.

2017 65Houdek

behavior. They could not be merely the side effects

of an acute infection, which would rather induce

a more pronounced behavioral change at the be-

ginning. It cannot be ruled out completely that the

manipulation by the parasite is a wide-ranging

consequence of a chronic disease—tissue destruc-

tion and the host’s immune system activity (Flegr,

2013a). Nevertheless, Webster, Lamberton, Donnelly,

and Torrey (2006) showed that anti-parasite med-

ications are efficient in preventing related be-

havioral alterations (moreover, medications used

to treat psychiatric diseases possess anti-parasitic

properties, too).

Any warm-blooded animal can be infected by

Toxoplasma, including humans. The infection is

most frequently contracted by consuming poorly

washed vegetables or fruits from places contami-

nated with feline excrement, coming into direct

contact with the excrement, or consuming insuffi-

ciently cooked meat of infected animals (e.g., pork,

lamb, or turkey). That may be the reason why

countries with a tradition of eating undercooked

meat have a higher prevalence of toxoplasmosis (as

do countries with more people working in agricul-

ture, poor hygienic standards, and cats as common

pets).

After a short acute stage that resembles the flu, the

infection quickly enters a latent stage characterized

by the permanent presence of the parasite’s cysts in

the muscles and central nervous system. The chronic

disease is seemingly asymptomatic in most people.

Serious health complications are rare and appear

primarily in prenatal infections (a congenital in-

fection can cause miscarriage or severe impairments

in the newborn) or in patients with weakened im-

munity from HIV/AIDS or immunosuppressants

(after organ transplantation).

Toxoplasma cannot recognize in which host it is

present, so its manipulation affects behavioral

patterns not only in rodents but also in its atypical

hosts, including humans (Webster et al., 2013). For

example, infected men rate the smell of cat urine as

more pleasant than uninfected individuals do (Flegr,

Lenochov´

a, Hodn ´

y, & Vondrov´

a, 2011).

Physiological Mechanisms of Manipulations

Cysts containing Toxoplasma are distributed rela-

tively randomly across the brain (but see McConkey,

Martin, Bristow, & Webster, 2013); in rodents, cysts

are found especially in the olfactory bulbs, the amyg-

dala, the nucleus accumbens, the cerebral cortex, the

cerebellum, the medulla oblongata, the basal ganglia,

and the septohippocampal and perihippocampal

regions (Webster & McConkey, 2010). Cysts can

cause direct neurodegeneration (see similar effects

of cytomegalovirus; Novotn ´

a et al., 2005), but these

pathological processes alone are unlikely to be

responsible for the observed behavioral changes.

This is because important behavioral characteris-

tics are left intact, except for the observed specific

behavioral alterations.

The placement of the cysts in the olfactory bulbs

and in the amygdala is not surprising because the

change in the perception of cat odor is a common

manipulation of Toxoplasma, and because the

amygdala handles stimuli that cause fear. Similarly,

a strong candidate for the location of the parasite in

the brain of a host is the nucleus accumbens, which

has demonstrated a role in a range of behaviors re-

garding rewards, expectations, pleasure, and fear

(Cauda et al., 2011). However, any direct effect of

the parasite in the selected regions relies on the

premise that parasites can locate these regions and

then implement their manipulation with surgical

precision—which does not seem probable. The

handling mechanism is rather an indirect neuro-

transmitter modulation. Toxoplasma causes chem-

ical changes in its immediate surroundings and

thereby influences certain neurons playing a role in

the “targeted”behavior. Thus, it can strengthen or

weaken certain neuronal pathways and make some

physiological and behavior effects more likely than

others (Webster & McConkey, 2010).

The parasite can change the concentration level of

the neurotransmitter dopamine in the brain by local

inflammation of certain neuronal areas. This was

observed physiologically in mice and indirectly in

humans. Infected people are characterized by re-

duced novelty seeking (Flegr et al., 2003; Skallov ´

Kodym, Frynta, & Flegr, 2006), which is a per sonality

trait significantly associated with the dopaminergic

system (Cloninger, Svrakic, & Przybeck, 1993).

Moreover, the genome of Toxoplasma also contains

genes for key enzymes of dopamine synthesis

(Gaskell, Smith, Pinney, Westhead, & McConkey,

2009). Because there is no simple explanation for

why Toxoplasma should have similar enzymes for

itself, it is expected that the parasite induces a release

of dopamine into hosts’tissues to manipulate them

(Prandovszky et al., 2011). Dopamine is involved in

behavior related to getting rewards and avoiding

loss, impulsivity, learning, novelty seeking, and risk

taking (Jocham, Klein, & Ullsperger, 2011; Pine,

Shiner, Seymour, & Dolan, 2010; Sharot, Shiner,

Brown, Fan, & Dolan, 2009). These characteristics

66 FebruaryAcademy of Management Perspectives

undoubtedly have effects in many aspects of organi-

zational life.

The impact of the infection could be significant

with regard to outbreaks of several neurological and

psychiatric diseases associated with a biased func-

tion of the dopaminergic system. For example, hav-

ing toxoplasmosis was found to increase the risk of

schizophrenia 2.7 times, which is approximately

equal to the increased risk of a cannabis user (Torrey,

Bartko, & Yolken, 2012). The influence of toxoplas-

mosis was even identified at the onset of personality

disorders, Parkinson’s disease, Alzheimer’s disease,

obsessive-compulsive disorder, recurrent migraines,

autism, brain tumors, and even depression (for re-

views see Flegr, 2013a; Webster et al., 2013). The rate

of prevalence of toxoplasmosis is correlated with

countries’suicide rates (Ling, Lester, Mortensen,

Langenberg, & Postolache, 2011); women infected

with toxoplasmosis are twice as likely to commit or

attempt suicide than uninfected women (Pedersen,

Mortensen, Norgaard-Pedersen, & Postolache,

2012). This effect is concentrated closer to the

moment of infection (it doesn’t intensify with the

duration of infection), so it appears to be an im-

mediate reaction rather than a cumulative impact

of latent disease.

Many of the above-mentioned psychiatric disor-

ders are associated with depressive states, showing

the possible effect of Toxoplasma on the metabolism

of serotonin. Serotonin is synthesized from trypto-

phan, an amino acid that is a basic nutrient for many

parasites, including Toxoplasma. Stemming from

this, depression thus could be caused by a fattening

parasite (Flegr, 2013a, but see also Healy, 2015). If it

is true that the Toxoplasma is involved in the onset of

depression, it may worsen infected employees’life

satisfaction, and there is no doubt that employees’

psychological well-being heavily influences their

work-related outcomes (Luthans & Youssef, 2007;

Youssef & Luthans, 2007).

Toxoplasmosis may also affect testosterone levels.

Toxoplasma-positive men have a higher concen-

tration of testosterone and Toxoplasma-positive

women have a lower concentration of testosterone

than Toxoplasma-free controls (Flegr, Lindov ´

a, &

Kodym, 2008). The opposite direction of the testos-

terone shifts can explain the observed gender spec-

ificity of behavioral and personal alterations in

Toxoplasma-positive participants (see more in the

following sections). These results could be caused

by the immunosuppressive nature of testosterone,

making men more likely to be infected. On the other

hand, a study (Lim, Kumar, Hari Dass, & Vyas, 2013)

showed that Toxoplasma infection enhances ex-

pression of genes involved in facilitating synthesis of

testosterone, resulting in greater testicular testoster-

one production in male rats. The same mechanism

could work also in humans.

How Do the Puppets Behave? Effects on Cognition

and Working Memory

A manager’s performance (as is most workers’)is

undoubtedly related to his or her mental abilities

(Eggers & Kaplan, 2013; Teece, 2007). General cog-

nitive abilities largely predict both academic and

occupational levels attained and work perfor-

mance, and do so better than any other trait or dis-

position (Kuncel, Hezlett, & Ones, 2004; Schmidt &

Hunter, 2004). It’s not surprising that a third to half

of CEOs attended an elite school, which placed

them in the top 1% of cognitive abilities (Wai &

Rindermann, 2015). Current research on cognitive

ability and performance in the workplace focuses

on finding out which emotional and cognitive

processes—such as bounded attention and perception,

memory, and problem solving—are active in manage-

rial and strategic decision making or which (un)suc-

cessful “cognitive climates”are prevalent within

organizations (Baron, 2006; Foss & Lindenberg,

2013; Hodgkinson & Healey 2011; Houdek, 2016).

Although there aren’t many studies on the impact

of toxoplasmosis on job-related cognition, published

studies thoroughly confirm that even in humans,

toxoplasmosis generally impairs basic cognitive

functions (see Table 1 for a systematic review). The

infected humans aren’t in danger of being caught by

a cat, obviously, though their slower reactions can

cause death or injury. Studies have shown that

Toxoplasma-positive people are more likely to be

involved in traffic accidents and workplace acci-

dents (see Table 1), although the latter relationship

was demonstrated only in small subsamples of

workers from a low social class, so a generalization of

these findings remains questionable. The preferred

explanation of the results is that the negative impacts

of toxoplasmosis will mainly be manifested in al-

ready prone groups or situations and/or contexts

where the basal cognitive strength is weak. This ex-

planation stems from the finding that there is more

frequent and earlier manifestation of Alzheimer’s

disease in people with low cognitive reserves (Stern,

2009).

Just like mice, infected humans have slower re-

actions. In a simple double-blind experiment

(Havl´

cek, Gaˇ

sov´

a, Smith, Zv´

ara, & Flegr, 2001), the

2017 67Houdek

TABLE 1

Studies on Toxoplasma’s Influence on Human Cognitive Functions

Study Country

Type of study

[specific group]

N(Toxoplasma-

positive/control) Methods Findings

Ferreira et al. (2013) Brazil Survey of hospital patients

[children 6–13 years old]

8/92 Scholastic performance test Infected subjects had lower results on

the mathematics subtest of the

scholastic performance test.

Flegr, Havl´

cek, Kodym,

Mal´

y, & Smahel (2002)

Czech

Republic

Survey of subjects

involved in traffic

accidents (case-control)

146/446 Correlation between relative

risk of traffic accidents and

Toxoplasma infection

Infected subjects had increased risk of

traffic accidents.

Flegr, Klose, Novotn´

Berenreitterov´

a, &

Havl´

cek (2009)

Czech

Republic

Prospective cohort study

design [male draftees]

Of 3,890 subjects

29.7% were

Toxo-positive

Correlation between relative

risk of traffic accidents and

Toxoplasma infection

Infected subjects (but only RhD negative)

had increased risk of traffic

accidents.

Flegr, Novotn´

a, Lindov´

a, &

Havl´

cek (2008)

Czech

Republic

Behavioral study 58/278 Reaction time test

(psychomotor performance)

Infected subjects (but only women) had

lower psychomotor performance.

Havl´

cek, Gaˇ

sov´

a, Smith,

Zv´

ara, & Flegr (2001)

Czech

Republic

Double-blind behavioral

study

60/56 Reaction time test

(psychomotor performance)

Infected subjects had decreased

psychomotor performance.

Lanchava, Carlson,

Seb´

ankov´

a, Flegr, &

Nave (2015)

Czech

Republic

Behavioral study [women] 39/40 Financial decision-making

experiment

Infection was not associated with

financial decision making in

females.

Novotn´

a et al. (2008) Czech

Republic

Behavioral study 1st study 41/73; Reaction time test

(psychomotor performance)

Infected subjects (but only RhD negative)

had decreased psychomotor

performance.

2nd study 151/288;

3rd study 95/220

Pˇ

r´

ıplatov´

Seb´

ankov´

a, &

Flegr (2014)

Czech

Republic

Double-blind behavioral

study

44/192 Test of acoustic prepulse

inhibition of simple

reaction times

Infected subjects had prolonged reaction

times to acoustic signals.

Beste, Getzmann,

Gajewski, Golka, &

Falkenstein (2014)

Germany Behavioral study

[seniors, 631]

36/36 Auditory distraction

paradigm

Infected subjects had compromised

attentional allocation and

disengagement.

Gajewski, Falkenstein,

Hengstler, & Golka

(2014)

Germany Double-blind behavioral

study [seniors, 651]

42/42 Battery of neuropsychological

tests

Infected subjects had an impairment of

various aspects of memory.

Stock, Heintschel von

Heinegg, K¨

ohling, &

Beste (2014)

Germany Double-blind behavioral

study

18/18 Stop–change paradigm Infection was not associated with

cognitive control processes (infected

subjects were better at

these tasks).

Alvarado-Esquivel et al.

(2014)

Mexico Cross-sectional survey

(convenience sampling)

71/143 Correlation between clinical

characteristics and

Toxoplasma

infection

Infection was associated with memory

impairment.

Alvarado-Esquivel,

Torres-Castorena,

Liesenfeld, Estrada-

Mart´

ınez, & Urbina-

Alvarez (2012)

Mexico Survey of subjects

involved in work

accidents (case-control)

Of 133 subjects

involved in

accidents, 12 were

Toxo-positive; of 266

control, 20 were

Toxo-positive

Correlation between relative

risk of work accidents and

Toxoplasma infection

Infected subjects (but only those with

low socioeconomic status) had an

increased risk of work

accidents.

68 FebruaryAcademy of Management Perspectives

TABLE 1

(Continued)

Study Country

Type of study

[specific group]

N(Toxoplasma-

positive/control) Methods Findings

Galv´

an-Ram´

ırez et al.

(2013)

Mexico Survey of subjects

involved in traffic

accidents (case-control)

Of 159 subjects

involved in

accidents, 54 were

Toxo-positive; of 164

control, 59 were

Toxo-positive

Correlation between relative

risk of traffic accidents and

Toxoplasma infection

Infected subjects had an increased risk of

traffic accidents.

Sugden et al. (2016)* New

Zealand

Population-representative

birth-cohort study

236/601 Correlation between various

phenotypes and

Toxoplasma infection

Infection was not associated with poor

impulse control or neurocognitive

impairment.

Guenter et al. (2012) Poland Behavioral study 26/44 Battery of neuropsychological

tests

Infection was not associated with any

cognitive impairments.

Kocazeybek et al. (2009) Turkey Survey of subjects

involved in traffic

accidents (case-control)

Of 243 subjects

involved in

accidents, 130 were

Toxo-positive; of 200

control, 56 were

Toxo-positive

Correlation between relative

risk of traffic accidents and

Toxoplasma infection

Infected subjects had an increased risk of

traffic accidents.

Yereli, Balcio˘

glu, &

Ozbilgin (2006)

Turkey Survey of subjects

involved in traffic

accidents (case-control)

Of 185 subjects

involved in

accidents, 60 were

Toxo-positive; of 185

control, 16 were

Toxo-positive

Correlation between relative

risk of traffic accidents and

Toxoplasma infection

Infected subjects had an increased risk of

traffic accidents.

Gale, Brown, Erickson,

Berrett, & Hedges (2015)

USA Population-representative

study

Of 4,178 subjects,

19.1% were Toxo-

positive

Battery of neuropsychological

tests

Infected subjects (but only those with low

socioeconomic status and in certain

racial-ethnic groups) had various

impairments of cognitive functions.

Mendy, Vieira, Albatineh,

& Gasana (2015a)

USA Population-representative

study [children 12–16

years old]

Of 1,755 subjects, 7.7%

were Toxo-positive

Battery of neuropsychological

tests

Infection was associated with lower

reading skills and memory capacities.

Mendy, Vieira, Albatineh,

& Gasana (2015b)

USA Population-representative

study [seniors, 601]

Of 4,485 subjects, 41%

were Toxo-positive

Memory tests Infection was associated with lower

immediate memory.

Pearce, Kruszon-Moran, &

Jones (2014)

USA Population-representative

study

Of 4,234 subjects,

20.9% were Toxo-

positive

Battery of neuropsychological

tests

Infected subjects (but only those with low

socioeconomic status) had various

impairments of cognitive functions.

Note: The above-mentioned studies were selected through the Google Scholar and PubMed databases. Laboratory and field studies, case studies, and surveys estimating the

influence of toxoplasmosis on the cognition of otherwise healthy people were included. The databases were searched using the following keywords: human, Toxoplasma,

toxoplasmosis, cognition, cognitive, memory, attention, perception, reaction, and problem solving. Articlesfrom 1950 to May 2016 were included. The results comprised more than

14,000 references. After excluding unsuitable articles (reviews; conceptual papers; animal studies; in vivo studies; studies on psychiatric, neurological, and other diseases; cross-

country comparative studies; and unpublished studies, typically theses), 41 remained. Another 19 studies were excluded because they didn’t relate directly to cognitive abilities;

they monitored the prevalence of toxoplasmosis in different professions and other groups, or they were duplicates referred to in Table 2. The number of Toxo-positive participants is

an estimate across different serological analyses (i.e., acute and latent infections).

*The study is presented in both systematic reviews.

2017 69Houdek

first of its kind, participants had to press a designated

key as quickly as possible after a certain shape

appeared on the screen. In the first minute of the

experiment, there was no difference in the reaction

times of infected and uninfected participants. After

the first minute, the infected people started getting

significantly slower, which suggests that Toxo-

plasma weakens long-term ability to concentrate.

Other studies have indicated that infected people are

more easily tired or not able to concentrate on longer-

lasting tasks (see Table 1).

Of these studies (see Table 1), 12 found a negative

influence of toxoplasmosis on various cognitive

functions, six found a negative influence only in

certain subgroups of subjects, and four found either

no effect or an opposite effect. However, most of

these studies are conducted in convenience samples

and test multiple variables and thus do bear a large

risk of false positives (Bettis, 2012; Simmons,

Nelson, & Simonsohn, 2011). (On the other hand,

as mentioned earlier, there exists some suspicion

that Toxoplasma increases testosterone levels and

thus stimulates competitiveness in men, so many

tests’results can be skewed away from identifying

negative influence of toxoplasmosis on cognition in

men, because infected men could work harder in the

competitive environment of an experiment.)

The results presented in this section show that

Toxoplasma-positive people have longer reaction

times, they are more easily distracted from th eir long-

term tasks, and their working memory is worse

(Table 1). Good working memory and ability to ex-

ercise cognitive control are of course crucial for pre-

dicting job performance on a number of measures

(Ackerman, Beier, & Boyle, 2005; Tang & Posner,

2009). The infection also appears to be linked with

recklessness (Lindov´

a, Pˇ

r´

ıplatov´

a, & Flegr, 2012). In

sum, it is expected that during prolonged tasks that

require concentration, infected people will achieve

worse outcomes than uninfected individuals.

Nevertheless, the correlative nature of the analyses

allows the interpretation that certain unfavorable

socioeconomic conditions are related to both low

cognitive abilities and a higher risk of being infected

with toxoplasmosis (such as eating unwashed vege-

tables or uncooked meat, living in the countryside,

etc.). The association between infection and cogni-

tive deficits is usually weaker or even disappears

when the covariates of age, socioeconomic status,

and gender are controlled for (Gale, Erickson,

Berrett, Brown, & Hedges, 2016). Cross-sectional

surveys, however, cannot exactly show whether

toxoplasmosis has a direct impact on cognition

(although there is strong evidence that the difference

in personality traits between infected subjects and

controls increases with time since the moment of in-

fection; see below). The relationship between cogni-

tion and toxoplasmosis is reversible and modulated

by many other factors: Low socioeconomic status can

lead to cognitive difficulties (Mullainathan & Shafir,

2013) and a higher risk of being infected with toxo-

plasmosis, or infection can lead to cognitive difficul-

ties and subsequent low social status.

CHANGES IN PERSONAL CHARACTERISTICS

AND PHYSICAL APPEARANCE

Management research has shown that in organi-

zational practice, people with different personality

profiles hold different beliefs and react differently

to work challenges (George, 1992; Raja, Johns, &

Ntalianis, 2004). The first large meta-analysis (Barrick

& Mount, 1991), the results of which have been cor-

roborated by subsequent meta-analyses (Judge, Heller,

& Mount, 2002; Judge, Higgins, Thoresen, & Barrick,

1999), used a five-factor model (Goldberg, 1990),

which has a long influential history of explaining or-

ganizational behavior and will also be used below in

a demonstration of how toxoplasmosis may affect

the discussed personality traits in humans. Barrick

and Mount’s (1991) study found that the trait of

conscientiousness—a persistent, planful, responsible,

and hardworking personality—consistently positively

correlates with various indices of a worker’spro-

ductivity (job proficiency, training proficiency, and

personnel data) across different professions. Further-

more, the trait of extroversion—a sociable, gregarious,

assertive personality craving reward and status—

influences productivity in positions with substantial

social interactions, such as managers and sales.

Extroversion and conscientiousness are also the

strongest predictors of leadership (Judge, Bono,

Ilies, & Gerhardt, 2002). The personality construct

“openness to experience”correlates with perfor-

mance in training proficiency but not anywhere

else. On the other hand, other studies conclude that

openness to experience is strongly related to in-

novation and creativity of workers and with intrinsic

motivation not only at workplaces (George & Zhou,

2001; Shalley, Zhou, & Oldham, 2004).

Conversely, neuroticism—a personality manifest-

ing emotional instability, anxiety, and lack of psy-

chological adjustment—correlates positively with

dissatisfaction at work, low productivity, and in-

ability to lead (Judge, Heller, & Mount, 2002; Judge,

Higgins, Thoresen, & Barrick, 1999).

70 FebruaryAcademy of Management Perspectives

Of the 15 studies listed in Table 2, 14 found some

influence of toxoplasmosis on various personality

traits; only one (large) study found no effect (again,

a number of studies bear a large risk of false posi-

tives). The personality characteristics of infected in-

dividuals change and the impact generally becomes

more severe the longer they are infected, so it is un-

likely that subjects with certain personality profiles

are more prone to Toxoplasma infection (neverthe-

less, without human infection experiments—which

are clearly unethical—it is not possible to decide

whether a genuine causal relation exists between

Toxoplasma infection and personality and other

changes). However, there are disparities in the find-

ings, and toxoplasmosis generally explains only

a small part of the variability.

For example, Skallov´

a et al. (2005) found that

Toxoplasma-positive participants, both men and

women, had lower scores in the psychobiological

factor novelty seeking than Toxoplasma-free partic-

ipants, and that infected subjects had little or no need

for novel stimulation and preferred familiar places,

people, and situations; these results largely confirmed

results obtained by Flegr et al. (2003). Also, Toxoplasma-

positive subjects scored significantly lower on the

test of verbal intelligence than Toxoplasma-free

subjects (although this characteristic might be

explained by different backgrounds of infected and

uninfected individuals). As indicated above, lower

novelty seeking is expected to be associated with

an increased concentration of dopamine in the

brain tissue, a product of the increased synthesis of

dopamine due to Toxoplasma tissue cysts. These

studies also show that Toxoplasma-positive sub-

jects tend to be more organized and methodical and

prefer activities with strict rules and regulations. In

contrast, Lindov´

a et al. (2012) observed lower con-

scientiousness in Toxoplasma-infected subjects,

particularly in men. The relationship between the

pathogen and conscientiousness-related traits is

thus unclear.

Toxoplasma-infected male and female subjects

showed higher extroversion than Toxoplasma-free

subjects (Lindov´

a et al., 2012). Toxoplasma-infected

men tend to be suspicious and jealous, they break

the social rules more often, and they suffer from low

superego strength, but these results are not consis-

tent across studies (see Table 2). As personal qual-

ities significantly influence workplace relations,

leadership, and management skills as well as team-

work performance (Barrick, Stewart, Neubert, &

Mount, 1998; Bradley,Klotz, Postlethwaite, & Brown,

2013), one should expect that changes in personality

characteristics (or altered levels of them) may also be

reflected in corporate practice.

The exact effect of the infection on work perfor-

mance or career growth is difficult to predict because

it is demonstrated on many levels. Moreover, per-

sonality traits and individual skills are linked to their

respective organizational contexts, and their dis/

advantageousness may depend on situational con-

ditions, tasks, and team composition (further dis-

cussion of the topic would be out of the scope of this

article). For example, toxoplasmosis increases ex-

troversion (i.e., social dominance and sociability),

which would be particularly beneficial for sales-

people, managers, and team leaders, but it reduces

cognitive abilities and willingness to try new things.

As it has been proven that leadership skill correlates

with extroversion even more than with intelligence

(Judge, Bono, Ilies, & Gerhardt, 2002; Judge, Colbert,

& Ilies, 2004), the net impact of toxoplasmosis could

be positive for a manager or a leader. Because toxo-

plasmosis lowers conscientiousness, we can specu-

late that infected people would more frequently fail

at their tasks, so that their career dynamics would

look like a supernova, burning bright but perishing

young. Toxoplasma-infected managers can also re-

duce the work satisfaction and productivity of their

subordinates because of their negligence or lack of

a coherent managing system. Infected team members

can limit the performance of the whole team.

The unique questionnaire Toxo94, based on

a pilot study conducted by Flegr (2010), uncovered

even more specific differences between Toxoplasma-

positive and -negative individuals. For example, in-

fected men and women were more likely to agree

with the statements “My instinctive (reflexive) be-

havior under imminent danger is rather slow and

passive. In a situation where most people get alarmed

and instinctively jump aside, I am slow to react,”and

“I believe that some people have the power to impose

their will on others under hypnosis or otherwise.”

Toxoplasma-positive men also agreed more with

the statement “When I am attacked, physically or

otherwise, or when I should fight for something

important, I stop fighting at that moment. It is not

a result of a rational decision not to fight, as in fact I

know that I should continue fighting and I would

like to do so, but my own subconscious betrays me

and I lose the will to fight back.”

The cited statements have many complex mean-

ings; conclusions gained from these questionnaires

are therefore questionable from a psychometric point of

view. Despite that, I would speculate that Toxoplasma-

positive people may manifest paranoid notions about

2017 71Houdek

TABLE 2

Studies on Toxoplasma’s Influence on Human Personality Traits

Study Country Type of study

N(Toxoplasma-

positive/control) Methods Findings

Flegr (2010) Czech

Republic

Convenience

samples

113/330; 68/242; 55/

136; 47/276

Unique questionnaire (Toxo94) Infected subjects expressed various

personality aberrations (see citations in

the main text).

Flegr & Havl´

cek

(1999)

Czech

Republic

Convenience

sample of women

55/136 Cattell’s 16 Personality Factor

Questionnaire

Infected women had higher intelligence,

lower guilt proneness, and possibly also

higher ergic tension.

Flegr & Hrd´

(1994)

Czech

Republic

Convenience

sample

90/248 Cattell’s 16 Personality Factor

Questionnaire

Toxoplasma-positive men had lower

superego strength and protension.

Flegr, Kodym, &

Tolarov´

(2000)

Czech

Republic

Convenience

sample of women

230/0; 55/0 Cattell’s 16 Personality Factor

Questionnaire

Affectothymia, surgence, high superego

strength, parmia, and protension were

correlated with the length of the infection.

Flegr, Preiss, &

Klose (2013)

Czech

Republic

Survey of military

personnel

154/337 N-70 and NEO-PI-R Questionnaire;

Wiener Matrizen-Test of intelligence

Infected subjects expressed lower levels of

potentially pathognomic factors,

measured with the N-70 questionnaire,

and neuroticism. Toxoplasma-infected

subjects expressed lower intelligence

score (while RhD-negative).

Flegr et al.

(2003)

Czech

Republic

Survey of military

personnel

229/628 Cloninger’s Temperament and Character

Inventory

Toxoplasma-positive subjects had lower

novelty seeking, impulsiveness,

extravagance, and disorderliness scores.

Infected subjects also had lower IQs.

Flegr, Zitkov´

Kodym, &

Frynta (1996)

Czech

Republic

Convenience

sample

103/291 Cattell’s 16 Personality Factor

Questionnaire

Infection in men was positively correlated

with low superego strength, protension,

guilt proneness, and group dependency.

For women, the prevailing traits were

affectothymia, alaxia, and untroubled

adequacy and self-sufficiency.

Lindov´

a et al.

(2010)

Czech

Republic

Convenience

sample

56/239 Experimental economic games Infected men were less cooperative and

infected women were more cooperative

compared to their uninfected

counterparts.

Lindov´

a et al.

(2006)

Czech

Republic

Double-blind

testing

(convenience

sample)

49/214 Cattell’s 16 Personality Factor

Questionnaire

Infected men scored significantly lower in

conscientiousness and self-control than

uninfected men; a trend in the opposite

direction was observed in women.

Infected men scored lower in warmth

than uninfected men, whereas there was

no difference in women.

Lindov´

Pˇ

r´

ıplatov´

a, &

Flegr (2012)

Czech

Republic

Convenience

sample

47/276 NEO-PI-R Questionnaire Toxoplasma-infected male and female

subjects had higher extroversion and

lower conscientiousness.

Novotn´

a et al.

(2005)

Czech

Republic

Survey of military

personnel

Of 533 subjects, 25.0%

were Toxo-positive

Cloninger’s Temperament and Character

Inventory; Eysenck’s lie scale

Toxoplasma-positive subjects had lower

novelty-seeking scores.

72 FebruaryAcademy of Management Perspectives

TABLE 2

(Continued)

Study Country Type of study

N(Toxoplasma-

positive/control) Methods Findings

Skallov´

a et al.

(2005)

Czech

Republic

Survey of blood

donors

Of 290 subjects, 61.2%

were Toxo-positive

Cloninger’s Temperament and Character

Inventory; Eysenck’s lie scale

Toxoplasma-positive subjects had lower

novelty-seeking scores.

Cook et al.

(2015)

Germany Survey of healthy

controls as a part

of a case-control

study

475/474 Questionnaire for Measuring Factors of

Aggression; Disinhibition subscale of

the Sensation Seeking Scale

Infection was associated with higher

reactive aggression scores among women

but not among men. Infection was also

associated with higher impulsive

sensation-seeking among younger men.

Khademvatan

et al. (2013)

Iran Convenience

sample

112/125 Cattell’s 16 Personality Factor

Questionnaire

Infected women had higher apprehension,

privateness, and tension scores and lower

openness-to-change scores. Infected men

had higher vigilance and mistrust scores.

Sugden et al.

(2016)*

New

Zealand

Population-

representative

birth-cohort

study

236/601 Correlation between various tests and

questionnaires and Toxoplasma

infection

Infection was not associated with any

personality aberrations.

Note: The above-mentioned studies were selected through the Google Scholar and PubMed databases. Laboratory and field studies, case studies, and surveys estimating the

influence of toxoplasmosis on the personality traits of otherwise healthy people were included (studies estimating influence on psychiatric and mental diseases and personality

disorders were not targeted, as they are outside the scope of this paper). The databases were searched using the following keywords: human, Toxoplasma, toxoplasmosis,

personality, and traits. Articles from 1950 to May 2016 were included. The results comprised more than 12,000 references.After excluding unsuitable articles (reviews; conceptual

papers; animal studies; in vivo studies; studies on psychiatric, neurological, and other diseases; cross-country comparative studies; and unpublished studies, typically theses), 42

remained. Another 27 were excluded because they didn’t relate directly to personality traits; they monitored the prevalence of toxoplasmosis in different professions and other

groups, or they were duplicates referred to in Table 1. The number of Toxo-positive participants is an estimate across different serological analyses (i.e. acute and latent infections).

*The study is presented in both systematic reviews.

2017 73Houdek

processes in organizations and consequently fall vic-

tim to an abusive supervisor (Chan & McAllister,

2014). As noted by De Vries and Miller (1986,p. 271):

“[F]eelings of guilt, worthlessness, and inadequacy

are pervasive. Individuals downgrade themselves;

they are self-deprecating and feel inferior to others,

claiming a lack of ability and talent. They abdicate

responsibility. A sense of helplessness and hope-

lessness prevails. External sources for sustenance are

needed to combat insecurity.”

Effects on Work Performance

In studying the impact of personality characteris-

tics on workplace behavior, leadership, and pro-

ductivity, organizational neuroscience can use the

quite specific influence of toxoplasmosis on the pro-

duction of the sex hormone testosterone. Its impacts

on personality characteristics (decision making and

behavior) and appearance are well documented

(Zitzmann & Nieschlag, 2001). Some studies have

found that Toxoplasma-positive men had higher

testosterone levels than non-infected men (Flegr,

Lindov´

a, & Kodym, 2008; Zghair, Al-Qadhi, &

Mahmood, 2015). Infected women,on theother hand,

had lower levels of the hormone (but see Shirbazou,

Abasian, and Meymand, 2011).

High levels of testosterone have been closely linked

to perceived social status (Eisenegger, Haushofer, &

Fehr, 2011). It plays a significant rolein willingness to

take risks, leadership, and entrepreneurship (Apicella

et al., 2008; Brañas-Garza & Rustichini, 2011; Garbarino,

Slonim, & Sydnor, 2011) and, based on other evidence,

also in impulse control, an increase in planning and

executive abilities (Dreber, Gerdes, Gr¨

ansmark, & Little,

2013), and willingness to engage in antisocial and/or

corrupt behavior (Bendahan, Zehnder, Pralong, &

Antonakis, 2015). High levels of testosterone are also

negatively related to the accuracy with which people

infer the thoughts and feelings of others (Ronay &

Carney, 2013).

Toxoplasma-positive men also appear more

masculine and dominant to women (Hodkov´

Kolbekov´

a, Skallov´

a, Lindov´

a, & Flegr, 2007). For

a person who wants to be a successful leader, it could

be more important to just appear authoritative and

convincing than to actually possess such personality

traits, because specific physical traits are robustly

associated with aggressive and self-interested behav-

ior (Haselhuhn, Wong, Ormiston, Inesi, & Galinsky,

2014; Spisak, Homan, Grabo, & Van Vugt, 2012).

Manipulative effects of Toxoplasma are related to an

increase in facial masculinity, and studies have

confirmed that managers who have more masculine

facial features indeed have higher salaries and work

for more successful companies (Rule & Ambady,

2008; Wong, Ormiston, & Haselhuhn, 2011).

In the case of testosterone, two contradictory ef-

fects of Toxoplasma on behavior make the final

impact difficult to predict. For example, better per-

formance (in the sense of higher profitability) for

a broker depends on his (only men were studied)

higher level of testosterone (Coates & Herbert, 2008),

which is boosted by Toxoplasma, but as the disease

also slows down reaction times, the real-life influ-

ence would be mixed. In summary, we can speculate

that Toxoplasma-positive people can achieve high

positions, but their performance may decline due to

a decrease in conscientiousness, increased neuroti-

cism, and possible health risks. Because of the dif-

ferent effect of toxoplasmosis on testosterone in men

(increased levels) and women (decreased levels), it’s

even possible that toxoplasmosis may be a partial

culprit in the inequality of men and women in

leading positions (see the next section for more in-

formation on toxoplasmosis and gender work roles).

I believe that toxoplasmosis offers an informative

variable in the psychological and neuroscientific

model of the effects of personality, cognitive traits,

and even physical appearance on human capital

and thus on organizational outcomes. It can help

improve identification methods in research on

the impact of personality characteristics on career

outcomes and on teams’and firms’inner workings

(Borghans, Duckworth, Heckman, & Ter Weel,

2008; Daly, Harmon, & Delaney, 2009; Heckman,

2011). If it is true that the parasite gradually and

significantly alters certain aspects of personality

characteristics by manipulating neural and hor-

monal systems of humans, it should be possible to

observe differences in decision making and actions

of infected employees and managers in the orga-

nizational environment compared to those not

infected.

These observations should be identifiable at the

firm, region, state, and country levels, as the preva-

lence of toxoplasmosis varies significantly between

and within countries. For example, in the United

States age-adjusted seroprevalence is higher in the

Northeast (29.2%) thanin the South (22.8%), Midwest

(20.5%), or West (17.5%) (Jones et al., 2001).

INTERCULTURAL MANAGEMENT

On a national level, a higher proportion of the

population infected with toxoplasmosis is associated

74 FebruaryAcademy of Management Perspectives

with stronger neuroticism (Lafferty, 2006). Lafferty

also showed associations between a prevalence of

toxoplasmosis and uncertainty avoidance and mas-

culine sex roles, but those results were not robust. It is

possible that cultural dimensions alter individual

personality through situational or educational con-

ditioning and/or experience and that an aggregate

national personality might be created through the

collective behavior of individuals with a specific

personality (Hofstede & McCrae, 2004). The same way

that infected individuals systematically show evi-

dence of certain personality characteristics, nations

where toxoplasmosis is more frequent demonstrate

these same tendencies as well. What are the charac-

teristics of nations with higher prevalence of toxo-

plasmosis? Lafferty concluded:

Individuals in populations that are “masculine”in the

sex-role cultural dimension reinforce traditional

gender work roles gender differentiation, and have

a higher focus on ego, ambition, money, material

possessions, self-achievement, and work than on re-

lationships, people, social support, and quality of

life. Individuals in populations that rate high in the

cultural dimension of uncertainty avoidance feel

threatened by uncertain or unknown situations,

leading to a rule oriented society geared to reduce

uncertainty. (2006, p. 2753; inner references omitted)

However, similar cross-country analyses suffer

from a strong endogeneity problem in the causality

direction and in operating variables (moreover, the

associations between personality shifts and Toxoplasma-

infected individuals differ between men and women).

Nevertheless, after carefully controlling for deter-

minants of the prevalence of toxoplasmosis in the

population, such as climate, urbanization, level of

sanitation, the consumption of meat, and religion (in

some countries religions promote vegetarianism and

toxoplasmosis is rare), the prevalence of Toxo-

plasma may be a suitable instrument for monitoring

the impact of cultural patterns on organizations’in-

ner workings, business practices, or economics in-

stitutions (Maseland, 2013), and it might help to

explain a huge variation in management practices

across organizations in different countries (Bloom,

Genakos, Sadun, & Van Reenen, 2012). As the

prevalence of toxoplasmosis is high even in some

developed countries (its prevalence is largely inde-

pendent from the economic well-being of nations), it

can be used to decrease the risk of misidentifying

the influence of other biological factors on economic,

cultural, or business variables (Bonds, Dobson, &

Keenan, 2012).

Research focusing on whether varying prevalence

of toxoplasmosis within a country can explain the

specifics of regional (business) cultures would be

methodologically purer and more useful. This data,

however, is currently lacking.

CONCLUSION

The cited literature suggests that Toxoplasma-

positive individuals have specific personality

differences compared with the non-infected pop-

ulation, and that such differences could be caused

by physiological manipulation by the parasite (al-

though in some cases there is still a probability that

people with certain personalities have a higher

likelihood of getting infected). Toxoplasma-positive

individuals have slower reaction times, they are

more easily distracted, and their working mem-

ory is worse. Toxoplasma may decrease an in-

dividual’s life satisfaction. Infected people more

often believe that their instinctive behavior under

imminent danger is rather slow and passive, and

that some people have the power to impose their

will on others. They also believe that when they

are attacked, they stop fighting because their own

subconscious betrays them. Infected men have

higher levels of testosterone, and their physical

appearance is portrayed as more masculine and

dominant. Toxoplasma thus could offer a suitable

model for research on the influence of personality

traits and cognitive skills on individual work perfor-

mance and on organizational outcomes. At pres-

ent, however, there are no studies on the effects of

toxoplasmosis in the context of an organizational

environment.

Utilization of the Toxoplasma model in organiza-

tional neuroscience (or in organizational research in

general) certainly has several limitations. Even

though some impacts of the disease on physiological

mechanisms of dopamine, serotonin, and testoster-

one have been demonstrated (Flegr, 2013b), further

research on exactly which chemical and physiolog-

ical processes Toxoplasma uses to manipulate its

human victims is only at its beginning. For example,

manifestation of the disease depends on the RhD

blood group (Novotn´

a et al., 2008). A recent study

(Hari Dass & Vyas, 2014) found that Toxoplasma is

able to cause specific epigenetic changes in medial

amygdala circuits. Amygdala circuits are, inter alia,

responsible for the sexual behavior of animals; ap-

parently, cats are no longer perceived as a threat by

an infected rat, but instead become a sexually at-

tractive stimulus.

2017 75Houdek

Furthermore, Tan et al. (2015) showed that in-

fection with Toxoplasma increases the propensity of

infected rats to make more impulsive choices. Their

study concludes: “T. gondii infection ... represents

a behavioural syndrome consisting of reduced innate

fear, increased sexual attractiveness and greater de-

lay aversion; all hallmarks of a ‘carpe diem’animal

personality”(Tan et al., 2015, p. 5). As of now there is

only one study that has tested the parasite’s impact

on sexual and/or mating behavior of humans (Flegr &

Kuba, 2016). Although this is just speculation, toxo-

plasmosis could influence the quality of relationships

between men and women in workplaces or the prev-

alence of sexual harassment in firms (as infected men

have higher testosterone levels and infected women

tend to exhibit more warmth).

It is not evident whether toxoplasmosis influences

other personality traits such as creativity, self-

ishness, honesty, personal integrity, and the dark

triad personality traits (narcissism, Machiavellian-

ism, and psychopathy). It can also be expected (as

many of the cited studies indicate) that with controls

on covariates such as personal background, de-

mographics, education, and training, the effects of

the parasite on personality are not that strong, espe-

cially not in the corporate environment. Also, the

reviewed literature presents contradictory findings,

some of which could be false positives due to pub-

lication bias. More replications of relevant studies

are necessary (see Byington and Felps, 2016, for

a more general review of the credibility crisis in

management sciences).

Research on the behavioral demonstration of the

impacts of toxoplasmosis also uses specific groups of

participants (usually students, seniors, pregnant

women, or soldiers), which makes it difficult to

generalize the findings to the general population or

specifically to the business world (although this

issue is common in neuroscientific research). Psy-

chological and cognitive tests are relatively context-

specific, and in most cases questionnaire-based with

an absence of real incentives or trade-offs. It is not

possible to predict how the proposed findings would

end up in the high-stakes multitasking environment

of firms.

Obviously, there are ethical problems as well

(Lindebaum, 2013). Toxoplasma-positive people

could be discriminated against when their infection

becomes known. Nevertheless, knowledge of one’s

own infection should lead to higher awareness of

systematic biases and tendencies that are connected

to toxoplasmosis. Mindfulness training or cognitive

behavioral therapy sessions would be advisable for

some infected individuals. Conversely, if people

knew about their disease and outcomes connected

with it, it could make them adopt an “infected

identity,”and they might start rationalizing their

own mistakes, failures, and lapses (Dijksterhuis &

van Knippenberg, 1998; Vranka & Houdek, 2015).

Another open question is whether toxoplasmosis

should be treated as a preexisting condition in the

realm of legal matters (insurance, health, tort and

criminal law, etc.).

There are many other microorganisms that can

affect some aspects of the human mind and/or be-

havior (Kramer & Bressan, 2015). For instance, the

cytomegalovirus may alter the personality of in-

fected subjects (Novotn´

a et al., 2005), and gut bac-

teria may play a role in anxiety and depression

(Mayer, Knight, Mazmanian, Cryan, & Tillisch, 2014)

or in processing emotions and sensations (Tillisch

et al., 2013). There is even a (small) possibility that

the influenza virus could modify human social be-

havior before the onset of symptoms (Reiber et al.,

2010). Future studies should verify the robustness of

these observed effects and investigate their relevance

to organizational and management research.

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Petr Houdek (petr.houdek@gmail.com) is a Ph.D. candidate

in business economics and management at the University of

Economics in Prague, Czech Republic; he is also a Ph.D.

candidate in theoretical an d evolutionary biology at Charles

University in Prague. He was appointed as an assistant

professor at the Faculty of Social and Economic Studies at J.

E. Purkynˇ

e University in ´

Ust´

ınad Labem, Czech Republic.

His primary research interests include behavioral econom-

ics, social psychology, and management sciences.

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Neurodiversity in (Not Only) Public Organizations: An Untapped Opportunity?

Article

Full-text available

Jan 2022

Petr Houdek

This perspective shows how neurodiversity can increase public organizations’ innovations and output quality. Studies from business and entrepreneurship fields are used to argue that public organizations may prosper if they recruit neurologically atypical individuals. Their unique thinking styles, coping strategies, and life experiences can lead to public services innovation. The management of public organizations through neurodiversity programs may gain competencies benefiting all employees. However, the promotion of neurodiversity cannot be achieved without demanding changes in organizational culture. The article also illustrates the benefits of neurodiversity using the example of a neurogenerative disease (toxoplasmosis).

Two Billion Infected: An Inexpensive Method to Measure Latent Toxoplasmosis and its Economic Consequences

Preprint

Full-text available

Jul 2024

Over two billion people worldwide are infected with the protozoan Toxoplasma gondii, which influences human behavior and cognition. Standard diagnosis methods involve costly medical tests, which prevents widespread testing and hinders the study of the infection's effects. We propose and validate an inexpensive and easy-to deploy diagnostic method for latent Toxoplasmosis infections using response times and finite-mixture models. A clinical study showed that the method is sensitive and accurate. A large, representative UK study showed that the infection's consequences are relevant and pervasive, both economically (decrease in yearly income and employment) and behaviorally (increase in risky behaviors, stress, and depression).

The deep roots of cross-cultural differences in organizational behavior: Do human resource management education has to respect them?

Article

Sep 2023

Petr Houdek

This paper delves into the deep-rooted factors causing cross-cultural differences and their subsequent impact on the effectiveness of human resource practices in organizations. Drawing from a thematic review of findings from diverse fields such as developmental economics, anthropology, and linguistics, the study explores how historical events, language, geography, and biology influence individual ethics, preferences, and decision-making styles. Multiple conceptual frameworks are introduced to guide the integration of these deep-rooted factors into cross-cultural management education. The article suggests several research directions to enhance human resource management and cross-cultural management education. The emphasis is placed on the importance for researchers and educators in the field to employ constructs and methodologies from various disciplines to comprehend the origins and enduring nature of cross-cultural organizational behavior differences. Without understanding the underlying reasons for cross-cultural differences, intercultural management cannot be practiced effectively. Despite the insights provided, it's crucial to acknowledge the currently limited research connecting historical, biological, or linguistic factors to modern organizational outcomes. This limitation makes the provided recommendations largely conjectural.

Establishment of a murine model of congenital toxoplasmosis and validation of a qPCR assay to assess the parasite load in maternal and fetal tissues

Article

Full-text available

Feb 2023

Toxoplasma gondii is the causative agent of toxoplasmosis, a disease that affects warm-blooded animals and one third of the human population worldwide. Pregnant women who have never been exposed to the parasite constitute an important risk group, as infection during pregnancy often leads to congenital toxoplasmosis, the most severe form of the disease. Current therapy for toxoplasmosis is the same as it was 50 years ago and has little or no effect when vertical transmission occurs. Therefore, it is urgent to develop new strategies to prevent mother-to-fetus transmission. The implementation of experimental animal models of congenital toxoplasmosis that reproduces the transmission rates and clinical signs in humans opens an avenue of possibilities to interfere in the progression of the disease. In addition, knowing the parasite load in maternal and fetal tissues after infection, which may be related to organ abnormalities and disease outcome, is another important step in designing a promising intervention strategy. Therefore, we implemented here a murine model of congenital toxoplasmosis with outbred Swiss Webster mice infected intravenously with tachyzoites of the ME49 strain of T. gondii that mimics the frequency of transmission of the parasite, as well as important clinical signs of human congenital toxoplasmosis, such as macrocephaly, in addition to providing a highly sensitive quantitative real-time PCR assay to assess parasite load in mouse tissues. As the disease is not restricted to humans, also affecting several domestic animals, including companion animals and livestock, they can also benefit from the model presented in this study.

Le Petit Machiavellian Prince: Effects of Latent Toxoplasmosis on Political Beliefs and Values

Article

Full-text available

Jul 2022

Humans infected by Toxoplasma gondii express no specific symptoms but manifest higher incidence of many diseases, disorders and differences in personality and behavior. The aim of this study was to compare the political beliefs and values of Toxoplasma-infected and Toxoplasma-free participants. We measured beliefs and values of 2315 responders via an online survey (477 Toxoplasma-infected) using the Political Beliefs and Values Inventory (PI34). This study showed Toxoplasma-infected and Toxoplasma-free participants of our cross-sectional study differed in three of four factors of PI34, scoring higher in Tribalism and lower in Cultural liberalism and Anti-Authoritarianism. We found sex differences in political beliefs associated with Toxoplasma infection. Infected women scored higher in tribalism and lower in cultural liberalism, compared with the Toxoplasma-free control group, while infected men scored higher in economic equity. These results fit with sexual differences in behavior and attitude observed after toxoplasmosis infection. Controlling for the effect of worse physical health and mental health had little impact, suggesting that impaired health did not cause these changes. Rather than adaptation to prevalence of parasites, as suggested by parasite-stress theory, the differences might be side-effects of long-term mild inflammatory reaction. However, to get clear picture of the mild inflammation effects, more research focused on different infectious diseases is needed.

Parasite Biodiversity

Article

Full-text available

Jan 2021

A parasite is an organism that lives in an intimate and durable relationship with its host and imposes a cost on that host, in terms of its ability to survive, grow, and/or reproduce. Despite the fact that more than 40% of animal species are parasites, parasitism is rarely discussed in introductory biology courses. This may be because parasites are often hidden within their hosts—and therefore easy to ignore. But parasites have important roles to play in ecosystems and we ignore them at our own peril. In this module, students have the opportunity to discover the hidden world of parasites: they will come face to face with living parasites, learn about what differentiates parasites from free-living species, observe some common adaptations to a parasitic lifestyle, explore the ecological role of parasites in food webs, and assess how parasite abundance might change in a changing world. To accomplish these goals, this module includes an introductory PowerPoint presentation (including a video of parasite ecologist Dr. Chelsea L. Wood delivering this introductory lecture) and two exercises. The first exercise is a wet lab that involves dissecting an easy (and disturbing) source of live parasite material: fresh fish from your local seafood market. The second exercise is a computer lab that will allow students to engage with real data to answer the question: how do human impacts on ecosystems change the abundance of parasites in wildlife? This module will introduce students to the basics of parasite ecology and provide an opportunity to practice their data analysis and interpretation skills.

Modeling links between corn production and beef production in the United States: a systems thinking exercise using mental modeler.

Chapter

Full-text available

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An inexpensive method to measure latent toxoplasmosis and its behavioral consequences

Article

Feb 2025

Potential and challenges for using neuroscientific tools in strategic management studies

Article

Full-text available

Apr 2022

Purpose The purpose of this study is to understand how neuroscientific tools are used and discussed in ongoing research on strategy in organizations. Design/methodology/approach The authors used a bibliometric study of bibliographic pairing to answer the research question. They collected data from the Web of Science and Scopus databases using the keywords “neuroscience*,” “neurostrategy*” and “neuroscientific*.” Findings This study presents a framework that relates fundamental aspects discussed in current research using neuroscientific tools: Neuroscience and its research tools in organizations; emotions and information processing; interdisciplinary application of neuroscientific tools; and moral and ethical influences in the leaders' decision-making process. Research limitations/implications The inclusion of neuroscientific tools in Strategic Management research is still under development. There are criticisms and challenges related to the limitations and potential to support future research. Practical implications Despite recognizing the potential of neuroscientific tools in the mind and brain relationship, this study suggests that at this stage, because of criticisms and challenges, they should be used as support and in addition to other traditional research techniques to assess constructs and mechanisms related to strategic decisions and choices in organizations. Social implications Neuroscientific methods in organizational studies can provide insights into individual reactions to ethical issues and raise challenging normative questions about the nature of moral responsibility, autonomy, intention and free will, offering multiple perspectives in the field of business ethics. Originality/value In addition to presenting the potential and challenges of using scientific tools in strategic management studies, this study helps create methodological paths for studies in strategic management.

Le Petit Machiavellian Prince: Effects of latent toxoplasmosis on political beliefs and values

Preprint

Full-text available

Oct 2021

Humans infected by Toxoplasma gondii express no specific symptoms but manifest higher incidence of many diseases, disorders and differences in personality and behaviour. The aim of this study was to compare the political beliefs and values of Toxoplasma-infected and Toxoplasma-free participants. We measured beliefs and values of 2315 responders via an online survey (477 Toxoplasma-infected) using the Political Beliefs and Values Inventory (PI34). This study showed Toxoplasma-infected and Toxoplasma-free participants of our cross-sectional study differed in three of four factors of PI34, scoring higher in Tribalism and lower in Cultural liberalism and Anti-Authoritarianism. We found sex differences in political beliefs associated with Toxoplasma infection. Infected women scored higher in tribalism and lower in cultural liberalism, compared with the Toxoplasma-free control group, while infected men scored higher in economic equity. These results fit with sexual differences in behaviour and attitude observed after toxoplasmosis infection. Controlling for the effect of worse physical health and mental health had little impact, suggesting that impaired health did not cause these changes. Rather than adaptation to prevalence of parasites, as suggested by parasite-stress theory, the differences might be side-effects of long-term mild inflammatory re-action, although definitive conclusions cannot be reached due to lack of relevant literature.

When Openness to Experience and Conscientiousness Are Related to Creative Behavior: An Interactional Approach

Article

Full-text available

Jun 2001

This study adopted an interactional approach to understanding how 2 of the Five-Factor traits, openness to experience and conscientiousness, are related to creative behavior in the workplace. Openness to experience is theorized to result in high levels of creative behavior and conscientiousness is theorized to result in low levels of creative behavior when the situation allows for the manifestation of the trait influences. More specifically, the authors hypothesized that openness to experience would result in high levels of creative behavior if feedback valence were positive and job holders were presented with a heuristic task that allowed them to be creative. The authors also hypothesized that conscientiousness would result in low levels of creative behavior if supervisors engaged in close monitoring and coworkers were unsupportive. The authors tested their hypotheses in a sample of office workers, and 5 out of the 6 hypotheses were supported.

The Relation of Toxoplasma Infection and Sexual Attraction to Fear, Danger, Pain, and Submissiveness

Article

Full-text available

Aug 2016

Behavioral patterns, including sexual behavioral patterns, are usually understood as biological adaptations increasing the fitness of their carriers. Many parasites, so-called manipulators, are known to induce changes in the behavior of their hosts to increase their own fitness. Such changes are also induced by a parasite of cats, Toxoplasma gondii. The most remarkable change is the fatal attraction phenomenon, the switch of infected mice’s and rat’s native fear of the smell of cats toward an attraction to this smell. The stimuli that activate fear-related circuits in healthy rodents start to also activate sex-related circuits in the infected animals. An analogy of the fatal attraction phenomenon has also been observed in infected humans. Therefore, we tried to test a hypothesis that sexual arousal by fear-, violence-, and danger-related stimuli occurs more frequently in Toxoplasma-infected subjects. A cross-sectional cohort study performed on 36,564 subjects (5,087 Toxoplasma free and 741 Toxoplasma infected) showed that infected and noninfected subjects differ in their sexual behavior, fantasies, and preferences when age, health, and the size of the place where they spent childhood were controlled (F(24, 3719) ¼ 2.800, p < .0001). In agreement with our a priori hypothesis, infected subjects are more often aroused by their own fear, danger, and sexual submission although they practice more conventional sexual activities than Toxoplasma-free subjects. We suggest that the later changes can be related to a decrease in the personality trait of novelty seeking in infected subjects, which is potentially a side effect of increased concentration of dopamine in their brain.

Solutions to the Credibility Crisis in Management Science

Article

Full-text available

Mar 2017

This article argues much academic misconduct can be explained as the result of social dilemmas occurring at two levels of Management science. First, the career benefits associated with engaging in Noncredible Research Practices (NCRPs) (e.g. data manipulation, fabricating results, data hoarding, undisclosed HARKing) result in many academics choosing self-interest over collective welfare. These perverse incentives derive from journal gatekeepers who are pressed into a similar social dilemma. Namely, an individual journal’s status (i.e. its “impact factor”) is likely to suffer from unilaterally implementing practices that help ensure the credibility of Management science claims (e.g. dedicating journal space to strict replications, crowd-sourcing replications, data submission requirements, in-house analysis checks, registered reports, Open Practice badges). Fortunately, research on social dilemmas and collective action offers solutions. For example, journal editors could pledge to publish a certain number of credibility boosting articles contingent on a proportion of their “peer” journals doing the same. Details for successful implementation of conditional pledges, other social dilemma solutions – including actions for Management academics who support changes in journal practices (e.g. reviewer boycotts / buycotts), and insights on credibility supportive journal practices from other fields are provided.

What Comes to a Manager’s Mind: Theory of Local Thinking

Article

Full-text available

Mar 2016
J MANAGE INQUIRY

Petr Houdek

This article develops a model of local thinking in managerial decision making. According to the concept, attention is drawn by selectively salient factors or recalls in specific decision-making contexts. Although decision makers are aware of the changing conditions, they do not make a sufficient mental correction for the fact that the relevance of these factors is not generalized. They overestimate the importance of an option that “easily comes to one’s mind”: They excessively extrapolate from their experiences and extreme news, succumb to reference points and imprinting. The usefulness of the concept of local thinking in explaining decisions taken by managers is demonstrated by a short conceptual review of several empirical studies on local economic and natural shocks, negotiation of bank loans, expert forecasts, workers’ compensations, and gender equality. The conclusion brings speculations about further implications of the theory for organizational research.

Is Toxoplasma Gondii Infection Related to Brain and Behavior Impairments in Humans? Evidence from a Population-Representative Birth Cohort

Article

Full-text available

Feb 2016
PLOS ONE

Background: Toxoplasma gondii (T. gondii) is a protozoan parasite present in around a third of the human population. Infected individuals are commonly asymptomatic, though recent reports have suggested that infection might influence aspects of the host's behavior. In particular, Toxoplasma infection has been linked to schizophrenia, suicide attempt, differences in aspects of personality and poorer neurocognitive performance. However, these studies are often conducted in clinical samples or convenience samples. Methods/results: In a population-representative birth-cohort of individuals tested for presence of antibodies to T. gondii (N = 837) we investigated the association between infection and four facets of human behavior: neuropsychiatric disorder (schizophrenia and major depression), poor impulse control (suicidal behavior and criminality), personality, and neurocognitive performance. Suicide attempt was marginally more frequent among individuals with T. gondii seropositivity (p = .06). Seropositive individuals also performed worse on one out of 14 measures of neuropsychological function. Conclusion: On the whole, there was little evidence that T. gondii was related to increased risk of psychiatric disorder, poor impulse control, personality aberrations or neurocognitive impairment.

False-positive psychology: Undisclosed flexibility in data collection and analysis allows presenting anything as significant

Article

Full-text available

Jan 2011

The data includes measures collected for the two experiments reported in “False-Positive Psychology” [1] where listening to a randomly assigned song made people feel younger (Study 1) or actually be younger (Study 2). These data are useful because they illustrate inflations of false positive rates due to flexibility in data collection, analysis, and reporting of results. Data are useful for educational purposes.

PSYCHOLOGICAL FOUNDATIONS OF DYNAMIC CAPABILITIES: REFLEXION AND REFLECTION IN STRATEGIC MANAGEMENT.

Article

Aug 2009

We revisit the psychological underpinnings of Teece's (2007) framework of dynamic capabilities development in the light of advances in social cognitive neuroscience and neuroeconomics. We argue that dynamic capabilities are based on a blend of effortful forms of analysis and the skilled utilization of less deliberative, intuitive processes, which enables firms to harness managers' cognitive and emotional capacities.

The role of personality in organizational life: Issues and evidence

Article

Jan 1992

J.M. George

A psychobiological model of temperament and character

Article

Jan 1998

Robert Cloninger

Effects of Toxoplasma gondii infection on plasma testosterone and cortisol level and stress index on patients referred to Sina Hospital, Tehran

Article

Jan 2011

Introduction and objective: Toxoplasma gondii is an intra cellular protozoan parasite which infects 30 to 60% of the world population. A wide range of toxoplasmosis conditions has been studied, but there are still unknown damages which must be explored. In the present research, the effect of this parasite on testosterone and cortisol changes in the infected men and women was examined. Materials and methods: A total of 180 patients (73 females and 107 males), were examined for lgG anti-Toxoplasma antibody, cortisol and testosterone in their plasma. In addition, the patients also filled in personality questionnaire DASS21 (depression, anxiety, and stress). Results: Results showed that 24(%13/33) females and 39(%20) males were positive with lgG anti-Toxoplasma antibody, respectively. A statistically significant correlation between Toxoplasma infection and testosterone and cortisol increase in women and men were observed. Stress and anxiety index also increased in men and women whereas depression index increased only in men. Conclusion: The results show a direct relation between raise Toxoplasma infection and cortisol, and testosterone increase in bout men and women and high DASS21 test score in Toxoplasma infected group. Significance and impact of the study: Our results may indicate that following Toxoplasma infection, the probability of stressful condition is high.

Puppet Master: Possible Influence of the Parasite Toxoplasma Gondii on Managers and Employees

Abstract and Figures

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