Saturday, April 25, 2020

The Genetic Inactivation of the Vomero-Nasal Organ in Primates Allows the Evolution of Same-Sex Sexual Behavior But Does Not Explain Homosexual Orientation in Humans

Camperio Ciani, A.S. The Genetic Inactivation of the Vomero-Nasal Organ in Primates Allows the Evolution of Same-Sex Sexual Behavior But Does Not Explain Homosexual Orientation in Humans. Arch Sex Behav, April 24 2020.

A variety of mammals, including primates, communicate
through pheromones, which are volatile chemical signals
produced by glands and detected through the vomero-nasal
organ (VNO). This manner of communication is effective
and fundamental for eliciting innate responses to locate
sexual partners and inducing sexual behavior. Pfau, Jordan,
and Breedlove, (2019) hypothesized that progressive
degeneration of a single-gene coding for pheromones receptors
in the VNO of mammals may have triggered a cascade
of functional and behavioral consequences that facilitated
the development of new modes of sexual communication,
including same-sex sexual behavior in primates and humans.
This hypothesis is compelling, testable, and heuristic.
In their Target Article, Pfau et al. (2019) suggest that, during
primate evolution, inactivation of the transient receptor
potential cation channel 2 (TRPC2) gene caused a shift from
strictly pheromonal-driven sexual behavior toward a more
flexible sexual response that allowed for occasional samesex
sexual behavior. In other words, a more flexible sexual
response to different and varied stimuli might have allowed
the use of sex, including same-sex sexual activity, in both
sexes, in contexts beyond reproduction such as dominance
displays, reconciliation, and appeasement (de Waal, 1989).
The main evidence in support of Pfau et al.’s (2019)
hypothesis comes from knock-out (KO) TRPC2 mice. Pfau
et al. found that this experimental strain of KO mice exhibits
delay development and altered intraspecific interactions such
as sex discrimination and male–male aggression (Leypold
et al., 2002; Stowers, Holy, Meister, Dulac, & Koentges,
2002). Most importantly, compared to wild mice strains,
adult male and female KO TRPC2 mice were observed to
engage in unprecedented levels of same-sex sexual behavior
including mounting and pelvic thrusting.
Comparing KO TRPC2 mice and Old World monkeys,
Pfau et al. (2019) furnish evidence that catarrhine primates,
which lack a VNO, also have a nonfunctional TRPC2 gene.
They argued that like KO TRPC2 mice, catarrhine primates
exhibit reduced aggressions and delayed development. Based
on these comparisons, they proposed that this TRPC2 single-
gene inactivation might explain not only the cause of
same-sex sexual behavior in nonhuman primates, but also the
cause of sexual orientation in humans. Further, they proposed
that the inactivation of the TRPC2 gene promoted a series
of behavioral and social transformation that are common in
domesticated animals and self-domesticated humans (Hare,
2017; Hare, Wobber, & Wrangham, 2012).
The primate data do not fit Pfau et al’s (2019) hypothesis
perfectly, however, and as the authors admit, there are some
prosimians (e.g., brown lemurs, Lemur fulvus, and sifakas,
Propitecus verreuxi; Bagemihl, 1999), as well as some New
World monkeys (e.g., common marmoset, Callitrix jacchus,
and Geoffroy’s tamarin, Saguinus geoffroyi) that have intact
TRPC2 genes and show same-sex sexual behavior (e.g.,
Manson, Perry, & Parish, 1997; Rothe, 1975). Conversely,
there are a number of Old World monkeys such as gibbons
and olive colobus (Procolobus verus) that lack a functional
TRPC2 gene, but have never been shown, in field observations,
to exhibit same-sex sexual behavior in either sexes.
However, these are minor exceptions, and in general Pfau
et al.’s hypothesis is supported by the primate data.
Pfau et al.’s (2019) hypothesis could also be tested in
other mammals known to have same-sex sexual behavior.
For example, dogs (Canis spp.) are known to have same-sex
sexual behavior both in females (Beach, Rogers, & LeBoeuf,
1968) and in males (Dagg, 1984), and at the same time they
are macrosmatic with a keen olfaction. Other possible animal
models include domesticated cattle and wild bison, since
same-sex sexual behavior has been extensively reported for
both (Jezierski, Koziorowski, Goszczyński, & Sieradzka,
1989; Lott, 1983). What about their vomero-nasal receptor
activity? Contrary to my expectation, dogs and cattle have a
markedly degenerated VNO, and most of the genes coding for
receptors in the VNO have completely degenerated and are
inactive, while their keen olfaction is due only to the primary
olfactory epithelium (Young & Trask, 2007). This evidence
from domestic mammals is, thus, consistent with the hypothesis
that a relation exists between vomero-nasal pheromone
receptor activity and same-sex sexual behavior. However,
there is evidence suggesting that in cattle the TRPC2 gene
is present and active contrary to Old World monkeys (Grus,
Shi, Zhang, & Zhang, 2005).
Research on the genes implicated in pheromone detection
and the evolution of the VNO of mammals (Moriya-Ito,
Hayakawa, Suzuki, Hagino-Yamagishi, & Nikaido, 2018)
suggests that there are a multitude of genes classified in two
super-families, which are expressed in the VNO, and some
of them in the main olfactory epithelium as well. Both the
vomero-nasal receptor genes type-1 (V1Rs) with single exon
and type-2 (V2Rs) with multiple exons are seven-transmembrane
G protein-coupled receptors (Nei, Niimura, & Nozawa,
2008). Both vomero-nasal receptor families have closely
related homologs in the vertebrate taste system: V1Rs are
closely related to T2R bitter taste receptors (Chandrashekar
et al., 2000), and V2Rs are closely related to T1R sweet and
umami taste receptors (Hoon et al., 1999).
Grus et al. (2005) found that these genes originated in
fishes, are extremely variable among mammals, and evolved
through duplication, deletion, and inactivation. Vomeronasal
receptor coding genes belong to the super-family of
genes with the highest numerical variability across species.
The proportion of intact V1Rs relates to multiple aspects of
VNO anatomy, including its relative size (Garrett & Steiper,
2014). The large variation of V1Rs in mammals may be an
adaptation to a broad range of environments, and the comparison
of V1Rs repertoires is critical for inferring the importance
of the VNO to each species (Garrett & Steiper, 2014).
Moriya-ito et al. (2018) reconstructed the phylogeny of
V1R genes in primates, almost all code for receptor proteins
that are present in the VNO. Moriya-ito et al. suggested
that, in general, V1Rs underwent positive selection, grew in
number, and are expressed in the VNO of prosimians. This
correlates with the socioecology of many prosimians, which
are nocturnal, solitary, and communicate extensively with
pheromones, including for mating (Dixson, 1995). It has been
also found that in Old and New World primates V1Rs show
a generalized trend toward degeneration (Grus et al., 2005;
Yoder & Larsen, 2014) and this regressive selection happened
not only in primates, but also in whales and bats (Grus
et al., 2005). Yoder and Larsen (2014) showed a reduction in
the number of intact V1Rs in anthropoids for which the VNO
was reduced or vestigial (Smith et al., 2002, 2011), which
suggested a correlation between the progressive inactivation
of V1Rs and reduction of the VNO. Young and Trask (2007)
also found that V2Rs families have completely degenerated in
humans, chimpanzees, macaques, cattle, and dogs. Each now
possesses 9–20 pseudogenes, but no intact V2Rs.
Rather than hypothesizing a single-gene inactivation as in
Pfau et al.’s (2019) Target Article, is it possible that general
regression of vomero-nasal functions is causally associated
with release from strict sexual response to pheromones and,
by extension, an increase in same-sex sexual behavior? It is
noteworthy that visual sexual signals, like the genital skin
swellings, are very widespread among Old World monkeys
and apes, but not in prosimians and New World monkeys
(Dixson, 1983). It has been proposed that sexual swelling
might visually signal receptivity in widely dispersed social
animals like chimpanzee, macaques, and baboons, but could
also be interpreted as evidence of the substitution of pheromone
signals with visual ones.
Now we come to my main concern with the argument forwarded
by Pfau et al. (2019): TRPC2 inactivation seems like
just one of the many genes involved in pheromone communication
in the VNO, which underwent regression partly in
New Word monkeys and completely in Old World monkeys,
as in other diurnal mammals. Why, then, suggest a specific
gene, TRPC2, as the driver of the whole behavioral transformation?
Instead, why not hypothesize that these behavioral
transformations resulted from the combined inactivation
and degeneration of a variety of genes involved in pheromone
detection and in the development and function of the
VNO. It could be argued, alternatively to Pfau et al.’s Target
Article, that the general regression of these genes allowed
the progressive shift from chemical communication toward
visual communication, including same-sex sexual behavior
as seems to have happen in New and Old World primates,
but also in sea mammals, bats, cattle, and dogs (Young &
Trask, 2007) .
The only evidence reported in Pfau et al.’s (2019) Target
Article against this more general hypothesis is that in
Gαi2 KO mice inactivation of this g-protein disrupts aggression,
but sexual behavior is not affected (Norlin, Gussing,
& Berghard, 2003). Disruption of Gαo, another g-protein
crucial for VNO function, also reduces aggression without
impacting sexual behavior (Chamero et al., 2011). Norlin
et al. (2003) reported unaltered sexual partner preference
in their Gαi2 KO mice, but Chamero et al. (2011) do not
report on any sexual behavior, so we do not know whether
any sexual changes occurred in their Gαo KO mice. Apart
from these cases, were KO mice ever produced for all other
V1Rs and V2Rs that are expressed in the VNO of mammals?
What modification in sexuality might such mice show?
Awaiting further evidence, my interpretation, at present, is
that circumstantial data best fit the more general hypothesis
for a global reduction of gene activity coding in the VNO.
We can imagine that, whenever chemical reception and communication
receded in favor of the visual communication,
selection pressures change. This might have begun when
ancestral primates invaded a diurnal niche, increased in social
complexity, developed trichromatic vision, and adopted the
use body signals (e.g., genital swelling), thereby eliciting
the evolution of sexual, rather than chemical, communication
signals (Moriya-Ito et al., 2018). Diurnal vision might
have enhanced brain size and reduced splanchno-cranial size
(Camperio Ciani, 1989), thus reinforcing reduction in VNO
size. Once sexual behavior was released from the limitation
of chemical activation, then sexuality could become much
more flexible and could be used by ancestral primates for
social communication in a variety of contexts. In extant primates,
same-sex sexual behavior might be used to modulate
aggression, reconcile conflicts, reinforce dominance rank,
and reduce social tension, thereby enriching social complexity.
The extreme example is the complex use of sexuality by
our closest relative the bonobo (Pan paniscus), in which sex
is used in the largest variety of social contexts, compared to
all other primates (Manson et al., 1997).
If my interpretation of the evidence is correct, no single
gene, such as TRPC2, but rather a whole set of genes (V1Rs,
and possibly V2Rs) lost importance. All those genes were
implicated, in one way or another, with pheromones detection
and communication in the VNO. When the VNO becomes
less important for sociosexual communication, its associated
genes become less useful and they experience more relaxed
selection pressure. The loss of selection pressure allows
for mutations to arise, such as stop codons, and generates
inactive pseudogenes (Moriya-ito et al., 2018). A relevant
exception pertains to those genes that shift function from
pheromones detection to oxygen detection. These genes are
maintained under stabilizing selective pressure, thus preserving
their functionality (Niimura, Matsui, & Touhara, 2014).
In sum, I would like to see stronger evidence that the loss of
a functional TRPC2 gene played an exclusive role in evolution
of same-sex sexuality, as opposed to a general evolutionary
transformation in mammals—not just primates—of
many vomero-nasal receptor genes, toward amplification or
A final critique of the Target Article, but one that is no less
relevant, is that Pfau et al.’s (2019) hypothesis does not apply
to human homosexuality. Most Old World primates have been
observed to engage in same-sex sexual behavior. Very occasionally
this involves some homosexual partner preference
(Vasey, 2002), but never exclusive homosexual orientation
as in humans. In humans, same-sex-sexual behavior lost its
social communication function almost completely to become
a sexual orientation.
I am skeptical that the olfactory and pheromonal processes
posited by Pfau et al. (2019) caused a homosexual “orientation”
in humans. The evolutionary dilemma of human
homosexual orientation has little to do with same-sex sexual
behavior, which is only one ingredient of the phenotype.
Homosexuality in humans is characterized by a novel and
specific phenotype: an individual exclusively attracted sexually
and romantically to same-sex individuals. This is the
evolutionary dilemma, exclusive same-sex sexual attraction,
which inhibits reproduction and reduces fertility. How could
such a phenotype evolve and how could it be maintained in
the population at a constant, albeit low, frequency? If this
phenotype has a genetic basis, then it should become extinct
rapidly, which we know does not happen (Camperio Ciani,
Battaglia, & Zanzotto, 2015). What are the fitness advantages
of exclusive same-sex sexual behavior in our species? Occasional
same-sex sexual behavior does not exclude heterosexual
sex and reproduction. On the contrary, it might provide a
selective benefit to individuals, in reducing aggressiveness
by using sexual pleasure to facilitate appeasement, but even if
this is true, it is generally not the case in humans. In animals,
same-sex sexual behavior enriches communication, sociality,
and ultimately benefits individuals, so there is no evolutionary
dilemma here. This is the ultimate reason that same-sex
sexual behavior evolved in many social organisms (Bagemihl,
1999). That said, these social uses of same-sex sexual behavior
do not produce exclusive homosexuality.
Pfau et al., in the Target Article, contend that the absence
of reports on possible homosexual orientation in primates,
including bonobos, might be ascribed to the possibility that
researchers not have detected it yet. They suggest that the
absence of evidence is not evidence of absence, but in this
case, it is improbable. Vasey (2002) reported facultative
(i.e., nonexclusive) homosexual preference for a few animals,
including the domestic rams and few other ungulates,
as well as female Japanese macaque (Macaca fuscata). These
females occasionally show a preference for same-sex sexual
partners over opposite-sex alternatives, but nevertheless they
mate heterosexually and they all reproduce, according to my
direct experience (Camperio Ciani, 1997; Corradino, 1990).
Moreover, most primatologist will acknowledge that primates
are difficult to locate in the wild, especially forest dwelling
ones; however, once located, sexual behavior becomes overt
(both visually and vocally) and very conspicuous in most
species, if not all. Sexual interactions in wild primates are
much easier to observe than in our species. Infinite hours of
observation, including in the wild, focusing on sexual behavior
in males and females have been undertaken by ethologists.
With such a large sample, it would have been easy to
locate individuals that engage in exclusive same-sex sexual
behavior, but no one has. I have been observing several species
of macaques in North Africa and South-East Asia and
commonly observe same-sex behavior among both females
and males, but never once have I observed a single-subject
mating exclusively with same-sex partners (Camperio Ciani
1986; Camperio Ciani, Mouna, & Arhou, 2000; Camperio
Ciani et al., 2005). There is only one species in which some
males exhibit a homosexual orientation, but this is in sheep,
not in primates, and is restricted to domesticated, that have
been artificially selected. Domestic rams can thus furnish
information on the neurophysiology and endocrinology of
homosexuality, but they cannot furnish information about
how natural selection might have produced such a phenotype
(Roselli, Larkin, Schrunk, & Stormshak, 2004).
Pfau et al. (2019) suggested that if homosexual individuals
occur in small groups, as might be the case for many
primates, there might be no possibility of finding a homosexual
partner with the same orientation. This, they suggest,
might help account for the lack of observations of exclusive
same-sex sexual partner preference in primates. This speculation
is untenable. First, many primates, including baboons,
macaques, and vervets, live in large multi-male multi-female
groups. If occasional same-sex behavior is already present
within a species—as is the case for many primates—an exclusively
homosexual individual, should one exist, could find
several same-sex partners with whom they could engage in
sex, even if those partners were not exclusively homosexual
themselves. This in fact happens also in our own species,
where exclusive homosexual individuals can find occasional
partners who are heterosexual (Whitam, 1992).
In conclusion, the hypothesis that the decline of pheromonal
communication allowed for the evolution of social
complexity, including same-sex sexuality, is compelling. In
my view, the idea that a single gene, and not a whole set of
genes, promoted this shift needs further testing. Regardless,
Pfau et al.’s (2019) hypothesis while heuristic for the evolution
of same-sex sexuality in nonhuman primates, fall short
of explaining the evolution of an exclusively homosexual
phenotype as seen in humans.

Trump Depression: Liberals report being more depressed when asked directly about the effects of the 2016 election; however, more indirect measures show a short-lived or non-existent effect

Simchon, Almog, Sharath Guntuku, Rotem Simhon, Lyle H. Ungar, Ran Hassin, and michael gilead. 2020. “Political Depression? A Big-data, Multi-method Investigation of Americans’ Emotional Response to the Trump Presidency.” PsyArXiv. April 21. doi:10.1037/xge0000767

Abstract: Can a political loss in a participatory democracy lead to psychopathology? While some studies provide support for pathological levels of election-related distress in Liberal Americans, it has also been suggested that the public and professional discourse has increasingly over-generalized concepts of trauma and psychopathology. Here, we examine this debate in the context of the 2016 US presidential election, and investigate whether Liberal (vs. Conservative) Americans exhibited increased levels of depression in response to the Trump presidency. We observe that Liberals report being more depressed when asked directly about the effects of the election; however, more indirect measures show a short-lived or non-existent effect. We examined self-report measures of clinical depression with and without a reference to the election (Studies 1A & 1B), analyzed Twitter discourse and measured users’ levels of depression using a machine-learning-based model (Study 2), conducted time-series analysis of depression-related search behavior on Google (Study 3), examined the proportion of antidepressants consumption in Medicaid (Study 4), and analyzed daily survey data of hundreds of thousands of Americans (Study 5)—and saw that at the aggregate level, empirical data reject the accounts of “Trump Depression”. We discuss possible interpretations for the discrepancies between the direct and indirect measures. The current investigation demonstrates how big-data sources can provide an unprecedented view of the psychological consequences of political events, and sheds light on the complex relation between the political and the personal spheres.

Exposure to research on the genetic and biological etiology of political attitudes influences warmth toward partisan outgroups and preferences over political compromise

Severson, Alexander. 2020. “Homo Politicus Was Born This Way: How Understanding the Biology of Political Belief Promotes Depolarization.” SocArXiv. April 25. doi:10.31235/

Abstract: Most individuals perceive ideological beliefs as being freely chosen. Recent research in genopolitics and neuroscience, however, suggests that this conviction is partially unwarranted given that biological and genetic factors explain more variance in political attitudes than choice and environmental factors. Thus, it is worth exploring whether exposure to this research on the biological and genetic basis of political attitudes might influence levels of affective polarization because such exposure might reduce the perceived moral culpability of partisan outgroups for the endorsement of oppositional beliefs. In this paper, I employ an online survey experiment on Amazon Mechanical Turk (N = 487) to assess whether exposure to research on the genetic and biological etiology of political attitudes influences warmth toward partisan outgroups and preferences over political compromise. I present evidence that nontrivial numbers of participants in the treatment group reject the underlying science and do not update their genetic trait attributions for political attitudes. However, I also find that when the treatment is successful at increasing biological and genetic trait attributions, exposure to this research depolarizes strong-identifying partisans. Moreover, as partisans increasingly endorse biological and genetic trait attributions for political attitudes, they increasingly hold favorable attitudes toward political outgroups. These patterns suggest a potentially profitable inroad for political polarization interventions going forward.

People who are intellectually humble display less hostility towards conflicting viewpoints, which should induce less polarization, but can polarize strongly against what is perceived as arrogant, close minded individuals

Nadelhoffer, Thomas, Gus Skorburg, Rose Graves, Mark R. Leary, and Walter Sinnott-Armstrong. 2020. “Partisanship, Humility, and Polarization.” OSF Preprints. April 19. doi:10.31219/

Abstract: Much of the literature from political psychology has focused on the negative traits that are positively associated with affective polarization—e.g., animus, arrogance, distrust, hostility, and outrage. Not as much attention has been focused on the positive traits that might be negatively associated with polarization. For instance, given that people who are intellectually humble display greater openness and less hostility towards conflicting viewpoints (Krumrei-Mancuso & Rouse, 2016; Hopkin et al., 2014; Porter & Schumann, 2018), one might reasonably expect them to be less polarized. We ran two studies designed to explore the relationship between various forms of humility and polarization. Our chief finding is that people who value humility are prone to what we are calling epistemic polarization—that is, judging the epistemic traits of contrapartisans negatively—which in turn plays a role in polarization more generally. Not only are contrapartisans deemed to have the wrong moral and political beliefs, they are also viewed as less humble and more arrogant, close-minded, and irrational. This makes matters even worse when it comes to the growing partisan divide. In light of our findings, we believe that the novel concept of epistemic polarization that we introduce is a promising target for further investigation.

There are consistent patterns that could be considered a non-verbal signal of guilt in humans: Guilt was most closely associated with frowning and neck touching

Are there non-verbal signals of guilt? Eglantine Julle-Danière, Jamie Whitehouse, Alexander Mielke, Aldert Vrij, Erik Gustafsson, Jérôme Micheletta, Bridget M. Waller. PLoS, April 24, 2020.

Abstract: Guilt is a complex emotion with a potentially important social function of stimulating cooperative behaviours towards and from others, but whether the feeling of guilt is associated with a recognisable pattern of nonverbal behaviour is unknown. We examined the production and perception of guilt in two different studies, with a total of 238 participants with various places of origin. Guilt was induced experimentally, eliciting patterns of movement that were associated with both the participants’ self-reported feelings of guilt and judges’ impressions of their guilt. Guilt was most closely associated with frowning and neck touching. While there were differences between self-reported guilt and perception of guilt the findings suggest that there are consistent patterns that could be considered a non-verbal signal of guilt in humans.


This study aimed to identify which facial movements were perceived as guilt when guilt was induced in a laboratory experiment. We found that judges gave a higher rating of guilt in videos where people were seen frowning (AU4 Brow Lowerer) and touching their neck (Neck Touching). We used instances when judges reported seeing guilt to create 1s-window of interest and conduct our analysis only on those time windows of guilt. Doing this, we identified facial movements reliably associated with the perceived expression of guilty. Judges reported other emotions at the same time as guilt in only 14% of the guilt pinpoints. Moreover, pinpoints of guilt revealed specific facial movements that were not present in control videos. This made us fairly confident that the facial expressions identified were associated with the experience (perception) of guilt.

General discussion

In two studies, we aimed to identify facial movements and behavioural displays associated with the experience of guilt in humans. In the first study, we examined the production of guilt using a novel induction technique. In the second study, we examined whether others perceived guilt from the face of those experiencing guilt. We used an extensive, bottom-up coding scheme to identify facial patterns associated with the experience (production and perception) of guilt as part of a dynamic sequence of behaviour, combined with a robust bootstrapping method to analyse our data.
We found a positive relationship between the level of self-reported guilt and the extent this individual was judged as feeling guilty by others. This supports the idea that guilt could have evolved as an observable phenomenon with a potential communicative social function. The patterns identified in this experiment showed some consistency between what people do when feeling guilty and what people see when identifying guilt. Our first study showed that guilt was associated with frowning, lip stretching and neck touching [AU4 Brow Lowerer, AU20 Lips Stretch; 59], as well as looking towards the right (AU52 Head Right, AU62 Eyes Right), which was probably an artefact of the position of the computer. Our second study showed that the identification of guilt in others was associated with frowning, eyes widening, and neck touching [AU4 Brow Lowerer, AU5 Upper Lid Raiser, AU10 Upper Lip Raiser; 59], as well as looking down and sideways (AU54 Head Down, AU61 Eyes Left, AU62 Eyes Right, AU64 Eyes Down), another potential artefact due to the experimental set-up. Thus, it seems that in this study, guilt was associated with a non-verbal pattern of frowning and neck touching.
Using a bottom-up methodology allowed us not only to approach our question without any a priori assumptions regarding the results, but it also increased the likelihood that the movements identified in our studies (AU4, AU20, and neck touch) are associated with the experience of guilt and no other secondary moral emotion. Indeed, the “guilt” pinpoints identified by the judges (Study 2) were mainly instances of identification of guilt alone, with only 14% of the total number of guilt pinpoints associated with more than one emotion (see S1 Study of Table 2). This allowed us to focus our analysis on facial movements associated with the experience of guilt only. Moreover, even though guilt is often mistaken for embarrassment or shame, the embarrassed display has been characterised by the joint production of gaze down, controlled smiles, head turns, gaze shifts, face touches [44], and the occasional blushing [90]; and the typical face of shame was described with head and gaze movements down [4345]. None of the movements we found associated with the expression of guilt were associated with those of other negative self-conscious emotions. During the AU selection process, most facial movements associated with either embarrassment or shame were discarded from further analysis, with the only exception of face touching. Face touch can emphasise embarrassment displays, but it is not necessary for the identification of embarrassment [44]. A previous study suggested a link between blushing and admission of guilt [91]; combining FACS analysis with thermal imaging techniques might have revealed changes in facial temperature in guilty participants, which could be unconsciously used by observers in their judgments.
This bottom-up methodology also diverges from previous research examining the facial display of guilt, which is why we may have found a more concrete candidate for the display of guilt. One notable previous study used a literature-based conceptualisation of the experience of guilt to present three candidates’ displays to their participants [8]. In that study, using a top-down approach, the participants were presented with displays selected based on previous literature, which associated the experience of guilt with the experience of self-contempt, sympathy, and pain. The authors tested whether their conceptualisation of guilt accurately described a facial display associated with the experience of the emotion. The results were not conclusive as the candidates’ displays were more often associated with emotions other than guilt [8]. A more recent study associated the experience of guilty feeling with increased skin conductance and gaze avoidance [92]. We did not find gaze avoidance (i.e. actively avoiding to look in another person’s direction) to be part of the facial signal of guilt, even though participants in the guilt condition looked down and around more than participants in the control condition. Yet, this could be due to our experimental design: participants in the guilt condition might have been looking down at the laptop more than people in the control condition. It is thus unclear in our design whether guilty participants avoided eye-contact or focused on an object associated to their wrongdoing (the laptop could be incriminated for the deletion of data on the USB stick, removing the fault from them).
Both the production and perception of guilt was associated with self-directed behaviour (i.e., scratching, neck or face touching), which are often classified as displacement behaviours, and are defined as a group of behaviours that appear irrelevant to the situation in which they are displayed, but can gain communicative value over time [61]. The production of such behaviours has been shown to increase in stressful, negative, situations [93,94]. Self-directed behaviours may be used when individuals try to distance and protect themselves from an unpleasant situation, acting as a short-term diversion of attention, which could, in turn, reduce the negative feeling associated to the situation at hand [93,95,96]. Self-directed behaviour could thus help regulate the level of stress associated with emotionally challenging situations [94], such as the guilt induction experienced by our participants in Study 1. Indeed, some studies have shown that self-directed behaviours are common in situations such as embarrassment [44], discomfort [20], and anxiety and guilt [97], which focussed on hand movements and found a correlation between the production of self-directed behaviours (i.e., scratching) and anxiety and guilt feelings. In our study, we found that the experience of guilt was associated with self-directed behaviours (neck touching), which appears to be in line with previous research. However, the production of self-directed behaviours could be due to the experimental design: participants were seated at a table, in front of a computer. However, the setup is unlikely to have elicited those movements, as participants in the control condition, also seated at a computer, did not display as many self-directed behaviours.
More recent conceptualisations of emotional experiences [27,28,3537] argue for a less universal and omnipotent link between the experience of an emotion and behavioural outcomes. In an emotional context, multiple systems will be triggered (e.g., cognitive processes, physiological systems, motor expressions; [35]), leading to multiple behavioural outcomes (e.g. facial signals), one of which might be used by observers when responding to the situation [35]. As such, an individual feeling guilty might produce multiple facial signals, one of which will be more strongly associated with the subjective, constructed, feeling of guilt (e.g., frown, lips stretch and neck touching); an observer might perceive those facial signals and rely mainly on specific ones to interpret the emotional state of the guilty individual (e.g., frown and neck touching).
It is important to remain cautious in the interpretation of our data. We need to acknowledge that if neck touching was present more in association with feelings of guilt, only 12.5%of the individuals displayed neck touching. Self-directed behaviour, however, were displayed in over 64% of the individuals during the guilt induction. Even though few participants displayed neck touching, our results showed it is a significant signal of guilt. We need to consider the possibility that by reducing our dataset to 1-second windows, we could have excluded non-verbal signals important for the onset of the experience of guilt. By focussing on the apexes of the expressions, we might have lost secondary signals contributing to the reliable identification of guilty signals. Our results provide preliminary information regarding the non-verbal signals exhibited more in association with guilty feelings. A follow-up study, using a reduced ethogram focussing on the movements identified here could allow to reach a better agreement score between coders and thus increase the K’s alpha and the validity of our results [67,68]. We also need to consider the fact that providing contextual information might have influenced the judges in their decisions. To assess the impact of context, we conducted a follow-up study comparing the judgements made with and without contextual information provided [98]. Our judgement study also presents some linguistic limitations. Even if there are differences in the appraisal and behavioural outcomes between shame and guilt, it has been previously shown that English speaker use “guilt” and “shame” interchangeably [99]. To overcome this conceptual barrier, we conducted another judgement study, without providing contextual information [98,100]. We hope to gauge how the expression of guilt is perceived when no verbal/written content needs to be understood first. Moreover, to compare various judgement methodologies [emotion words vs action tendencies vs dimensions; 101], we conducted another follow-up study to help us have a better understanding of how people conceptualise the facial expression produced when experiencing guilt, using different types of words and classification methodologies [forced choice vs free labelling vs dimensions; 100]. This way, we hoped to introduce more variability in the emotional judgements, looking at patterns of mislabelling of guilty displays.
These are the first studies to look at the genuine expression of guilt and the perception of secondary emotion using spontaneous dynamic stimuli. Judges had to rely on genuine, dynamically presented facial expressions to recognise and rate emotions. They were exploratory studies, using simple analysis and focussing on the behavioural signals associated with a guilt-inducing situation. We have however collected more extensive data; now that we identified a facial signal associated with the experience of guilt, more in-depth analysis (such as a lens modelling [35]) would be an interesting step to further break down the mechanisms associated with guilt.
Our experiments support a drive towards a new scientific culture, studying facial expressions using novel approaches removed from the dichotomous debate about nature vs nurture [73,102]. Previous research extensively looked at the behavioural consequences of guilty feelings: it can promote directed action towards those who have been wronged [4], it can reduce prejudice behaviours [13] and increase generosity [6]. We focussed on the first reactions people have when realising they did something wrong and the guilty feelings emerge; we were able to identify reliable candidates characterising the experience of self-reported guilt. Building on this, we conducted a study to investigate guilty people’s propensity to repair the relationship, as well as the impact of a facial expression on the person wronged, i.e. the victim, reaction [103]. Together, our results suggest that guilt is expressed on the face and communicates the experience of guilt to others through a signal.

Is Discrimination Widespread? Testing Assumptions About Bias on a University Campus

Campbell, Mitchell R., and Brauer G. Lab. 2020. “Is Discrimination Widespread? Testing Assumptions About Bias on a University Campus.” PsyArXiv. April 21. doi:10.31234/

Abstract: Discrimination has persisted in our society despite steady improvements in explicit attitudes toward marginalized social groups. The most common explanation for this apparent paradox is that due to implicit biases, most individuals behave in slightly discriminatory ways outside of their own awareness (the dispersed discrimination account). Another explanation holds that a numerical minority of individuals who are moderately or highly biased are responsible for most observed discriminatory behaviors (the concentrated discrimination account). We tested these two accounts against each other in a series of studies at a large, public university (total N = 16,600). In four large-scale surveys, students from marginalized groups reported that they generally felt welcome and respected on campus (albeit less so than non-marginalized students) and that a numerical minority of their peers (around 20%) engage in subtle or explicit forms of discrimination. In five field experiments with eight different samples, we manipulated the social group membership of trained confederates and measured the behaviors of naïve bystanders. The results showed that between 5 and 20% of the participants treated the confederates belonging to marginalized groups more negatively than non-marginalized confederates. Our findings are inconsistent with the dispersed discrimination account but support the concentrated discrimination account. The Pareto principle states that, for many events, roughly 80% of the effects come from 20% of the causes. Our results suggest that the Pareto principle also applies to discrimination, at least at the large, public university where the studies were conducted. We discuss implications for pro-diversity initiatives. This paper has not been published.

During the pandemic, participants reported conforming more strongly to traditional gender roles and believing more strongly in traditional gender stereotypes than they did before

Rosenfeld, Daniel L., and A. J. Tomiyama. 2020. “Can a Pandemic Make People More Socially Conservative? Longitudinal Evidence from COVID-19.” PsyArXiv. April 22. doi:10.31234/

Abstract: The first months of 2020 threw people into a period of societal turmoil and pathogen threat with the novel coronavirus (COVID-19) pandemic. By promoting epistemic and existential motivational processes and activating people’s behavioral immune systems, this pandemic may have changed social and political attitudes. The current research specifically asked the following question: As COVID-19 became pronounced in the United States during March-April 2020, did people living there become more socially conservative? We present a longitudinal study (N = 695) that assessed political ideology, gender role conformity, and gender stereotypes among U.S. adults before (two months preceding) versus during the pandemic. During the pandemic, participants reported conforming more strongly to traditional gender roles and believing more strongly in traditional gender stereotypes than they did before the pandemic. Political ideology remained constant from before to during the pandemic. These findings suggest that a pandemic may promote preference for traditional gender roles.

Curiosity might correspond to an appetitive drive elicited by the state of uncertainty, because we like that state, or rather it might correspond to an aversive drive to reduce the state of uncertainty

van Lieshout, Lieke, Floris de Lange, and Roshan Cools. 2020. “Curiosity: An Appetitive or an Aversive Drive?” PsyArXiv. April 21. doi:10.31234/

Abstract: You probably know what kind of things you are curious about, but can you also explain what it feels like to be curious? Previous studies have demonstrated that we are particularly curious when uncertainty is high and when information provides us with a substantial update of what we know. It is unclear, however, whether this drive to seek information (curiosity) is appetitive or aversive. Curiosity might correspond to an appetitive drive elicited by the state of uncertainty, because we like that state, or rather it might correspond to an aversive drive to reduce the state of uncertainty, because we don’t like it. To investigate this, we obtained both subjective valence (happiness) and curiosity ratings from subjects who performed a lottery task that elicits uncertainty-dependent curiosity. We replicated a strong main effect of outcome uncertainty on curiosity: Curiosity increased with increasing outcome uncertainty, irrespective of whether the outcome represented a monetary gain or loss. By contrast, happiness decreased with higher outcome uncertainty. This indicates that people were more curious, but less happy about lotteries with higher outcome uncertainty. These results demonstrate that curiosity reflects an aversive drive to reduce the unpleasant state of uncertainty.

A Bayesian Multiverse Analysis of Many Labs 4: Quantifying the Evidence Against Mortality Salience

Haaf, Julia M., Suzanne Hoogeveen, Sophie Berkhout, Quentin F. Gronau, and Eric-Jan Wagenmakers. 2020. “A Bayesian Multiverse Analysis of Many Labs 4: Quantifying the Evidence Against Mortality Salience.” PsyArXiv. April 14. doi:10.31234/

Abstract: Many Labs projects have become the gold standard for assessing the replicability of key findings in psychological science. The Many Labs 4 project recently failed to replicate the mortality salience effect where being reminded of one’s own death strengthens the own cultural identity. Here, we provide a Bayesian reanalysis of Many Labs 4 using meta-analytic and hierarchical modeling approaches and model comparison with Bayes factors. In a multiverse analysis we assess the robustness of the results with varying data inclusion criteria and prior settings. Bayesian model comparison results largely converge to a common conclusion: We find evidence against a mortality salience effect across the majority of our analyses. Even when ignoring the Bayesian model comparison results we estimate overall effect sizes so small (between d = 0.03 and d = 0.18) that it renders the entire field of mortality salience studies as uninformative.