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The scent of fear

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In this study we tried to find out if fear can be detected from human body odours. Female subjects wore under-arm axillary pads while watching a terrifying film. Saliva cortisol samples were taken before and after the film presentation as a hormonal measure for the fear response. The fear experience itself was measured by Spielberger's State-Trait Anxiety Inventory. A "neutral" film, shown one day after the "fear" film, was used as a control in a repeated measures design. In part two of the experiment, the axillary pads were presented to female subjects in a triple forced choice test. Results show that subjects were able to discriminate between fear and non-fear axillary pads, suggesting that women are indeed able to detect "the scent of fear". A direct correlation between induced fear, changes in cortisol levels and smell ratings could not be established. Thus cortisol levels are probably not the inducer of the scent of fear and a hypothetical fear pheromone could have other origins.
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79
Neuroendocrinology Letters ISSN 0172–780X
Copyright © 2002 Neuroendocrinology Letters
ORIGINAL RESEARCH REPORT
The Scent of Fear
Kerstin Ackerl, Michaela Atzmueller & Karl Grammer
Ludwig-Boltzmann-Institute for Urban Ethology at the Institute of Anthropology/University
of Vienna.
Correspondence to: Prof. Karl Grammer, Dr. Dipl. Biol.
Institute of Anthropology/University of Vienna
Althanstrasse 14
A-1090 Vienna / Austria.
EMAIL: karl.grammer@univie.ac.at
Submitted: April 2, 2002
Accepted: April 3, 2002
Key words: fear; human pheromones; cortisol; olfactory communication;
alarm substances
Neuroendocrinology Letters 2002; 23:7984 pii: NEL230202R01 Copyright © Neuroendocrinology Letters 2002
Abstract In this study we tried to fi nd out if fear can be detected from human body
odours.
Female subjects wore under-arm axillary pads while watching a terryfying
lm. Saliva cortisol samples were taken before and after the fi lm presentation
as a hormonal measure for the fear response. The fear experience itself was
measured by Spielberger’s State-Trait Anxiety Inventory. A “neutral” fi lm,
shown one day after the “fear” fi lm, was used as a control in a repeated mea-
sures design. In part two of the experiment, the axillary pads were presented
to female subjects in a triple forced choice test. Results show that subjects
were able to discriminate between fear and non-fear axillary pads, suggesting
that women are indeed able to detect “the scent of fear”. A direct correlation
between induced fear, changes in cortisol levels and smell ratings could not
be established. Thus cortisol levels are probably not the inducer of the scent
of fear and a hypothetical fear pheromone could have other origins.
People have always used scents to
either mask their body odour or to ex-
press and emphasize their moods or ap-
pearance. The possibility that odours
can also provide relevant biological in-
formation about their “sender” has
only in recent years become the focus of
scientifi c attention. Doty [1] described
the advantages of olfactory communi-
cation as follows: the sense of smell
even works if the other two major
senses (visual and acoustic) are func-
tionally restricted (for example if it
is too dark or too loud). Moreover,
odourous substances can easily be
spread over large areas and can last for
a long time. Intensity, distribution, and
quality of scent marks can give infor-
mation about size, reproductional and
nutritional status, etc. of an individ-
ual without immediately drawing un-
wanted attention to the sender (e.g. de-
tection from a predator via the loud
noise, etc. of a sender). Another advan-
tage in communication through odours
lies in the fact that sender and receiver
dont have to be in close spatial dis-
tance in order to communicate.
80
The question then becomes prominent: if olfactory
communication is useful in other animals, why is it not
used by human as well?
In recent years this assumption has undergone
major revision. Several studies indicate that humans
do indeed seem to use olfactory communication and are
even able to produce and perceive certain pheromones
(for a detailed overview see [2]). Up to now most stud-
ies were looking at human pheromones linked to the
sex hormones, the question of whether humans are or
are not able to communicate other than sex-related in-
formation through odours has yet to be raised.
Fear arises in stressful situations that are subjec-
tively perceived as threatening. The intensity of the
induced negative feeling corresponds to the subjective
perception of threat in a situation. If the negative feel-
ing becomes too intense, a seeking-reaction for stress-
relieving mechanisms is initiated [3].
Fear can be induced by external, objective threats (e.
g. predators), as well as by internal, subjective threats,
called free oating anxieties[4]. Free oating anxi-
eties can be generated by conscious or subconscious
memories of threatening experiences in the past, or by
the mere anticipation of a stressful situation.
The assumption that fear is a learned avoidance re-
action to potentially dangerous situations is gradually
being questioned. Recent studies show that fear may
be a genetically determined function of the nervous
system [4]. This hypothesis receives support from an
evolutionary point of view. The ability to detect and
anticipate dangerous situations seems to be crucial for
survival, and individual learning might not be entirely
quick enough to ensure survival chances. Moreover,
even potentially dangerous stimuli might be rare and
thus impossible to learn leading an individual into
danger when the stimulus is encountered for the rst
time.
Panksepp [4] describes a major fear circuit in the
brain located within the lateral and central parts of the
amygdala in the lobus temporalis, the periaquaeductal
grey (PAG) of the diencephalon and mesencephalon,
and as output-generating parts the brain stem and
the medulla.
Fear leads to reactions that are both behavioral
and physiological. Behavioral reactions include either a
freeze, “fl ight, or “fi ght response. Underlying phys-
iological processes include an increase in heart rate,
muscular tension, sweating, etc., and, most important,
a response of the adrenal gland via the pituitary-hy-
pothalamus-adrenal-axis (HHN) which leads to the
release of cortisol. The cortisol level rises as a con-
sequence of the production of corticotropin releasing
hormone and ACTH [5]. Thus in many experiments the
assessment of changes in cortisol levels is used as an
indicator of potentially experienced fear. In a study by
Hubert & de Jong-Meyer [6] male subjects showed an
increase in cortisol levels (measured from saliva) while
they were watching a horror lm. Kirschbaum & Hell-
hammer [7] found similar results. In contrast, Hubert,
Möller, & de Jong-Meyer [8] showed that subjects expe-
rienced an increase in cortisol levels in response to a
funny movie. The authors speculate that every kind of
affective arousal and change of mood, positive as well
as negative, could be linked to cortisol secretion.
Besides fear inducing situations, everyday stressors,
the so-called daily hassles, can also provoke a raise
in cortisol levels [9; 10]. In fact, it seems that the mere
anticipation of a stressful experience can have this ef-
fect [11].
It thus remains doubtful that cortisol secretions
might function solely as a result of experiencing fear.
Cortisol raises in such situations could also be due to
the stressing effects of fear.
Alarm pheromones were found in sh as early as
1941 by Von Frisch [12] and have since then been
found in many species. Today we know that at least in-
sects, annelids, and sh use olfactory signals to inform
their conspeci cs about stress, alarm, and fear. In ants,
for example, alarm substances can cause aggregation,
dispersion, or defense of the colony depending on the
senders status [13]. The use of alarm pheromones
has also been demonstrated in bees (Apis mellifera)
[14] and lice (Acyrthosiphon pisum) [15]. On defec-
tive stimulation earthworms (Lumbricus terrestris)
give off a substance that makes their conspeci cs avoid
their area and thus potential predators [16]. Among
vertebrates, sh are the best known example for the
use of alarm substances: fathead minnows (Pime-
phales promelas) that have never before been con-
fronted with a pike (Esox lucius) immediately know
that it is a dangerous predator because the pike seems
to get marked by an odour label by every minnow it
actually catches [17]. Sources of alarm substances in
minnows are for example urine, feces, and mucus.
Mammals also seem to use olfactory alarm signals.
Valenta & Rigby [18] were able to show that rats can
distinguish between the odour of stressed and re-
laxed conspeci cs. Carr, Martorano & Krames [19]
found that male mice prefer the smell of conspeci cs
that have just won a ght over the smell conspeci cs
that have not won a ght, and the smell of conspecif-
ics that havent been experimentally shocked, over the
smell of conspeci cs that have been treated with elec-
tric shocks.
In predator-prey-interactions between Mongolian
jirds (Meriones unguiculatus) and cats it was shown
that the stressed mice mark the dangerous areas
with their scent and thus tell their conspeci cs to avoid
these areas, while cats orientated themselves by the
scent of stressed mice in order to nd them [20].
If other mammals are able to warn their conspecif-
ics or at least send out the information that they
are in a frightening situation by emitting odourous
substances, the question becomes prominent: Do hu-
mans possess similar mechanisms? If so, how are these
Kerstin Ackerl, Michaela Atzmueller & Karl Grammer
81
Neuroendocrinology Letters ISSN 0172780X Copyright © 2002 Neuroendocrinology Letters
mechanisms related to cortisol release? The current
research aims to address these questions.
Methods
Collecting the odour samples
In the rst part of the experiment odour samples
for later assessment were gathered. In order to do so,
rectangular pads (6 x 10 x 1cm in size) of sterile cel-
lulose were treated with a solution of 40g Cetaceum in
800ml diethyl ether. Cetaceum was used because it is
odourless and is an ideal xans for absorbing odours.
The pads were then glued to eece material with pieces
of tin foil in between and stored in airtight, odourless
plastic bags.
Forty-two female test subjects, aged between 18 and
33 years (mean age: 23,39 S.D.= 3,55) watched a horror
lm (Candyman, © Tristar Pictures Inc., 1992) for
70 minutes and a neutral lm (Lokorama, © S. R.
Film & Video Filmproduktions Ges.m.b.H., 1990) on
2 consecutive days, each presented at the same time of
day. The neutral lm showed the view from a drivers
seat of a southern-bound train ride, originating in Vi-
enna. The duration was the same as the horror lm.
While watching the lms, participants wore the pads
under their armpits to gather the odour samples. Par-
ticipants had been told to avoid perfumes and deodor-
ants on the days of the experiment and to refrain
from smoking and eating odourous dishes. Just be-
fore the experiment participants washed their armpits
with odourless medical soap and put on cotton t-shirts
that had been washed with an odourless detergent and
stored in an airtight plastic bag.
Room temperature was kept constant (at 26° Cel-
sius) throughout the experiment. After the experi-
ment, the axillary pads were deep-frozen at 20 °C for
later assessment.
Before and after the lm presentations, partici-
pants lled out questionnaires and donated saliva
samples with salivettes (Fa. Sarstedt, Rommelsdorf/
Germany). The salivettes then were deep-frozen at
20° Celsius.
The questionnaire consisted of three parts: in the
rst part the women were asked if they had shaved
their armpits, if they were taking oral contraceptives,
their mean cycle length, day of the cycle, and if they
were on any medication. The second part of the ques-
tionnaire consisted of Spielbergers [3] State-Trait-
Anxiety Inventory (STAI). In the third part, partici-
pants were asked to rate the lm they had just been
watching on a 110 scale by the adjectives: a) boring,
b) frightening, c) suspenseful, and d) funny. The state
anxiety scores were later used to check if the actual
situation had evoked fear in the subjects; trait anxi-
ety scores were used to determine the subjects general
level of anxiety. The STAI scores range from a mini-
mum of 20 points to a maximum of 80 points.
Rating of the odour samples
In the second part of the experiment, the frozen
axillary pads containing the womens odour samples
from both lms were put in odourless plastic bottles,
which were then heated to 37 °C (human body temper-
ature). These bottles were presented to independent
female raters. Three pads per donor were presented
to 62 raters (aged 1872 years, mean age: 22,02; S.D.
=7,51). The combination of bottles for rating (two hor-
ror samples, one neutral sample and vice versa) was
chosen randomly. In a triple forced choice test the rat-
ers were asked to assess if there was a difference in the
smell of the three bottles. They were told to write down
their rst impression of each odour, even if there was
no consciously detectable smell. Then they had to rate
each bottle by a) intensity of smell, b) pleasantness c)
smells like sex, d) smells like aggression e) smells
like fear on 10 cm long analogue scales [21]. Finally
the raters had to ll in questionnaires concerning their
smoking habits, age, cycle day, cycle length, diseases of
the respiratory tract, etc.
Results
Fear
Analysis of State-Anxiety Scales (STAI) scores be-
fore and after the horror lm, shows that [t] partici-
pants actually experienced fear: the mean state anxi-
ety value before the horror lm is signi cantly lower
than after the movie (T-test for dependent variables:
n=41; t=5,18; df=40, p=0,000; Mean state value be-
fore horror lm: 33,71; sd=7,54; mean state value
after the lm: 42,33; sd=10,98). Effect size is a raise in
14,37 % of the possible range. See gure 1.
The Scent of Fear
Figure 1: State-Anxiety values (SA) before and after the
horror fi lm (T-test for dependent variables: n=41; t=-5,18;
df=40, p=0,000, Mean state value before horror fi lm: 33,71;
sd=7,54; mean state value after the fi lm: 42,33; sd=10,98).
4141
N=
SA
70
60
50
40
30
20
10
0
before horror movie
after horror movie
82
In the control situation, the neutral lm, no sig-
ni cant changes in the subjects anxiety scores before
and after the presentation could be found (T-test for de-
pendent variables: n=42; t=0, 176; df=41; n.s.; mean
state value before lm: 31,93; sd=5,81; mean state
value after lm: 32,10; sd=5,41).
When we compare the changes in the State-Anxiety
scores before and after the lm presentation across ex-
perimental conditions, we also nd a signi cant dif-
ference. The changes in state anxiety scores in the
horror situation are distinctly larger than in the con-
trol situation (T-test for dependent variables: n=41;
t=14,535; df=40; p=0,000; Mean difference horror:
8,73; sd=10,8; mean difference controls: 0,17; df=6,13).
Moreover, there are signi cant differences in the lm
assessment of the horror lm and the neutral lm. The
test subjects rated the horror lm as signi cantly less
boring (Wilcoxon; n=41; Z=5,579; p=0,000), signi -
cantly more frightening (Wilcoxon; n=41; Z=5,579;
p=0,000), signi cantly more suspenseful (Wilcoxon;
n=41; Z=5,579; p=0,000), and signi cantly less funny
(Wilcoxon; n=41; Z=2,398; p<0,02) than the neutral
lm. Thus we can conclude that the horror lm actually
induced fear in our subjects.
Cortisol
When we compare the subjects cortisol levels be-
fore and after each lm presentation, we nd that the
cortisol concentrations decrease signi cantly in both
the test (Wilcoxon; n=41; Z=3,920; p=0,000; mean
cortisol level before lm: 4,6; sd=3,28; after lm:
3,57; sd=2,54) and the control situation (Wilcoxon;
n=42; Z=5,370; p=0,000; mean level before lm:
4,96; sd=3,09; mean level after lm: 3,19; sd= 2,06).
A correlation analysis between the changes in cor-
tisol levels and the changes in state-anxiety scores
during the horror lm shows no signi cant results
(Spearman: n=41; r=0,176; p>0,05) and no signi -
cant correlations between state-anxiety scores and cor-
tisol levels after the horror lm could be found (Spear-
man: n=41; r=0,21; p>0,05).
At this point it has to be mentioned that the well-
known circadian rhythm in cortisol concentrations
[22] was also present in the ndings. A signi cant
decrease in cortisol concentrations occurred with the
daytime (see table 1). Closer examination of cortisol
changes during movie presentation reveals that the
mean decrease in cortisol differs signi cantly between
the horror and the control situation. During the pre-
Table 1: Correlations between daytime and cortisol levels (Spearman).
n Mw Sd r
s
p
Correlation between Cortisol 41 4,60 3,28 –,745 ,000
(ng/ml) at beginning of horror lm
and the beginning time of horror lm
Correlation between Cortisol 41 3,57 2,54 –,595 ,000
(ng/ml) at the end of horror lm and
end time of horror lm
Correlation between Cortisol 42 4,96 3,09 ,676 ,000
(ng/ml) at beginning of neutral lm
and beginning time of neutral lm
Correlation between Cortisol 42 3,19 2,06 ,652 ,000
(ng/ml) at end of neutral lm
and the end-time of neutral lm
Table 2: Differences in the qualitative assessment of the odour samples (U-test).
Film n Mw Sd MR Z p
no/strong odour horror 638 47,38 29,34 667,30 2,948 <,01
neutral 635 42,63 28,57 606,56
pleasantness horror 635 35,96 21,80 613,52 2,044 <,05
neutral 633 42,11 20,97 655,54
aggression horror 633 23,01 26,20 653,58 1,965 <,05
neutral 633 20,72 25,43 613,42
sex horror 635 21,06 24,73 636,35 ,181 >,05
neutral 633 21,39 24,39 632,64
fear horror 634 25,61 27,02 649,58 1,574 >,05
neutral 632 23,76 26,39 617,37
Kerstin Ackerl, Michaela Atzmueller & Karl Grammer
83
Neuroendocrinology Letters ISSN 0172780X Copyright © 2002 Neuroendocrinology Letters
sentation of the horror lm, the subjects cortisol levels
dropped signi cantly less than during the control lm
(Wilcoxon; n=41; Z=2,138; p<0,05; mean difference
horror lm: 1,03; sd=1,84; mean difference control:
1,76; sd=1,58).
Odour assessment experiment
In order to nd out if women were able to detect a
difference between the neutral smell and the fright-
ened smell of the pads, we used a triple forced choice
test. This setting implies that a right decision by
chance would happen with a probability of 33%. We
found that the odour assessments were signi cantly
more often correct than it could be expected by mere
chance probability (One-Sample T-test: n=41; t=3,305;
p=0,002; Mean=42,67; Sd=18,73).
Changes in participants cortisol levels during the
acquisition of the odour samples had no in uence on
odour assessment, as no signi cant correlations could
be found between changes in cortisol levels in both the
horror and the neutral lm situation and the percent-
age of correct decisions (Horror lm: n=20; r=0,132;
p>0,05; Neutral lm: n=21, r=0,148; p>0,05).
If we look at the qualitative rating of the odour sam-
ples, we nd signi cant differences between the assess-
ments of the horror and the neutral samples (see
table 2). We nd that the odour samples from the hor-
ror lm presentation were rated as signi cantly more
odourous (U-Test: n=635; Z= 2,948; p<0,01; MR hor-
ror lm= 667,3; MR neutral lm= 606, 56), and less
pleasant (U-Test: n= 633; Z= 2,044; p< 0,05; MR hor-
ror lm= 613,52; MR neutral lm= 655,54) than the
samples taken after the presentation of the neutral
video. Although there are no differences in the rat-
ings smells like fear (U-Test; n= 632; Z=1,574;
p>0,05; MR horror lm= 649,58; MR neutral lm=
617,37) and smells like sex (U-Test: n=633; Z=
0,181; p>0,05; MR horror lm=6363,35; MR neu-
tral lm=632,64) between the test situations, the
women rated the samples from the horror lm as more
aggressive, than the neutral ones (U-test: n=633;
Z=1,965; p<0,05; MR horror lm= 653,58; MR neu-
tral lm= 613,42).
Discussion
The rst question of interest in this study is if the
test subjects were really frightened by the test situa-
tion. The results of the STAI show that the subjects
experienced a signi cant increase in their state anxiety
levels in the test situation. We can therefore conclude
that the horror lm was indeed suitable to evoke fear
in the female subjects. This result is consistent with
the result of Hubert & de Jong-Meyer [23] who found
that [] unpleasant fi lm stimuli reliably induce nega-
tively valenced mood changes.
Moreover, the fear-evoking effect of the horror video
is reinforced by the results of the subjects lm as-
sessments, as they rated the horror movie as signi -
cantly less boring, more frightening, suspenseful and
less funny than the neutral lm.
Changes in cortisol levels have been used as an in-
dicator for the experience of fear in many studies. In
our experiment, saliva samples were drawn in an in-
terval of about 70 minutes, just before and after the
lm presentation. Contrary to our expectations, the
mean cortisol concentration exhibited a decline in both
the test and the control situation. This result becomes
clearer if we look at our signi cant negative correlation
between cortisol levels and daytime, a well-known and
often described connection (e.g. [22]). Hubert and de
Jong-Meyer [6] found similar results: in their study,
the subjects cortisol levels dropped continuously for
forty minutes after the start of the experiment and
then slowly raised again, but never again reached the
starting point, not even after 180 minutes. The authors
explain this result by the circadian rhythm of cortisol,
with highest levels in the morning and lowest ones in
the evening.
It is important to notice that in our experiment the
decline in cortisol levels was signi cantly less during
the presentation of the horror lm than during the
presentation of the neutral one. This result indicates
that the HHN axis was indeed stimulated by the horror
lm and thus worked against the natural decline of
cortisol with daytime. The search for a dedicated fear
pheromone seems to be promising the result that
there are no correlations between the amount of expe-
rienced fear and cortisol, nor between the ability to de-
tect fear and cortisol levels exclude a mere effect due to
cortisol alone.
In the second part of the experiment, the odour
assessments, we nd that the female subjects were
indeed able to differentiate between the odour sam-
ples from the horror lm and the neutral lm situa-
tion. The expected 33% of correct assessments by pure
chance were signi cantly exceeded in our experiment.
This nding can be interpreted as a strong hint that
humans could use olfactory signals to inform their en-
vironment about their internal state, in our case, fear.
In addition to this effect, we nd differences in the
qualitative assessments of the odour samples between
the test and the control situation. The women rated
the smell of the pads from the horror situation as sig-
ni cantly stronger and more unpleasant than the pads
from the neutral situation, and the odour reminded
them of aggression. This can be taken as another
hint that the odour we release in fearful situations is
indeed special. Additionally, Panksepp [4] assumes a
strong link between the fear- and the rage-circuits
of the brain, which could also lead us to the assumption
that the odour production that perhaps accompanies
such emotions could have a similar link.
A summary of the results of this study suggests
that humans are indeed able to smell their conspecif-
ics fear, and can tell a difference between fear and
The Scent of Fear
84
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non-fear from body odours. It seems likely that this
olfactory signal could be a pheromone, as it is hard
to think of other plausible biological explanations for
its production. But of course it has to be stated at this
point, that our experiment cannot prove the fear-pher-
omone hypothesis, as a pheromone per de nition
has to evoke a reaction in the receiver, either a change
in behaviour, or/and in physiology. This question could
only be answered by follow-up studies.
Kerstin Ackerl, Michaela Atzmueller & Karl Grammer
What we know at the moment, as many studies in
the last few years have pointed it out, is that the human
sense of smell has by far been underestimated in the
past and that humans like other animals- use olfac-
tory signals for the transmission of biologically relevant
information. Our ndings give yet another hint that
olfactory communication in humans is of great impor-
tance.
Article
Among various volatile organic compounds (VOCs) emitted from human skin, trans-2-nonenal, benzothiazole, hexyl salicylate, α-hexyl cinnamaldehyde, and isopropyl palmitate are key indicators associated with the degrees of aging. In our study, extraction and determination methods of human body odor are newly developed using headspace-in needle microextraction (HS-INME). The adsorbent was synthesized with graphene oxide:polyaniline/zinc nanorods/zeolitic imidazolate framework-8 (GO:PANI/ZNRs/ZIF−8). Then, a wire coated with the adsorbent was placed into the adsorption kit to be directly exposed to human skin as in vivo sampling and inserted into the needle so that it was able to be desorbed at the GC injector. The adsorption kit was made in-house with a 3D printer. For the in vitro method, the wire coated with the adsorbent was inserted into the needle and exposed to the headspace of the vial. When a cotton T-shirt containing body odor was transferred to a vial, the headspace of the vial was saturated with body odor VOCs. After volatile organic compounds were adsorbed in the dynamic mode, the needle was transferred to the injector for analysis of the volatile organic compounds by gas chromatography/mass spectrometry (GC/MS). The conditions of adsorbent fabrication and extraction for body odor compounds were optimized by response surface methodology (RSM). In conclusion, it was able to synthesize GO:PANI/ZNRs/ZIF−8 at the optimal condition and applicable to both in vivo and in vitro methods for body odor VOCs analysis.
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As hunter-gatherers, humans used their sense of smell to identify plants and animals, to find their way within a foraging area, or to distinguish each other by gender, age, kinship, or social dominance. Because women gathered while men hunted, the sexes evolved different sensitivities to plant and animal odors. They also ended up emitting different odors. Male odors served to intimidate rival males or assert dominance. With the rise of farming and sedentism, humans no longer needed their sense of smell to find elusive food sources or to orient themselves within a large area. Odors now came from a narrower range of plants and animals. Meanwhile, body odor was removed through bathing to facilitate interactions in enclosed spaces. This new phenotype became the template for the evolution of a new genotype: less sensitivity to odors of wild plants and animals, lower emissions of male odors, and a more negative response to them. Further change came with the development of fragrances to reodorize the body and the home. This new olfactory environment coevolved with the ability to represent odors in the mind, notably for storage in memory, for vicarious re-experiencing, or for sharing with other people through speech and writing.
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Mammalian body odour conveys cues about an individual’s emotional state that can be recognised by conspecifics. Thus far, little attention has been paid to interspecific odour communication of emotions, and no studies have examined whether humans are able to recognise animal emotions from body odour. Thus, the aim of the present study was to address this question. Body odour samples were collected from 16 two-year-old thoroughbred horses in fear and non-fear situations, respectively. The horse odour samples were then assessed by 73 human odour raters. We found that humans, as a group, were able to correctly assign whether horse odour samples were collected under a fear- or a non-fear condition, respectively. Furthermore, they perceived the body odour of horses collected under the fear condition as more intense, compared with the non-fear condition. An open question remains, which is whether humans could simply distinguish between little versus much sweat and between high intensity versus low intensity or were able to recognise horses’ fear and non-fear emotions. These results appear to fit the notion that the ability to recognise emotions in other species may present an advantage to both the sender and the receiver of emotional cues, particularly in the interaction between humans and domesticated animals. To conclude, the present results indicate that olfaction might contribute to the human recognition of horse emotions. However, these results should be addressed with caution in light of the study’s limitations and only viewed as exploratory for future studies.
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The recent coronavirus disease of 2019 (COVID-19) pandemic led to major lifestyle changes. The present study sought to assess factors associated with fear to seek dental care during COVID-19 pandemic in Saudi Arabia. This cross-sectional study was conducted during the COVID-19 outbreak in 2020. An online questionnaire was filled by a convenient sample of adult Saudi residents through mobile instant messaging application. The following measures were collected: sociodemographic characteristics, fear of COVID-19 using validated Fears of Illness and Virus Evaluation scale, fear to seek dental care, perceived health status, and COVID-19 experience. There were 826 participants involved in this study (541 females and 285 males, mean age: 38.8 ± 13.29 years). Fear to seek dental care was significantly higher among females, younger age groups, people who perceived poor general and oral health, and people who perceived high risk of contracting the virus in dental clinics. After controlling for confounders, fear to seek dental care was significantly higher among the age group of 35–44 years, those who perceived high and moderate risk of COVID-19 infection in dental clinics, and among participants who reported untreated dental conditions. Fear that Others Get Sick, Fear of the Impact on Social Life, and Behaviors Related to Illness and Virus Fears were significantly associated with high levels of fear to seek dental care. Within the study’s limitations, fear of COVID-19 negatively impacted the study population’s willingness to seek dental treatment. Factors such as age, perceived risk of COVID-19 infection in dental clinics, and untreated dental conditions were associated with fear to seek dental care.
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A recent body of research has emerged regarding the interactions between olfaction and other sensory channels to process social information. The current review examines the influence of body odors on face perception, a core component of human social cognition. First, we review studies reporting how body odors interact with the perception of invariant facial information (i.e., identity, sex, attractiveness, trustworthiness, and dominance). Although we mainly focus on the influence of body odors based on axillary odor, we also review findings about specific steroids present in axillary sweat (i.e., androstenone, androstenol, androstadienone, and estratetraenol). We next survey the literature showing body odor influences on the perception of transient face properties, notably in discussing the role of body odors in facilitating or hindering the perception of emotional facial expression, in relation to competing frameworks of emotions. Finally, we discuss the developmental origins of these olfaction-to-vision influences, as an emerging literature indicates that odor cues strongly influence face perception in infants. Body odors with a high social relevance such as the odor emanating from the mother have a widespread influence on various aspects of face perception in infancy, including categorization of faces among other objects, face scanning behavior, or facial expression perception. We conclude by suggesting that the weight of olfaction might be especially strong in infancy, shaping social perception, especially in slow-maturing senses such as vision, and that this early tutoring function of olfaction spans all developmental stages to disambiguate a complex social environment by conveying key information for social interactions until adulthood.
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Global infectious pandemics can affect the psychology and behavior of human beings. Several tools were developed to evaluate the psychological impact of such outbreaks. The present study aimed to examine the psychometric properties of the Arabic translated version of Fear of Illness and Virus Evaluation scale (FIVE). FIVE is a 35-item tool consisting of four subscales that measure Fears about Contamination and Illness, Fears about Social Distancing, Behaviors Related to Illness and Virus Fears and Impact of Illness and Virus Fears. The tool was translated into Arabic by using a forward–backward translation. The online questionnaire contained the following sections: demographics, FIVE, Fear of COVID-19 Scale (FCV-19S) and face validity questions. Non-probability convenient sampling technique was used to recruit participants via a mobile instant messaging application. Reliability, concurrent validity, face validity and factor analysis were examined. The data consisted of 509 adult participants who reside in Saudi Arabia. The internal consistency of the Arabic FIVE subscales was high (0.84–0.91) with strong concurrent validity indicated by positive correlations of FIVE subscales with FCV-19S. Factor analysis suggested slightly different factor structures (Fears of Getting Sick, Fears that Others Get Sick, Fears of the Impact on Social Life and Behaviors Related to Illness and Virus Fears). Our data showed a better fit using the proposed structures. The Arabic version of the FIVE showed robust validity and reliability qualities to assess fear of COVID-19 on Arabic adult population.
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Objective In our canine scent detection research involving a specific volatile organic compound (VOC) associated with human epileptic seizure, we began to suspect involvement of the primitive neural networks associated with production of a previously undescribed human alarm pheromone as the origin of our seizure scent. We hypothesized that if we presented fear-scented sweat to our canine seizure scent detection team, and they identified the fear scent as their seizure scent, then that would suggest that they are identical compounds. Methods Following consent and approval, sweat samples taken from volunteers associated with the Brooke Gordon Comprehensive Epilepsy Center at Denver Health were processed by the Canine Assistants (CA) service dog team that had been imprinted to recognize the unique seizure scent from our previous study. In part one, sweat samples were collected from subjects, who had no prior history of epilepsy or seizures, under two different testing environments: watching a scary movie (It) and a neutral/comedy movie (Airplane!). In part two, a larger follow-up study utilizing fear sweat, exercise sweat, epilepsy sweat, and other distractor scents were provided in a multiple choice paradigm to better understand the inter-rater reliability of the canine responses. Results In part one, our canine seizure scent detection team identified fear-scented sweat samples as their seizure scent in 4 of 5 study participants. There was almost perfect agreement of seizure scent detection during fear scent trials between the canine seizure scent detectors with a kappa value of 0.814 (95% CI: 0.668–0.960). In part two, (utilizing eleven different subjects) our canine scent detection team identified samples of either fear or seizure sweat with a sensitivity of 82% and a specificity of 100% (no false positives) from among the multiple choices offered. Additionally, there was 92% agreement between the members of the canine scent detection team. Significance While this hypothesis testing study is small and deserves replication, it confirms that the Canine Assistants seizure scent detection team consistently and accurately identified fear-scented sweat as their seizure scent, implying that the VOC, menthone, is common to both conditions. This further implies that human seizure propagation and fear network circuitry may share a common anatomy, and that menthone may not only be an early seizure biomarker, but a newly described human alarm pheromone.
Chapter
Emotionen und Erlebnisse sind subjektive Bestandteile jeder Veranstaltung und eine Herausforderung für EventplanerInnen. Erkenntnisse und Modelle der Neurowissenschaften können genutzt werden, um menschliche Wahrnehmungs- und Verarbeitungsprozesse besser zu verstehen und in der Planung für eine „gehirngerechte“ Neurokommunikation zu berücksichtigen. Eine kritische Betrachtung ordnet die Verbreitung der Vorsilbe Neuro- in den aktuellen Stand von Forschung und Praxis ein. Neben einem Grundverständnis für die strukturelle und funktionelle Perspektive der Neurowissenschaften, werden apparative Verfahren mit potenziellen Einsatzfeldern in der Eventforschung beleuchtet. Für ein ganzheitliches Verständnis werden zentrale Ansätze wie die Prospect Theory (Kahneman und Tversky), das hierarchische Emotionsmodell (Panksepp) und das Zürcher Modell der sozialen Motivation (Bischof) erläutert und eingeordnet. Für die Anwendung im Eventkontext werden die praxisorientierten Modelle Limbic® Map (Häusel), Vier-Code-Modell (Scheier und Held) und NeuroMap® (Morin und Renvoisé) reflektiert und synthetisiert. Anhand eines Anwendungsbeispiels werden die konkreten Einsatzmöglichkeiten der Erkenntnisse des Neuromarketings für die Eventplanung aufgezeigt.
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Article
en When exposed to predator cues, ostariophysan fishes exhibit short‐term anti‐predator behavioural responses in order to minimise predation risk. Non‐native predator cues are, however, likely to elicit poor behavioural responses in native prey fishes. This study investigated whether chubbyhead barb Enteromius anoplus , a native freshwater minnow in South Africa, had the innate ability to recognise and respond to largemouth bass Micropterus salmoides , a non‐native piscivore. This was experimentally evaluated by investigating behavioural responses to both the non‐native predator's odour and damage‐released conspecific alarm substance (CAS). Chubbyhead barbs did not exhibit any behavioural response to largemouth bass odour both before and after exposure to CAS. This suggests that the chubbyhead barbs likely lacked the innate ability to recognise the non‐native largemouth bass predator kairomones. By comparison, exposure to CAS was associated with significant behavioural responses, with chubbyhead barbs shifting from free‐swimming to hovering, and frequent use of refugia. This suggests that despite ineffective response to non‐native largemouth bass odour, chubbyhead barbs responded to general predator attack. Overall, this study suggests the potential for non‐native largemouth bass to induce negative consumptive effects on chubbyhead barbs due to their inability to identify non‐native predator's odour. In addition, nonconsumptive effects are likely due to altered activities in response to predator attack. Résumé fr Lorsqu'ils sont en présence de signaux de prédateurs, les poissons ostariophyses adoptent une réaction comportementale anti‐prédateurs à court terme afin de limiter les risques liés à ces derniers. Néanmoins, les signaux de prédateurs non indigènes sont susceptibles de susciter de faibles réactions comportementales de la part des espèces de poissons proies indigènes. Cette étude a pour objet de déterminer si le barbillon à tête ronde Enteromius anoplus , un méné d'eau douce présent en Afrique du Sud, a la capacité innée de reconnaître et de réagir face à la présence de l'achigan à grande bouche Micropterus salmoides , un piscivore non indigène. Ceci a été évalué de façon expérimentale en étudiant les réactions comportementales face à l'odeur des prédateurs non indigènes et la substance d'alerte conspécifique libérée par les atteintes. Le barbillon à tête ronde n'a manifesté aucune réaction comportementale face à l'odeur de l'achigan à grande bouche avant et après exposition à la substance d'alerte conspécifique. Cela suggère que le barbillon à tête ronde est susceptible de ne pas avoir la capacité innée à reconnaître les kairomones de prédateur de l'achigan à grande bouche non indigène. Par comparaison, l'exposition à la substance d'alerte conspécifique a été associée à d'importantes réactions comportementales. En effet, le barbillon à tête ronde qui nage habituellement de façon libre se met dans ce cas à faire du surplace et à utiliser fréquemment des refuges. Cela suggère qu'en dépit d'une réaction inefficace face à l'odeur de l'achigan à grande bouche, le barbillon à tête ronde réagit aux attaques général du prédateur. D'une manière générale, cette étude révèle le potentiel de l'achigan à grande bouche à provoquer des effets de consommation négatifs chez le barbillon à tête ronde à cause de l'incapacité de ces derniers à identifier l'odeur des prédateurs non indigènes. Par ailleurs, les effets non liés à la consommation sont probablement dus à une modification des activités en réaction aux attaques des prédateurs.
Article
The host suicide hypothesis1, which derives from inclusive fitness theory2, postulates that parasitized individuals in spatially aggregated populations consisting of close kin may actively enhance their probability of dying. The fitness cost associated with suicide becomes negligible when infection by a parasitoid causes the expected reproduction of the host to approach zero. But the host will benefit from suicide, if by its death (and that of its parasite) the level of subsequent parasitism in its kin is reduced relative to that in non-kin. Although conceptually appealing, host suicide has not yet been clearly demonstrated3. Here we report that pea aphid (Acyrthosiphon pisum) parasitized by the braconid wasp Aphidius ervi, exhibit apparent suicidal behaviour in response to both aphid alarm pheromone and approaching coccinellid (ladybird beetle) predators. We believe this to be the first convincing evidence in support of the host suicide hypothesis.
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Extensive chemocommunication occurs between individuals of different species. We examined the interaction between Mongolian gerbils (Meriones unguiculatus) and between domestic cats (Felis domestica). Experiments indicated that stressed gerbils produce blood odors that stimulate physiological arousal and cause conspecifics to avoid areas contaminated with these odors. Domestic cats preferred these same odors and differentially consumed food contaminated with these odors. Both reactions are ecologically important in the interaction between prey and predator.
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1. Ein im freien Gewsser oder im Aquarium durch Ftterung zutraulich gemachter Ellritzenschwarm zeigt eine Schreckreaktion, wenn ihm ein verletzter Artgenosse beigesellt wird. In typischen Fllen sieht man die Fische nach einer Latenzzeit von etwa 1/2 Min. zusammenschrecken, zu Boden gehen, sich eng aneinanderschlieen, und dann suchen sie nach kurzer Zeit das Weite oder fliehen (im Aquarium) ins Versteck. Es kann stunden- oder tagelang dauern, bis die alte Zutraulichkeit wiederkehrt. 2. Die Schreckreaktion wird durch einen Schreckstoff ausgelst, der aus der verletzten Haut der Ellritze frei wird. 3. Es spielt keine Rolle, ob die verletzte Ellritze lebend oder tot ist. Bei Fischen, die ohne Verwundung abgettet werden, geht einige Zeit nach Eintritt des Todes der Schreckstoff auch aus der unverletzten Haut in das Wasser ber. 4. Der Anblick einer leblosen Ellritze lst keine Schreckreaktion aus. 5. Empfindliche Schwrme reagieren noch deutlich auf einen Extrakt aus Eilritzenhaut (0,2 g Haut in 200 ccm Wasser extrahiert) bei einer Verdnnung von 1: 500. Es werden 100 ccm des verdnnten Extraktes eingegossen. Da er sich hierbei mit dem Wasser des Beckens mischt, ist der wahre Verdnnungsgrad, auf den die Fische eben noch ansprechen, erheblich grer. 6. Die Schwrme sind individuell verschieden empfindlich. Ein und derselbe Schwrm reagiert bei wiederholten Versuchen mit der gleichen Verdnnungsstufe oft durchaus gleichartig, er kann sich aber auch abstumpfen oder (seltener) mit zunehmender Empfindlichkeit ansprechen. 7. Man erhlt durchschnittlich bessere Reaktionen: in kleineren Becken, an lnger eingewhnten oder langsam zutraulich gewordenen Schwrmen. Ohne deutlichen Einflu auf die Reaktionsbereitschaft sind die Herkunft und das Alter der Fische, die den Schwrm zusammensetzen, und die Jahreszeit. 8. Auch der Schreckstoffgehalt der Haut zeigt bei Ellritzen verschiedener Herkunft, verschiedenen Alters oder verschiedenen Geschlechtes keine wesentlichen Unterschiede. 9. In einer mehrmonatlichen Hungerzeit sinkt der Schreckstoffgehalt der Ellritzenhaut auf etwa 1/4. 10. Es besteht kein nennenswerter Unterschied im Schreckstoffgehalt zwischen der dunklen Rckenhaut und der nur mit rotem Pigment und Guanin ausgestatteten Bauchhaut der Ellritze. 11. Im Darm und in der Leber der Ellritze lt sich kein Schreckstoff nachweisen. Die Ovarien sind etwa 100fach, die Muskeln 20fach, die Kiemenblttchen 5–10fach weniger wirksam als die Haut. Die relativ starke Wirksamkeit der Kiemenblttchen ist wohl auf ihren Epithelberzug zurckzufhren. 12. Nach Ausschaltung des Geruchsinnes reagieren die Ellritzen auch auf unverdnnten Ellritzenhautextrakt nicht mehr. Der Schreckstoff ist also ein Riechstoff. Kontrollversuche zeigen, da die Reaktionsbereitschaft an sich durch die Operation nicht leidet. 13. Die Haut toter Ellritzen behlt mehrere Tage ihre Wirksamkeit. 14. Nach den Untersuchungen R. Httels ber die chemische Natur des Schreckstoffes aus der Ellritzenhaut scheint es sich um purin- oder pterinhnliche Stoffe zu handeln. Da sie wasserlslich, aber nicht flchtig sind, liegt eine Substanz vor, die fr Fische ein Riechstoff ist, aber fr uns als solcher nicht in Frage kommt. 15. Es wurden die Hute von 41 Swasserfischarten auf ihre Wirksamkeit im Vergleich mit der Ellritzenhaut geprft. Die Ergebnisse sind in Tabelle 18 (S. 120) bersichtlich zusammengestellt. 18 Arten gehren in andere Familien als die Ellritze. Ihre Hute enthalten keine nennenswerten Mengen eines fr Ellritzen wirksamen Schreckstoffes (relativer Wirkungsgrad im Hchstfalle 1/100). Die Haut der Familienangehrigen (Cypriniden) war im allgemeinen wirksam, doch erreichen nur 2 von den 23 geprften Arten angenhert den Wirkungsgrad der Ellritzenhaut. Fr die starken Unterschiede im relativen Wirkungsgrad der Haut auch innerhalb der Familie der Cypriniden (vgl. Tabelle 18) sind neben dem Verwandtschaftsgrad offenbar noch andere Umstnde magebend. 16. Flubarsche (Fam. Percidae) zeigen keine Schreckreaktion, auch nicht auf die Haut (oder andere Krperteile) von Artgenossen. 17. Aitel, Bitterlinge und Rotfedern (Fam. Cyprinidae) zeigen eine deutliche Schreckreaktion auf den Hautextrakt von Artgenossen. 18. Ellritzen sprechen auf den Hautextrakt von ihresgleichen strker an als auf den Hautextrakt von Bitterlingen und Rotfedern. Da auch Bitterlinge und Rotfedern auf den Hautextrakt der Artgenossen am strksten reagieren, mu entweder der Schreckstoff bei verschiedenen Arten qualitativ verschieden oder neben dem Schreckstoff auch der charakteristische Artduft der Fische fr die Intensitt der Schreckreaktion mitbestimmend sein. 19. Nach anderweitigen Beobachtungen und Versuchen gibt es eine Schreckreaktion wahrscheinlich auch bei der Pltze, dem Grndling, der Laube, dem Schneider und der Orfe (durchwegs heimische Cypriniden) und sicher bei dem indischen Cypriniden Danio malabaricus. 20. Eine Schreckreaktion der geschilderten Art ist also bisher nur von gesellig lebenden Friedfischen bekannt. Ihre biologische Bedeutung liegt offenbar darin, da bei einem ruberischen berfall der aus der verletzten Haut eines gepackten Fisches frei werdende Schreckstoff die Kameraden warnt, 21. Es lt sich zeigen, da beim Verschlingen einer Ellritze durch einen Hecht tatschlich Warnstoffmengen frei werden, die hinreichen, um einen Ellritzenschwarm stark und nachhaltig zu verschrecken. 22. Die Reaktionsbereitschaft der Ellritzen wird in der Regel gesteigert, wenn sie nicht nur den Schreckstoff, sondern gleichzeitig einen Hecht geruchlich wahrnehmen. 23. Bei Freilandversuchen ist die Schreckwirkung auffllig an den Ort des Schreckerlebnisses gebunden. Whrend sich die Fische an dieser Stelle durch Futter nicht anlocken lassen, nehmen sie es einige Meter abseits ohne Scheu. 24. Aber auch dort ist ihr Gehaben nach einem Schreckerlebnis verndert. Sie sind von gesteigerter Wachsamkeit und reagieren mit Auge, Ohr und Nase auch auf unbedeutende Vernderungen, die sie vorher nicht beachtet haben. 25. Zweimal wurde eine Schreckreaktion unter natrlichen Bedingungen beobachtet: an einem Ellritzenschwarm, aus dem ein Barsch ein geschwchtes Tier herausholte, und an einem Laubenschwarm, aus dem eine Rohrdommel einen Fisch wegschnappte, der ihr wieder entkam. 26. Die Gewohnheit wehrloser Friedfische, sich zu Schwrmen zu vereinigen, wird nun besser verstndlich; denn bei einem ruberischen berfall kann bei geselligem Leben der Warnstoff fr die Allgemeinheit von Vorteil, ja von lebensrettender Bedeutung sein.
Article
Fathead minnows (Pimephales promelas) that have never encountered a predatory pike (Esox lucius), are able to detect conspecific alarm pheromone in a pike's diet if the pike has recently consumed minnows. It remains unclear how this minnow alarm pheromone is secreted by pike and if a pike is able to avoid being labelled as a potential predator by localizing these cues away from its foraging range. The first experiment determined that minnow alarm pheromone is present in pike feces when pike are fed minnows. Individual fathead minnows exhibited a fright response to a stimulus of pike feces if the pike had been fed minnows, but not if the pike had been fed swordtails, which lack alarm pheromone. Individual minnows also exhibited a fright reaction to alarm pheromone in the water (which contained no feces) housing pike which had been fed minnows, suggesting that alarm pheromone is also released in urine, mucous secretions and/or via respiration. The second experiment determined that test pike spent a significantly greater proportion of time in the home area of the test tanks (i.e. where they were fed) but the majority of feces were deposited in the opposite end of the test tank. By localizing their defecation away from the home or foraging area, pike may be able to counter the effects of being labelled as a predator by the alarm pheromone of the prey species.
Article
The assessment of cortisol in saliva has proven a valid and reliable reflection of the respective unbound hormone in blood. To date, assessment of cortisol in saliva is a widely accepted and frequently employed method in psychoneuroendocrinology. Due to several advantages over blood cortisol analyses (e.g., stress-free sampling, laboratory independence, lower costs) saliva cortisol assessment can be the method of choice in basic research and clinical environments. The determination of cortisol in saliva can facilitate stress studies including newborns and infants and replace blood sampling for diagnostic endocrine tests like the dexamethasone suppression test. The present paper provides an up-to-date overview of recent methodological developments, novel applications as well as a discussion of possible future applications of salivary cortisol determination.
Article
The present study, which aims to investigate effects of low and high trait anxiety on saliva cortisol secretion, was performed on 64 healthy male volunteers. They were assigned either to an unpleasant or a control film. Furthermore, subjects were divided within each film group by median split of their anxiety ratings into high and low trait anxious groups, resulting in four equal-sized groups. Saliva cortisol and mood ratings were the dependent variables. In contrast to the low anxious, the high anxious subjects responded with a diminished saliva cortisol response.