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The scent of fear

May 2002
Neuro Endocrinology Letters 23(2):79-84

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University of Vienna

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.

: Differences in the qualitative assessment of the odour samples (U-test).

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Neuroendocrinology Letters ISSN 0172–780X

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

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

ﬁ 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

don’t have to be in close spatial dis-

tance in order to communicate.

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 ﬂ oating anxieties”[4]. Free ﬂ 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 ﬁ 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 ﬁ 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 ﬁ 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 ﬁ sh use olfactory signals to inform

their conspeciﬁ cs about stress, alarm, and fear. In ants,

for example, alarm substances can cause aggregation,

dispersion, or defense of the colony depending on the

sender’s 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 conspeciﬁ cs avoid

their area and thus potential predators [16]. Among

vertebrates, ﬁ 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” conspeciﬁ cs. Carr, Martorano & Krames [19]

found that male mice prefer the smell of conspeciﬁ cs

that have just won a ﬁ ght over the smell conspeciﬁ cs

that have not won a ﬁ ght, and the smell of conspecif-

ics that haven’t been experimentally shocked, over the

smell of conspeciﬁ 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 conspeciﬁ cs to avoid

these areas, while cats orientated themselves by the

scent of stressed mice in order to ﬁ 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

mechanisms related to cortisol release? The current

research aims to address these questions.

Methods

Collecting the odour samples

In the ﬁ 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 ﬁ xans for absorbing odours.

The pads were then glued to ﬂ 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

ﬁ lm (“Candyman”, © Tristar Pictures Inc., 1992) for

70 minutes and a “neutral” ﬁ 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 ﬁ lm showed the view from a driver’s

seat of a southern-bound train ride, originating in Vi-

enna. The duration was the same as the horror ﬁ lm.

While watching the ﬁ 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 ﬁ lm presentations, partici-

pants ﬁ 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

ﬁ 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 Spielberger’s [3] State-Trait-

Anxiety Inventory (STAI). In the third part, partici-

pants were asked to rate the ﬁ lm they had just been

watching on a 1–10 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 women’s odour samples

from both ﬁ 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 18–72 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 ﬁ 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 ﬁ 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 ﬁ lm, shows that [t] partici-

pants actually experienced fear: the mean state anxi-

ety value before the horror ﬁ lm is signiﬁ 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 ﬁ lm: 33,71; sd=7,54; mean state value

after the ﬁ lm: 42,33; sd=10,98). Effect size is a raise in

14,37 % of the possible range. See ﬁ 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

before horror movie

after horror movie

In the control situation, the “neutral” ﬁ lm, no sig-

niﬁ 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 ﬁ lm: 31,93; sd=5,81; mean state

value after ﬁ lm: 32,10; sd=5,41).

When we compare the changes in the State-Anxiety

scores before and after the ﬁ lm presentation across ex-

perimental conditions, we also ﬁ nd a signiﬁ 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 signiﬁ cant differences in the ﬁ lm

assessment of the horror ﬁ lm and the neutral ﬁ lm. The

test subjects rated the horror ﬁ lm as signiﬁ cantly less

boring (Wilcoxon; n=41; Z=–5,579; p=0,000), signiﬁ -

cantly more frightening (Wilcoxon; n=41; Z=–5,579;

p=0,000), signiﬁ cantly more suspenseful (Wilcoxon;

n=41; Z=–5,579; p=0,000), and signiﬁ cantly less funny

(Wilcoxon; n=41; Z=–2,398; p<0,02) than the neutral

ﬁ lm. Thus we can conclude that the horror ﬁ lm actually

induced fear in our subjects.

Cortisol

When we compare the subjects’ cortisol levels be-

fore and after each ﬁ lm presentation, we ﬁ nd that the

cortisol concentrations decrease signiﬁ cantly in both

the test (Wilcoxon; n=41; Z=–3,920; p=0,000; mean

cortisol level before ﬁ lm: 4,6; sd=3,28; after ﬁ lm:

3,57; sd=2,54) and the control situation (Wilcoxon;

n=42; Z=–5,370; p=0,000; mean level before ﬁ lm:

4,96; sd=3,09; mean level after ﬁ 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 ﬁ lm shows no signiﬁ cant results

(Spearman: n=41; r=–0,176; p>0,05) and no signiﬁ -

cant correlations between state-anxiety scores and cor-

tisol levels after the horror ﬁ 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 ﬁ ndings. A signiﬁ 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 signiﬁ cantly between

the horror and the control situation. During the pre-

Table 1: Correlations between daytime and cortisol levels (Spearman).

n Mw Sd r

Correlation between Cortisol 41 4,60 3,28 –,745 ,000

(ng/ml) at beginning of horror ﬁ lm

and the beginning time of horror ﬁ lm

Correlation between Cortisol 41 3,57 2,54 –,595 ,000

(ng/ml) at the end of horror ﬁ lm and

end time of horror ﬁ lm

Correlation between Cortisol 42 4,96 3,09 –,676 ,000

(ng/ml) at beginning of neutral ﬁ lm

and beginning time of neutral ﬁ lm

Correlation between Cortisol 42 3,19 2,06 –,652 ,000

(ng/ml) at end of neutral ﬁ lm

and the end-time of neutral ﬁ 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

sentation of the horror ﬁ lm, the subjects’ cortisol levels

dropped signiﬁ cantly less than during the control ﬁ lm

(Wilcoxon; n=41; Z=–2,138; p<0,05; mean difference

horror ﬁ lm: 1,03; sd=1,84; mean difference control:

1,76; sd=1,58).

Odour assessment experiment

In order to ﬁ 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 signiﬁ 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 inﬂ uence on

odour assessment, as no signiﬁ cant correlations could

be found between changes in cortisol levels in both the

horror and the neutral ﬁ lm situation and the percent-

age of correct decisions (Horror ﬁ lm: n=20; r=0,132;

p>0,05; Neutral ﬁ lm: n=21, r=–0,148; p>0,05).

If we look at the qualitative rating of the odour sam-

ples, we ﬁ nd signiﬁ cant differences between the assess-

ments of the “horror” and the “neutral” samples (see

table 2). We ﬁ nd that the odour samples from the hor-

ror ﬁ lm presentation were rated as signiﬁ cantly more

odourous (U-Test: n=635; Z= 2,948; p<0,01; MR hor-

ror ﬁ lm= 667,3; MR neutral ﬁ lm= 606, 56), and less

pleasant (U-Test: n= 633; Z= 2,044; p< 0,05; MR hor-

ror ﬁ lm= 613,52; MR neutral ﬁ 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 ﬁ lm= 649,58; MR neutral ﬁ lm=

617,37) and “smells like sex” (U-Test: n=633; Z=

–0,181; p>0,05; MR horror ﬁ lm=6363,35; MR neu-

tral ﬁ lm=632,64) between the test situations, the

women rated the samples from the horror ﬁ lm as more

“aggressive”, than the neutral ones (U-test: n=633;

Z=1,965; p<0,05; MR horror ﬁ lm= 653,58; MR neu-

tral ﬁ lm= 613,42).

Discussion

The ﬁ 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 signiﬁ cant increase in their state anxiety

levels in the test situation. We can therefore conclude

that the horror ﬁ 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’ ﬁ lm as-

sessments, as they rated the horror movie as signiﬁ -

cantly less boring, more frightening, suspenseful and

less funny than the neutral ﬁ 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

ﬁ 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 signiﬁ 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 signiﬁ cantly less during

the presentation of the horror ﬁ lm than during the

presentation of the neutral one. This result indicates

that the HHN axis was indeed stimulated by the horror

ﬁ 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 ﬁ nd that the female subjects were

indeed able to differentiate between the odour sam-

ples from the horror ﬁ lm and the neutral ﬁ lm situa-

tion. The expected 33% of correct assessments by pure

chance were signiﬁ cantly exceeded in our experiment.

This ﬁ 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 ﬁ 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-

niﬁ 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

REFERENCES

1 Doty RL. Odor guided behavior in mam-

mals. Experentia 1986; 42: 257–71.

2 Kohl J, Atzmueller M, Fink B, & Grammer K.

Human Pheromones: Integrating Neuro-

endocrinology and Ethology. Neuroendo-

crinol Lett 2001; 22(5): 319–31.

3 Spielberger CD, Gorsuch RL, Lushene RE.

Manual for the State-Trait Anxiety Inven-

tory. Palo Alto. Consulting Psychologists

Press; 1983.

4 Panksepp J. Affective neuroscience: The

foundations of human and animal emo-

tions. New York, Oxford. Oxford Plenum

Press; 1998.

5 Kirschbaum C, Hellhammer DH. Salivary

cortisol in psychoneuroendocrine re-

search: Recent developments and ap-

plications. Psychoneuroendocrinol 1994;

19(4): 313–33.

6 Hubert W, de Jong-Meyer R. Emotional

stress and saliva cortisol response. J Clin

Chem Clin Biochem 1989; 27: 235–7.

7 Kirschbaum C, Hellhammer DH. Response

variability of salivary cortisol under psy-

chological stimulation. J Clin Chem Clin

Biochem 1989; 27: 237.

8 Hubert W, Möller M, de Jong-Meyer R.

Film-induced amusement changes in sa-

liva cortisol levels. Psychoneuroendocri-

nol 1993; 18: 265–72.

9 Ockenfels M, Smyth J, Porter L, Kirsch-

baum C. Der Einﬂ uß alltäglicher Stresso-

ren (daily hassles) auf die Cortisolkonzen-

tration im Speichel. Verhaltenstherapie

1995; 5 (suppl 1); 16–20.

10 Van Eck M, Berkhof H, Nicolson N, Sulon

J. The effect of perceived stress, mood

states, and stressful daily events on

salivary cortisol. Psychosom Med 1996;

58(5): 447–58.

11 Smyth J, Ockenfels MC, Porter L, Kirsch-

baum C, Hellhammer DH, Stone AA.

Stressors and mood measured on a mo-

mentary basis are associated with sali-

vary cortisol secretion. Psychoneuroen-

docrinol 1998; 23(4): 353–70.

12 Von Frisch, K. Über einen Schreckstoff der

Fischhaut und seine biologische Bedeu-

tung: Z vergl Physiol 1941; 29: 46–145.

13 Wilson, EO. The sociogenesis of insect

colonies. Science 1985; 228: 1489–95.

14 Nunez J, Almeida L, Balderrama N, Giurfa

M. Alarm pheromone induces stress anal-

gesia via an opioid system in the honey-

bee. Physiol Behav 1997; 63(1): 75–80.

15 Mc Allister MK, Roitberg BD. Adaptive

suicidal behaviour in pea aphids. Nature

1987; 328: 797–9.

16 Ressler RH, Cialdini RB, Ghoca ML, Kleist

SM. Alarm pheromone in the earthworm

Lumbricus terrestris. Science 1968; 161:

597–9.

17 Brown GE, Chivers DP, Smith R, Jan F.

Localized defecation by pike: A response

to labelling by cyprinid alarm phero-

mone? Behav Ecol Sociobiol 1995; 36(2):

105–10.

18 Valenta JG, Rigby MK. Discrimination of

the odor of stressed rats. Science 1968;

161: 599–601.

19 Carr WC, Martorano RD, Krames L. Re-

sponses of mice to odors associated with

stress. J Comp Physiol Psych 1970; 71(2):

223–8.

20 Cocke R, Thiessen DD. Chemocommuni-

cation among prey and predator species.

Anim Learn Behav 1986; 14: 90–2.

21 Aitken RCB. A growing edge of measure-

ment of feelings. P Roy Soc Med 1969;

62: 989–93.

22 Kirschbaum C, Hellhammer DH. Salivary

cortisol in psychobiological research:

An overview. Neuropsychobiology 1989;

22(3): 150–69.

23 Hubert W, de Jong-Meyer R. Saliva corti-

sol responses to unpleasant ﬁ lm stimuli

differ between high and low trait anxious

subjects. Neuropsychobiology 1992; 25:

115–20.

“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 deﬁ 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 ﬁ ndings give yet another hint that

olfactory communication in humans is of great impor-

tance.

In Vitro and In Vivo Human Body Odor Analysis Method Using GO:PANI/ZNRs/ZIF−8 Adsorbent Followed by GC/MS

Article

Jul 2022
MOLECULES

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.

Humans and the Olfactory Environment

Article

Full-text available

Jun 2022

Peter Frost

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.

A Preliminary Investigation of Interspecific Chemosensory Communication of Emotions: Can Humans (Homo sapiens) Recognise Fear- and Non-Fear Body Odour from Horses (Equus ferus caballus)

Article

Full-text available

Dec 2021

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.

Fear Factor in Seeking Dental Care among Saudis during COVID-19 Pandemic

Article

Full-text available

Oct 2021

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.

Olfaction in the Multisensory Processing of Faces: A Narrative Review of the Influence of Human Body Odors

Article

Full-text available

Oct 2021

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.

Psychometric Validation of the Arabic Fear of Illness and Virus Evaluation

Article

Full-text available

Aug 2021
Int J Environ Res Publ Health

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.

Epilepsy and the smell of fear

Article

Full-text available

Aug 2021
EPILEPSY BEHAV

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.

Neurokommunikation im Eventkontext: Wie sich Erkenntnisse des Neuromarketings und endokrinologische Beeinflussung im Eventkontext einsetzen lassen

Chapter

Jan 2021

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.

Neural Circuits of Anxiolytic and Antidepressant Pherine Molecules

Article

Full-text available

Oct 2020
CNS SPECTRUMS

In this review, we describe proposed circuits mediating the mechanism of action of pherines , a new class of synthetic neuroactive steroids with demonstrated antianxiety and antidepressant properties, that engage nasal chemosensory receptors. We hypothesize that afferent signals triggered by activation of these peripheral receptors could reach subgroups of olfactory bulb neurons broadcasting information to gamma-aminobutyric acid (GABA ergic ) and corticotropin-releasing hormone (CRH) neurons in the limbic amygdala. We propose that chemosensory inputs triggered by pherines project to centrolateral (CeL) and centromedial (CeM) amygdala neurons, with downstream effects mediating behavioral actions. Anxiolytic pherines could activate the forward inhibitory GABA ergic neurons that facilitate the release of neuropeptide S (NPS) in the locus coeruleus (LC) and GABA in the bed nucleus of the stria terminalis (BNST) and inhibit catecholamine release in the LC and ventral tegmental area (VTA) leading to rapid anxiolytic effect. Alternatively, antidepressant pherines could facilitate the CRH and GABA ergic neurons that inhibit the release of NPS from the LC, increase glutamate release from the BNST, and increase norepinephrine (NE), dopamine (DA), and serotonin release from the LC, VTA, and raphe nucleus, respectively. Activation of these neural circuits leads to rapid antidepressant effect. The information provided is consistent with this model, but it should be noted that some steps on these pathways have not been demonstrated conclusively in the human brain.

Predator naïve minnows respond to their conspecific alarm substance but not the odour from a non‐native predator

Article

Jul 2020

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.

A growing edge of measurement of feelings

Article

Jan 1969
Proc Roy Soc Med

R.C.B. Aitken

Affective Neuroscience. The Foundations Of Human and Animal Emotions

Book

Jan 1998

Jaak Panksepp

Affective Neuroscience: The Foundations of Human and Animal Emotions

Article

Oct 2002

Sergio Paradiso

Mannual for the State-Trait anxiety inventory STAI (Form)

Book

Adaptive suicidal-behavior in pea aphids

Article

Aug 1987

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.

Chemocommunication among prey and predator species

Article

Mar 1986

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.

Über einen Schreckstoff der Fischhaut und seine biologische Bedeutung

Article

Jan 1942

K. von Frisch

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.

Localized defecation by pike: a response to labelling by cyprinid alarm pheromone?

Article

Feb 1995

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.

Salivary cortisol in psychoneuroendocrine research: Recent developments and applications

Article

Feb 1994
PSYCHONEUROENDOCRINO

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.

Saliva Cortisol Responses to Unpleasant Film Stimuli Differ between High and Low Trait Anxious Subjects

Article

Feb 1992

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.