Department of Psychiatry,
University of Rome, Italy
Traditionally, research on human stress has
relied mostly on physiological and psychological
measures with a relatively minor emphasis on the
behavioral aspects of the phenomenon. Such an
approach makes it difficult to develop valid
animal models of the human stress syndrome. A
promising approach to the study of the
behavioral correlates of stress is to analyze
those behavior patterns that ethologists have
named displacement activities and that, in
primates, consist mostly of self-directed
behaviors. In both nonhuman primates and human
subjects, displacement behavior appears in
situations characterized by social tension and
is likely to reflect increased autonomic
arousal. Pharmacological studies of nonhuman
primates have shown that the frequency of
occurrence of displacement behavior is increased
by anxiogenic compounds and decreased by
anxiolytic drugs. Ethological studies of healthy
persons and psychiatric patients during
interviews have found that increased
displacement behavior not only correlates with a
subjective feeling state of anxiety and negative
affect but also gives more veridical information
about the subject's emotional state than verbal
statements and facial expression. The
measurement of displacement activities may be a
useful complement to the physiological and
psychological studies aimed at analyzing the
correlates and consequences of stress.
Introduction
The phenomenology of the stress syndrome
involves three distinct response modalities:
physiological reactions, subjective feelings and
behavioral changes (Chrousos and Gold, 1992).
Traditionally, studies of human subjects have
concentrated on the measurement of physiological
and subjective correlates of stress. Much less
attention has been paid to the description and
measurement of the behavioral changes that are
elicited by exposure to stressful situations.
While this approach has contributed much to our
understanding of the stress syndrome, it is not
without its limitations. These include the
difficulty in comparing human and animal data
and reliance on selfreports that are of unknown
reliability. Not knowing how a subject feels or
what are its psychic experiences restricts the
animal researcher to inferences based on
observable behaviors. Conversely, assessment of
stress in human subjects is based almost
exclusively on the evaluation of the psychic
experiences as voiced by the subject. Because of
this difference between the methods employed in
human and animal studies, the integration of
human and animal data is generally difficult and
sometimes impossible. Another problem is the
reliability of subjects' reports of their
psychological status. Selfreports may be
unreliable not only because of conscious
deception or unconscious masking but also due to
inaccurate self-evaluation. The complexity of
the relationship between subjective and
objective aspects of mental distress becomes
clear on reading the results of alexithymia
studies in this article. A prerequisite for the
behavioral study of stress in human subjects is
the identification and description of motor
patterns that are consistently associated with
the stress response and that have a phylogenetic
basis. In this regard, a promising approach is
the analysis of those behavior patterns that
ethologists have named displacement activities
and that consist mostly of movements focused on
one's own body such as self-touching, scratching
and self-grooming. The aim of this article is to
review ethological, physiological and
pharmacological data suggesting that
displacement activities are a valid behavioral
measure of stress in nonhuman primates and human
subjects.
The ethology and physiology of
displacement activities
Ethologists commonly use the term
"displacement activity" to designate behavior
patterns occurring in situations in which they
would not expect to observe them (McFarland,
1966). For example, a male three-spined
stickleback (Gasterosteus aculeatus ), in the
midst of courting a female, may suddenly swim to
his nest and display fanning behavior, i.e. the
parental activity that normally serves to
ventilate the eggs in the nest. It is hard to
explain how such a behavior is relevant to
either parental care (as there are still no
developing eggs in the nest) or courtship (as
the fanning activity does not appear to
influence the female). Such "irrelevant"
behavior is common during fighting, agonistic
contest, courtship and play of all vertebrate
animals. It has been commonly referred to as
"displacement behavior" because early
ethologists thought it was not "fed" from its
own sources but by "displaced" energy
originating from a different source blocked in
its normal expression (Kortmulder, 1998).
Displacement activities are common in
situations of motivational conflict in which
tendencies to perform more than one activity are
simultaneously expressed. For example, the
displacement fanning of the male threespined
stickleback described above is most likely to
occur when there is equilibrium between the
conflicting tendencies to attack and to court a
female that enters the territory. Displacement
activities also appear in situations in which a
goal-directed behavior is thwarted by internal
or external factors (e.g. frustration). In
nonhuman primates, by far the most common
displacement activities are those "comfort
behaviors" that have something to do with body
care such as grooming, scratching, shaking,
stretching or yawning. Much less common
are feeding, sleeping, sexual mounting, and
parental behavior. In human beings, displacement
activities include both self-directed behaviors
similar to primate grooming behavior (e.g. head
scratching, beard stroking) and aimless,
iterative manipulation of objects (e.g. sucking
on pens, twisting wedding rings, fingering
handkerchiefs). Table I lists the behavior
patterns included in the category "displacement
behavior" of the Ethological Coding System for
Interviews (ECSI; Troisi, 1999), an ethogram
designed for measuring nonverbal behavior during
interviews. The frequency of occurrence of
displacement behavior as defined by the ECSI is
fairly high, ranging from 20 to 100% of the
sample intervals.
Such a wide variation depends on a number of
factors, including the content of the interview,
the age and sex of the interactants, and the
diagnostic status of the interviewee (normal
subjects, psychiatric patients with anxiety,
depressive, or psychotic disorders). The fact
that displacement activities derive from
behaviors that, in the appropriate context,
fulfil practical functions raises the question
of how to make a distinction between these
normal behaviors and the corresponding
displacement activities. In some cases, there
are morphological differences between a
displacement activity and the same activity
carried out in its normal context. Studying
behavioral indicators of anxiety in captive
group-living chimpanzees (Pan troglodytes ),
Baker and Aureli (1997) found that rough
scratching (defined as raking one's own hair or
skin with fingernails including large movements
of arm), but not gentle scratching (defined as
raking one's own hair or skin with fingernails
including mainly movements of hand or fingers),
increased during periods with high levels of
neighbor vocalization (see the section on
behavioral studies in nonhuman primates).
Russell and Russell (1985) argued that "a
displacement activity is always fragmentary and
incomplete, when compared with the same activity
carried out in its normal mood and context." (p.
31). However, in most cases, displacement
behavior can only be defined by its context of
occurrence, not by its morphology, and it is
often impossible to indicate exactly where a
displacement activity merges into original
behavior (Kortmulder, 1998). The vagueness of
the boundaries between the two categories of
behavior is further confirmed by the finding
that displacement activities are, to some
extent, influenced by the same external stimuli
that normally elicit the corresponding original
behavior. For example, domestic cocks show bouts
of feeding or drinking during fights. If water
is available displacement drinking occurs, and
if food is available displacement feeding
occurs.
Another question that needs to be addressed
is the relationship between displacement
activities and other behaviors that apparently
serve no obvious purpose. Some terms that have
been used in the literature are in fact
synonymous of displacement activities (i.e.
ritualized conflict behavior, vacuum behavior,
irrelevant behavior, incongruous behavior,
redirected behavior). In contrast, the term
"stereotypy" has been used more ambiguously and
may indicate motor acts that differ from
displacement activities in terms of etiology and
physiological mechanisms. Whereas displacement
activities are normal behaviors that can be
observed in natural settings, "true"
stereotypies are pathological behaviors
exhibited by individuals subjected to social and
sensory isolation (Ridley and Baker, 1982). In
nonhuman primates living in captivity,
stereotypies can take the form of self-clasping,
compulsive masturbation, head tossing, rocking,
stereotyped pacing, or bouncing in place (Erwin
and Deni, 1979). Similar behaviors have been
observed in institutionalized patients suffering
from psychotic disorders or mental retardation.
These behaviors do not resemble, and should not
be confused with, displacement activities. Less
clear is the relationship between displacement
activities and those repetitive actions fixed in
form and orientation that have been observed in
farm animals and that have been claimed to
reduce tension or anxiety through release of
brain opioids (Dantzer, 1986). Although these
behaviors have been labeled as "stereotypies",
the fact that they are self-directed behaviors
typically observed in situations of conflict or
frustration suggests a significant overlap with
displacement activities. The hypothesis that
displacement behavior may result from autonomic
processes activated during stressful situations
has been repeatedly advanced in the ethological
literature. For example, several authors have
suggested that, in a variety of species, the
mechanism responsible for displacement
activities consisting of brief skin-care
patterns involves peripheral somatic changes
(e.g. increased peripheral blood flow,
sweating), which may in turn lead to behavioral
responses (e.g. scratching) (Delius, 1967;
Hinde, 1982). However, displacement behavior
might be directly controlled by central
mechanisms as well. In rats, the
intracerebroventricular injection of
corticotropin-releasing factor (CRF) (Dunn and
File, 1987) or adrenocorticotropic hormone
(ACTH) (Gispen and Isaacson, 1981) causes a
remarkable elevation of grooming, a
self-directed behavior commonly observed under
stressful conditions. In primates, direct
evidence that displacement activities are
associated with stress-related physiological
changes is lacking, even though circumstantial
evidence suggests that this may be the case.
Studies of captive macaques have found that both
heart rate and frequency of scratching increase
following an episode of aggression and both are
reduced after the individual is groomed by other
monkeys (Schino et al., 1988; Aureli et al.,
1989; Boccia et al., 1989).
Nonhuman primate studies
Behavioral Studies Behavioral studies of
nonhuman primates living in groups have
demonstrated that the occurrence of displacement
behavior is associated with a variety of social
situations that are apparently quite
heterogeneous but which have in common
uncertainty and anxiety as the stressful causal
factors (Maestripieri et al., 1992b).
Uncertainty about assessment of dominance rank
is a social situation associated with high
levels of displacement activities. Schino et al.
(1990) found that, when two unfamiliar female
long-tailed macaques (Macaca fascicularis ) were
paired in a cage, the delayed establishment of
dominance relationships caused a sharp increase
in the frequency of scratching and
self-grooming. Such an increase did not occur
when the pairing involved either unfamiliar
monkeys who rapidly displayed behavioral
indicators of status differences or familiar
individuals with already established dominance
relationships. Uncertainty about the risk of
being attacked is another situation commonly
associated with increased levels of displacement
activities. Troisi and Schino (1987) found that
the rate of self-grooming in female long-tailed
macaques increased when the subjects were in
spatial proximity (within 1m) with the dominant
male. Adult female macaques are attracted by the
dominant male and have the tendency to approach
him to groom him or to sit in bodily contact
with him. However, spatial proximity with the
dominant male is a potentially risky situation
because sometimes the male reacts by attacking
the approaching female. Baker and Aureli (1997)
found that, in captive group-living chimpanzees,
the rate of scratching increased after the
exposure to vocalizations of neighboring groups,
an acoustic signal associated with a high risk
of impending intragroup aggression. Displacement
activities have also been reported to occur
immediately after agonistic interactions. In
longtailed macaques and olive baboons (Papio
anubis ), intragroup aggression is followed by a
dramatic increase in the rate of scratching, in
both the victim of aggression (Aureli and van
Schaik, 1991; Aureli, 1992; Castles and Whiten,
1998) and the aggressor (Aureli, 1997; Castles
and Whiten, 1998). Such an increase reflects the
uncertainty of the post-conflict situation. The
victim of aggression cannot be sure it will be
tolerated around resources by the former
aggressor and it is more likely to be attacked
again, whereas the aggressor may lose the
support of its previous opponent for future
cooperative actions (see the review by Aureli
and Smucny (2000) for data supporting such an
interpretation). Displacement behavior appears
to be a sensitive measure of the intensity of
the stress experienced in the post-conflict
phase. Aureli (1997) found that, in longtailed
macaques, scratching rates were higher after
unreconciled conflicts between "friends" (i.e.
partners with previous high affiliation rates)
than after those between other individuals. This
finding has two important implications for a
better understanding of the link between social
stress and displacement behavior. First,
stressrelated increase in displacement
activities is a response of variable intensity
influenced by the specific characteristics of
the social context rather than a none-or-all
reaction. Second, anxiety elicited by a
potential danger for one self's physical
integrity or social status is not the only
stressful situation correlated with an increase
in the rate of displacement activities. Also a
perceived danger to either a valuable
relationship or a significant other can be the
proximate cause of this behavioral response.
Data illustrating this latter aspect come from
studies of mother&endash;infant pairs.
Studying maternal behavior in captive
Japanese macaques (Macaca fuscata ), Troisi et
al. (1991) found positive correlations between
rates of scratching and maternal possessiveness.
Thus, mothers who were most apprehensive about
their infants and adopted a highly protective
style of mothering were also those who scratched
themselves more. In a study of maternal anxiety
in rhesus macaques (Macaca mulatta ),
Maestripieri (1993) found that the rate at which
mothers scratched themselves increased
significantly when their infants moved away from
them and when the infants were in spatial
proximity to the adult male or higher-ranking
adult females. Furthermore, the rate of maternal
scratching increased when infants approached or
were approached by individuals who frequently
harassed them. Pharmacological Studies In
nonhuman primates, evidence indicating an
association between stress and displacement
activities is not limited to behavioral
observations. Several studies have employed
experimental manipulations to investigate the
neurobiological correlates of displacement
behavior and its relationships with negative
emotional states. Redmond and Huang (1979)
demonstrated that the electrical and
pharmacological activation of the locus
coeruleus, a major brain noradrenergic nucleus
which mediates anxiety-related behaviors,
elicits scratching in the stump-tailed macaque
(Macaca arctoides ). In line with this finding,
treatment of chair-restrained rhesus monkeys
with the anxiogenic compound beta-CCE has been
reported to elicit not only physiological
changes typically associated with the stress
response but also a variety of behavioral
changes including increased scratching (Ninan et
al., 1982). Studies conducted in more
ecologically-valid settings have confirmed the
association between displacement activities and
anxiety. Schino et al. (1991) studied the
effects of the acute administration of
lorazepam, an anxiolytic drug, on scratching by
group-living female long-tailed macaques with
particular reference to the modulating influence
of social rank. Lorazepam reduced scratching in
both high-ranking and low-ranking subjects but
the effect was more marked in low-ranking
females. The authors explained this finding
arguing that especially low-ranking animals are
prone to experience stressful social situations.
In effect, they found that baseline scratching
was higher in low-ranking than in high-ranking
monkeys. Maestripieri et al. (1992a)
investigated the effects of anxiolytic and
anxiogenic treatments on the behavior of rhesus
monkey infants living with their mothers and
other group companions. These authors found that
the anxiogenic beta-CCE increased the frequency
of both infant scratching and contact-seeking
behavior with the mother. In contrast, the acute
administration of the anxiolytic midazolam
reduced the rate of infant scratching.
Schino et al. (1996) investigated the acute
effects of two benzodiazepine receptor ligands
with opposite effects (i.e. the anxiolytic
lorazepam and the anxiogenic FG 7142) on the
displacement activities of seven male
long-tailed macaques living in social groups. In
line with the hypothesis of the study, lorazepam
caused a dosedependent decrease in the frequency
of displacement activities, whereas the
beta-carboline FG 7142 caused a dose-dependent
increase (Fig. 1). Drug effects on other
behaviors that could alter the emotional state
of the animal or the cutaneous stimuli eliciting
displacement activities did not mediate these
changes. The most interesting finding of this
study was that displacement activities were
apparently more sensitive to anxiolytic
treatment than other behavior patterns
indicative of an anxiety state. The non-sedative
low doses of lorazepam that were used did not
affect either visual scanning of the social
environment nor fear responses directed to
dominant males, two behavior patterns that
reflect anxiety as demonstrated by their
increase after treatment with FG 7142.
Nevertheless, the same doses of lorazepam were
sufficient for decreasing the frequency of
displacement activities.
Human studies
In the literature on human nonverbal
communication, displacement activities have been
referred to by many labels, including synkinetic
movements (Allport and Vernon, 1933), autistic
movements (Krout, 1935), self-manipulations
(Rosenfeld, 1966a), body-focused movements
(Freedman and Hoffman, 1967), self-adaptors
(Ekman and Friesen, 1969), and body manipulators
(Ekman, 1977). Even though the interest in these
behavior patterns dates back to the 1930s, the
evidence linking stress with self-directed
behavior in human subjects is relatively limited
when compared to the extensive literature on
nonhuman primates. Self-contact actions were
found to increase in response to experimentally
induced withdrawal of socially supportive
nonverbal behavior (Rosenfeld, 1967), and their
rate of occurrence was found to correlate with
ratings of anxiety and guilt (Ekman and Friesen,
1972), as well as disapproval (Rosenfeld,
1966b). Waxer (1977) found that raters naive to
the content of a clinical interaction were able
to identify the presence of anxiety and its
intensity on the basis of nonverbal cues alone.
Examining silent video segments drawn from
interviews with psychiatric patients, raters
perceived nonillustrative hand movements (e.g.
stroking oneself) as the most salient cues to
anxiety and were able to distinguish between
patients with high and low scores on a
self-rating scale for anxiety. Shreve et al.
(1988) analyzed the nonverbal behavior of 25
patients during their interactions with family
practitioners. Patient interviews were
categorized on the basis of topic content into
two types: dual-agenda interviews and
single-agenda interviews. Dual-agenda interviews
contained two conditions: an initial topic (i.e.
first agenda) judged not to be the most
significant complaint expressed by the patient,
and a later presentation of a psychosocial need
that was emotionally relevant to the patient
(i.e. hidden agenda). Single-agenda interviews
contained only a single topic presented by the
patient. Hand-to-body self-touching occurred
significantly more often during patient
presentation of conflicted emotional topics
(i.e. hidden agendas), while frequencies of
speech-illustrative gestures did not differ for
type of agenda presented. Troisi et al. (1998)
used the Ethological Coding System for
Interviews (ECSI) to analyze the nonverbal
behavior of 28 young men with a diagnosis of
recent-onset schizophrenia.
Most of these patients had never received
neuroleptic treatment and all of them were kept
drug-free for at least a week prior to being
interviewed. At the end of the interview, the
clinician rated patients' symptoms on the Brief
Psychiatric Rating Scale (BPRS), a psychometric
instrument that covers the entire range of
schizophrenic psychopathology. There was a
positive and significant correlation between
displacement behavior and the anxiety/depression
subscale of the BPRS. Those patients who were
rated as most anxious and/or depressed by the
clinician showed a higher frequency of
displacement activities during the interview
(Fig. 2). Taken together, the results of these
studies indicate that, in human subjects,
displacement activities may be elicited by
stressful stimuli and may reflect an emotional
condition of negative affect (i.e. anxiety
and/or depression). However, the relationship
between stress-related emotional state and
displacement activities may be more complex than
that emerging from the findings reported above,
as suggested by two recent studies of nonverbal
behavior correlates of alexithymia (Troisi, et
al., 1996; 2000. Alexithymia is a personality
trait distributed normally in the general
population which involves a marked difficulty in
identifying feelings and describing them to
other people (Bagby and Taylor, 1997).
Alexithymic individuals know very little about
their own feelings and, in most instances, are
unable to link negative affect with memories,
fantasies, or specific situations. The
alexithymia construct is relevant to stress
research because a deficit in modulating
distressing emotions through cognitive
processing might result in exacerbated responses
in the autonomic nervous system. Several
psychophysiological studies have yielded
preliminary evidence that alexithymic
individuals show higher tonic levels of
sympathetic arousal than nonalexithymic
individuals (Friedlander et al., 1997; Infrasca,
1997), and a decoupling of the autonomic and
cognitive responses to laboratory stressors
(Papciak et al., 1985; Martin and Pihl, 1986;
Rabavilas, 1987). In addition, there is evidence
that alexithymia is associated with a variety of
psychiatric and medical disorders (Taylor,
2000). Using the ECSI, Troisi, et al., 1996
studied the relationship between alexithymia and
nonverbal behavior in 24 young volunteers free
of medical and psychiatric disorders. Multiple
regression analysis controlling for the levels
of anxiety and depression revealed that the
frequency of self-directed behavior during the
interview was a significant predictor of
alexithymic traits. Those subjects who had more
difficulty identifying and describing their
feelings scored higher on the category of the
ECSI measuring displacement activities. Similar
findings have emerged from a more recent study
conducted on 30 patients with depressive or
anxiety disorders (Troisi et al., 2000). The
patients with more pronounced alexithymic
features showed a significantly higher frequency
of displacement activities during
interviews.
At the same time, these patients reported
levels of self-rated anxiety and depression
equivalent to those reported by nonalexithymic
patients. These findings have two important
implications for studies of the relationship
between stress and displacement activities.
First, one should not expect to find the
occurrence of displacement behavior invariably
associated with self-reports of negative affect.
Some individuals have a reduced ability to
experience and regulate affects cognitively, and
this can produce an apparent dissociation
between subjective appraisal of emotion and
nonverbal behavior reflecting increased
emotional arousal. Second, in stress research,
the recording of displacement activities may be
a useful complement to psychological assessment
because nonverbal behavior can give more
veridical information about the subject's
emotional state than verbal statements. This
concept was originally expressed by Ekman and
Friesen (1969) who coined the term "emotional
leakage". These authors argued that the behavior
patterns that they labeled as selfadaptors
(largely corresponding to the displacement
activities listed in the ECSI) "leak more," that
is, they reflect the subject's affective state
more accurately than self-reports on emotion
which are often subject to either greater
conscious deception or unconscious masking.
Symptoms or adaptive responses?
Most of the physiological changes occurring
during acute stressful situations are adaptive
responses that attempt to counteract the effects
of the stressors in order to reestablish
homeostasis (Chrousos and Gold, 1992). Could we
say the same for displacement behavior? Are
displacement activities behavioral components of
the adaptive stress response? Studies of
non-primate species suggest that this is the
case. Behavioral "stereotypies" attenuate
physiological measures of stress (Dantzer and
Morme`de, 1985) and stimulate endorphin
production (Cronin et al., 1986) in pigs.
Displacement chewing and gnawing reduce the
stress-related activation of the
hypothalamo-pituitary&endash; adrenal axis in
mice exposed to novel environment (Hennessy and
Foy, 1987) and in rats exposed to electric shock
(Levine et al., 1989). In rats and mice exposed
to a brightly lit novel environment, animals
that engaged in displacement chewing of inedible
objects displayed significantly lower activation
of the prefrontal cortical dopaminergic system,
which is generally observed in stressful
situations (Berridge et al., 1999). Since the
attenuation of the stressor-induced increase in
dopaminergic transmission within the prefrontal
cortex is similar to that observed following
administration of anxiolytics and opposite to
that observed following administration of
anxiogenics, Berridge et al. (1999) have
suggested that displacement chewing may serve an
anxiolytic function. In primates, very few
studies have tested the hypothesis that
displacement activities may be adaptive
responses evolved to cope with stress. In a
prosimian species, the small-eared bushbaby
(Otolemur garnettii ), the animals that
performed more displacement activities (foot and
chest rubbing) in a novel environment also
exhibited lower cortisol responses to restraint
stress (Watson et al., 1999). Among olive
baboons living freely in a national park in
Africa, those subordinate males that were most
likely to displace aggression onto a third party
after losing a fight had significantly lower
basal glucocorticoid concentrations compared to
the remaining subordinate cohort (Virgin and
Sapolsky, 1997). However, the relevance of this
finding to the stress-reducing function of
displacement activities is dubious. Even though
fighting has been included among primate
displacement activities (Russell and Russell,
1985), redirected aggression might be a
physiological and behavioral phenomenon
completely different from self-directed
behaviors such as scratching or self-grooming.
In humans, the evidence is, at best,
circumstantial and limited to the finding that
gentle body touching causes relaxation and a
reduction in heart rate (Drescher et al., 1980).
Several considerations concur in suggesting that
displacement activities are behavioral
components of the adaptive stress response,
probably causing anxiolytic effects. They are
widespread across the phylogenetic scale, their
frequency of occurrence is fairly high in both
natural and experimental settings, and
individuals free from behavioral pathologies
exhibit them. Nevertheless, definitive evidence
for a physiological and/or behavioral function
of displacement activities performed by nonhuman
primates and humans under stress is still
lacking.
Conclusions
The data reviewed in this article suggest
that displacement behavior is a valid measure of
stress in nonhuman primates and human subjects.
The measurement of displacement activities can
be introduced into studies aimed at analyzing
the behavioral correlates of human stress as a
useful complement to physiological and
psychometric assessments. Clearly, the use of
displacement activities as a behavioral measure
of stress requires a greater investment of time
and resources than is needed for most of the
procedures currently employed in
psychophysiological research. Direct observation
and quantitative recording of behavior are
time-consuming and much more complicated than
psychometric assessment. However, what is lost
in The fact that there are already sufficient
data to justify the use of displacement
activities in human stress research does not
mean that we have a complete knowledge about the
causation and function of these behavior
patterns. Many questions remain to be answered.
What are the physiological mechanisms implicated
in the proximate causation of displacement
behavior? Do displacement activities serve an
adaptive role in reducing autonomic activation?
Are different types of displacement activities
equivalent in terms of validity for measuring
stress? To answer these and other questions,
further research on human displacement behavior
should be based on studies that integrate
ethological observation, physiological measures,
and psychometric assessment. The correspondence
between physiological changes and variations in
the frequency of occurrence of displacement
activities should be measured in subjects
exposed to different levels of experimental
social stress. Concurrent psychometric
assessment should clarify whether or not
self-reported levels of anxiety co-vary with the
behavioral and physiological measures. The
short- and long-term effects of displacement
activities on the physiological parameters
implicated in the stress response should be
evaluated. If an anxiolytic effect of
displacement activities were demonstrated,
investigators should ascertain whether different
motor patterns included in the category of
displacement behavior (e.g. scratching vs.
gentle and prolonged selfcontact) differ in
terms of efficacy in calming down the subject
under stress.
TABLE I Definition of behavior patterns
included in the category "displacement behavior"
of the Ethological Coding System for Interviews
(ECSI)
1. Groom. The fingers are passed through the
hair in a combing movement.
2. Hand&endash;face. Hand(s) in contact with
the face.
3. Hand&endash;mouth. Hand(s) in contact
with the mouth.
4. Scratch. The fingernails are used to
scratch part of the body, frequently the
head.
5. Yawn. The mouth opens widely,
roundly and fairly slowly, closing more swiftly.
Mouth movement is accompanied by a deep
breath
and often closing of the eyes and lowering
of the brows.
6. Fumble. Twisting and fiddling finger
movements, with wedding ring, handkerchief,
other hand, etc.
7. Twist mouth. The lips are closed, pushed
forward and twisted to one side.
8. Lick lips. The tongue is passed over the
lips.
9. Bite lips. One lip, usually the lower, is
drawn into the mouth and held between the
teeth.
