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Psychologie selectie
CHAPTER 1
Early Landmarks in the Biopsychological Investigation of Emotion.
Darwin argued that particular emotional responses, such as human facial expressions, tend
to accompany the same emotional states in all members of a species: theory of the
evolution of emotion:
1. Expression of emotions evolve from behaviors that indicate what an animal is likely to
do next.
2. If the signals provided by such behaviors benefit the animal that displays them, they
will evolve in ways that enhance their communicative function, and their original
functions may be lost.
3. Opposite messages are often signaled by opposite movements and postures (=
principle of antithesis).
According to the James-Lange theory (1884), emotion-
inducing sensory stimuli are received and interpreted by
the cortex, which triggers changes in the visceral organs
via the autonomic nervous system and in the skeletal
muscles via the somatic nervous system. Then, the
autonomic and somatic responses trigger the experience
of emotion in the brain.
According to the Cannon-Bard theory (1915),
emotional stimuli have two independent excitatory effects:
they excite both the feeling of emotion in the brain and the
expression of emotion in the autonomic and somatic
nervous systems. That is, the Cannon-Bard theory, in
contrast to the James-Lange theory views emotional
experience and emotional expression as parallel
processes that have no direct causal relation.
According to the James-Lange theory, emotional
experience depends entirely on feedback from autonomic
and somatic nervous system activity; according to the
Cannon-Bard theory, emotional experience is totally
independent of such feedback. Both have proved to be
incorrect.
According to the modern biopsychological view
each of the three principal factors in emotional response –
the perception of the emotion-inducing stimulus, the
autonomic and somatic responses to the stimulus, and
the experience of the emotion can influence the other two.
Sham rage
Bard (1929) referred to the exaggerated, poorly directed aggressive responses as sham
rage. This can be elicited in cats whose cerebral hemispheres have been removed down to,
but not including, the hypothalamus. Bard concluded that the hypothalamus is critical for the
expression of aggressive responses and that the function of the cortex is to inhibit and direct
these responses.
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Limbic system and emotion
In 1937, Papez proposed that emotional expression is controlled by several interconnect
nuclei and tracts that ring the thalamus. Some of the key structures in this circuit are: the
amygdala, mammillary body, hippocampus, fornix, cingulate cortex, septum, olfactory, bulb
and hypothalamus. Papez proposed that emotional states are expressed through the action
of the other structures of the circuit on the hypothalamus and that they are experienced
through their action on the cortex (= limbic system theory of emotion).
Klüver-Bucy Syndrome
In 1939, Klüver and Bucy observed a striking syndrome in monkeys
whose anterior temporal lobes had been removed. This Klüver-
Bucy syndrome includes the following behaviors: consumption of
anything edible, increased sexual activity often directed at
inappropriate objects, a tendency to repeatedly investigate familiar
objects, a tendency to investigate objects with the mouth and lack of
fear. In primates, most of the symptoms of the Klüver-Bucy
syndrome have been attributed to the amygdala, a structure that
has played a major role in research on emotion.
Emotions and the Autonomic Nervous system
The James-Lange and Cannon-Bard theories differ in their views of the emotional specific of
the autonomic nervous system (ANS) the James-Lange theory says that different emotional
stimuli induce different patterns of ANS activity and that these different patterns produce
different emotional experiences. In contrast, the Cannon-Bard theory claims that all
emotional stimuli produce the same general pattern of sympathetic activation, which
prepares the organism for action.
Evidence indicates that not all emotions are associated with the same pattern of ANS
activity; on the other hand, there is no evidence that each emotion is characterized by a
distinct pattern of ANS activity.
Polygraphy
Polygraphy is a method of interrogation that employs ANS indexes of emotion to infer the
truthfulness of a person’s responses. The usual interrogation method is the control-
question technique, in which the physiological response to the target question is compared
with the physiological responses to control questions. The assumption is that lying will be
associated with greater sympathetic activation. However, some questions are likely to elicit
an emotional reaction regardless of their guilt or innocence. The guilty-knowledge
technique (or concealed information test), circumvents this problem. The polygrapher must
have a piece of information concerning the crime that would be known only to the guilty
person. Rather than attempting to catch the suspect in a lie, the polygrapher simply assess
the suspects reaction to a list of actual and contrived details of the crime. Innocent suspects
react to all such details in the same way; the guilty react differentially.
Emotions and facial expressions
Several early studies found that people of different cultures make similar facial expressions
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in similar situations and that they can correctly identify the emotional significance of facial
expressions displayed by people from cultures other than their own.
Ekman and Friesen concluded that the facial expressions of the following six
emotions are primary: surprise, anger, sadness, disgust, fear and happiness.
The hypothesis that our facial expressions influence our emotional experience is called the
facial feedback hypothesis. Rutledge and Hupka instructed volunteers to assume one of
two patterns of facial contractions while they viewed a series of slides; the patterns
corresponded to happy or angry faces, although the volunteers were unaware of that. The
hypothesis was confirmed, but the effects were small.
There are two ways of distinguishing true expressions from false ones. First, micro-
expressions (brief facial expressions) of the real emotions often break through the false one.
Such micro-expressions last only about 0,05 second, but they can be detected with practice.
Second, there are often subtle difference between genuine facial expressions and false ones
that can be detected by skilled observers. Current perspectives:
1. It is now clear that Ekman’s six primary facial expressions of emotional rarely occur in
pure form.
2. The existence of other primary emotions has been recognized.
3. Body cues are known to play a major role in expressions of emotions.
4. There is evidence that Ekman’s six primary facial expressions may not be as universal
as originally believed.
Fear, defense, and aggression
Fear is the emotional reaction to threat; it is the motivating force for defensive behaviors.
Defensive behaviors are behaviors whose primary function is to protect the organism from
threat or harm. In contrast, aggressive behaviors are behaviors whose primary function is
to threaten or harm.
Types of aggressive and defensive behaviors
Blanchard and Blanchard have derived rich descriptions of rat intraspecific aggressive and
defensive behaviors by studying the interactions between the alpha male – and the
dominant male – of an established mixed sex colony and a small male intruder.
Based on the numerous detailed descriptions of aggressive and defensive behavior
provided by the Blanchards, Pellis and colleagues, and other biopsychologists, most
researchers now distinguish among different categories of such behaviors. These categories
of aggressive and defensive behaviors are based on three criteria:
1. Their topography (form)
2. The situations that elicit them
3. Their apparent function.
The analysis of aggressive and defensive behaviors had led to the development of the
target-site concept (= the idea that the aggressive and defensive behaviors of an animal
are often designed to attack specific sites on the body of another animal while protecting
specific sites on its own).
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Aggression and testosterone
The fact that social aggression in many species occurs more commonly among males than
among females is usually explained with reference to the organizational and activational
effects of testosterone. The extensive comparative research literature on testosterone and
aggression has been reviewed several times. Here are the major conclusions (Soma et al):
• Testosterone increases social aggression in the males on many species.
• In some species, castration has no effect on social aggression; in still others, castration
reduces social aggression during the breeding season but not at other times.
• The relation between aggression and testosterone levels is difficult to interpret because
engaging in aggressive activity can itself increase testosterone levels.
• The blood level of testosterone, is not the best measure. What matters more are the
testosterone levels in relevant areas of the brain.
In human males, aggressive behavior does not increase at puberty as testosterone levels in
the blood increase; aggressive behavior is not eliminated by castration and it is not
increased by testosterone injections. Most seemingly aggressive outbursts in humans are
overreactions to real or perceived threat.
NEURAL MECHANISMS OF FEAR CONDITIONING
Fear conditioning is the establishment of fear in response t o a
previously neutral stimulus by presenting it before the delivery of an
aversive stimulus.
Amygdala and fear conditioning
LeDoux and his colleagues began their search for the neutral
mechanisms of auditory fear conditioning by making lesions in the
auditory pathways of rats. They found that bilateral lesions to the
medial geniculate nucleus blocked fear conditioning to a tone, but
bilateral lesions to the auditory cortex did not. This indicated that for
auditory fear conditioning to occur, it is necessary for signals elicited
by the tone to reach the medial geniculate nucleus but not the
auditory cortex. It also indicated that a pathway from the medial
geniculate nucleus to a structure other than the auditory cortex plays
