Chapter 14 - Emotion, Aggression and Stress Flashcards
EMOTIONS and their EVOLUTION
An EMOTION has two major components:
1) a PHYSICAL SENSATION;
2) a conscious, SUBJECTIVE EXPERIENCE.
After extensive observation of facial expressions produced by humans and other primates, Darwin argued that emotional expression evolved. Emotions might have helped our ancestors by providing survival advantages:
- they contribute to general AROUSAL - when the brain perceives a situation requiring action, emotions provide the arousal needed to trigger a response.
- they have a SOCIAL ROLE - nonverbal communication, consisting of FACIAL EXPRESSION and BODY LANGUAGE, provides an important source of social information.
3 THEORIES OF EMOTION
3 classical THEORIES OF EMOTION have been advanced in attempt to understand the relationship between its two components, namely the physiological experience and the subjective feeling. They are:
1) the JAMES-LANGE THEORY;
2) the CANNON-BARD THEORY;
3) the SCHACHTER-SINGER TWO-FACTOR THEORY.
the JAMES-LANGE THEORY
The JAMES-LANGE THEORY suggests that an awareness of our physical state leads to the identification of a subjective feeling. The theory assumes that physical states related to each type of feeling are distinct from one another and that we can label these physical states as separate feelings.
Schematised:
1) PERCEIVED STIMULUS;
2) SPECIFIC PHYSICAL RESPONSE;
3) SUBJECTIVE FEELING.
the SCHACHTER-SINGER TWO-FACTOR THEORY
According to the SCHACHTER-SINGER TWO-FACTOR THEORY, a stimulus first produces a general, ambiguous, non-specific arousal. Once aroused, we make a conscious, cognitive appraisal of our circumstances, which allows us to identify our subjective feelings.
Schematised:
1) PERCEIVED STIMULUS;
2) GENERAL PHYSICAL RESPONSE;
3) COGNITIVE ASSESSMENT;
4) SUBJECTIVE FEELING.
the CANNON-BARD THEORY
The CANNON-BARD THEORY proposes that the subjective and physical responses occur simultaneously and independently.
Schematised:
1) PERCEIVED STIMULUS;
2) PHYSICAL RESPONSE and SUBJECTIVE FEELING.
FACIAL EXPRESSIONS
FACIAL EXPRESSIONS, like body language, are a form of nonverbal communication.
Movement of the human face is controlled by two cranial nerves:
1) the TRIGEMINAL NERVE (cranial nerve 5) controls the deeper facial muscles attached to the bones of the head that are responsible for chewing food and speaking.
2) the FACIAL NERVE (cranial nerve 7) controls the superficial muscles attached to the skin, which are primarily responsible for facial expressions. The 5 branches of the facial nerve originate from the FACIAL NUCLEUS of the PONS. The UPPER THIRD of the face receives input from both the ipsilateral and contralateral facial nerves, whereas the LOWER TWO THIRDS of the face are controlled primarily by contralateral facial nerves.
Facial expression can be voluntary or spontaneous:
1) VOLUNTARY facial expressions are controlled by primary motor cortex. People with VOLITIONAL FACIAL PARESIS are unable to smile on command on the side of the mouth contralateral to their damage. However, when their laugh is spontaneous, they can show spontaneous smiling on the otherwise paralyzed side of the face.
2) SPONTANEOUS facial expressions are controlled by subcortical structures. Parkinson’s disease, which involves subcortical motor structures, lose the ability to smile spontaneously while retaining the ability to smile on command.
the BIOLOGICAL CORRELATES of EMOTION
Several studies point to a BIOLOGICAL PREDISPOSITIONS to emotions:
1) many emotional expressions appear to be viewed similarly across human cultures;
2) monkeys raised in isolation still show fear of pictures of other monkeys engaged in threatening behaviors;
3) monozygotic twins are more similar than dizygotic twins in the age at which they begin to show fear of strangers.
Emotional states are accompanied by interacting physical responses that usually combine activation of 6 elements:
1) the AUTONOMIC NERVOUS SYSTEM;
2) the AMYGDALA;
3) the INSULA;
4) the ANTERIOR CINGULATE CORTEX;
5) the BASAL GANGLIA;
6) the CEREBRAL CORTEX
the AUTONOMIC NERVOUS SYSTEM and EMOTION
The AUTONOMIC NERVOUS SYSTEM - and in particular its SYMPATHETIC division - participates in the GENERAL AROUSAL associated with emotional states. It is controlled by the HYPOTHALAMUS, either directly or by way of the NUCLEUS of the SOLITARY TRACT, a structure located in the MEDULLA that receives input from the hypothalamus and acts on the ANS.
the AMYGDALA, the INSULA and EMOTION
The AMYGDALA and the INSULA are associated with the identification of emotional stimuli and the arousal resulting from that identification.
The AMYGDALA’s primary role is to process unexpected, unusual stimuli, especially those that might be important to safety and survival. Its role has been studied in subjects in which structure was damaged:
- KLUVER-BUCY SYNDROME - originally studied in monkeys - results from damage to the temporal lobes, and the amygdala in particular. It produces reduced emotionality, especially in response to fear-producing stimuli;
- Rats with damaged amygdalas are immune to CLASSIC CONDITIONING - they fail to learn to fear a tone that reliably predicts the onset of electric shock;
- In a clinic case study, a patient whose amygdalas were destroyed was able to effectively recognize all emotions but fear - damage to the amygdala affects the PROCESSING of FACES.
The INSULA participates in making the distinction between positive and negative stimuli - POSITIVE feelings are associated with activity in the ROSTRAL areas of the insula and NEGATIVE feelings with the more CAUDAL areas.
A coordinate role of these structures could be that the amygdala initiates arousal, especially in response to negative stimuli, while the insula helps us discriminate between positive and negative stimuli.
the ANTERIOR CINGULATE CORTEX and EMOTION
The ANTERIOR CINGULATE CORTEX:
1) participates in the conscious cognitive appraisals of threat;
2) serves as a major gateway between the amygdala, other limbic structures, and the frontal lobes of the cerebral cortex;
3) processes information about physical PAIN;
4) cooperates with the ORBITOFRONTAL CORTEX in the INHIBITION of AGGRESSION.
the BASAL GANGLIA and EMOTION
The BASAL GANGLIA participate in voluntary MOVEMENT in general, including the coordination of movement in response to emotional stimuli. Observing facial expressions of disgust produces considerable activity in the basal ganglia.
the CEREBRAL CORTEX and EMOTION
FRONTAL LOBE DAMAGE produces emotional disturbance. This was first discovered in a lesion study in monkeys: researchers removed the frontal lobes from two chimpanzees and reported that the chimpanzees became much calmer. This led to the widespread use of LOBOTOMY - the surgical separation of the frontal lobes from the rest of the brain - for problems ranging from schizophrenia to depression to anxiety.
Emotionality seems to show hemisphere LATERALISATION:
- the LEFT HEMISPHERE is associated with approach of positive stimuli, and anesthetizing it results in feelings of depression;
- the RIGHT HEMISPHERE is associated with avoidance of negative stimulus, and anesthetizing it results in apparent happiness. It plays a greater role than the left in processing emotion for most people; this is why the left side of the face - and especially its lower two thirds, controlled contralaterally by the right hemisphere - is more expressive.
EMOTION REGULATION
EMOTION REGULATION is the control of the experience and the expression of emotions - it is not static over the lifetime: older adults, compared to younger adults, show a stronger preference for attending to positive information and ignoring negative information, which might contribute to lower rates of major depressive disorder with age.
THEORY OF MIND
THEORY OF MIND is the ability to understand another person’s point of view - it is central to human social life and it allows us to interpret, predict, and even manipulate others’ behavior. It involves activity in the ORBITOFRONTAL CORTEX, thus it is not believed to be present at 3 years of age but emerges at 4 or 5 years, when such cortex has developed.
LIE DETECTION
POLYGRAPH tests collect physical arousal data, such as respiration, galvanic skin response and blood pressure. The interviewer first asks basic, unimportant questions - from which the baseline level is recorded - followed by questions to which the interviewed might lie. The data is then confronted to the baseline level, and any difference reflects arousal and thus, deception.
Polygraph tests are widely used by both law enforcement and employers, in spite of their empirical unreliability - polygraph data reflect arousal, and an innocent person might be aroused out of fear of being accused. Furthermore, the general lack of arousal often found in antisocial people, along with their failure to see lying as morally wrong, allows many guilty people to appear innocent.
Laboratory studies have shown that deception can be detected using fMRI in law-abiding participants, as opposed to real criminals, who are lying about simple, concrete tasks.
