Chapter 11: Emotions, Aggression, & Stress

Made by @agreyr

Emotion

A subjective experience accompanied by distinctive cognition, behavior, and physiological changes

Must be experienced in the body; involves characteristics of valence and arousal

Examples of high arousal, positive valence emotions

Excited, astonished, aroused, delighted, glad, happy

Examples of low arousal, positive valence emotions

Pleased, satisfied, content, serene, calm, at ease, relaxed, sleepy

Examples of high arousal, negative valence emotions

Alarmed, afraid, angry, tense, distressed, annoyed, frustrated

Examples of low arousal, negative valence emotions

Miserable, depressed, sad, bored, gloomy, droopy, tired

Emotion theories

All theories of emotion involve a stimulus, a physiological state, and an emotional experience; the difference lies in which comes first (informs cause and effect)

James-Lange theory, Cannon-Bard theory, Schacter & Singer two factor theory

James-Lange theory of emotion

The stimulus first triggers a physiological response in the body which in turn triggers the emotional experience in the brain; the rapid heartbeat produces the fear

Cannon-Bard theory of emotion

The stimulus simultaneously triggers the physiological response in the body and triggers the emotional experience in the brain; they are parallel processes

Schacter & Singer two factor theory of emotion

Emotions are based on inferences about the causes of general physiological reactions; it has to involve a cognitive appraisal of the current context

Evolution of emotions - Charles Darwin

Emotional expressions are the product of evolution and should be studied across species; human and nonhuman animals show comparable (though often subtle) emotion with universal meanings

Emotional expressions signal what the animal is likely to do next; if emotional signals are beneficial, they will evolve to more effectively communicate

Principle of antithesis

Opposite messages signaled by opposite movements and postures

Are emotions universal?

Likely 6-8 core emotions, consistent across time and culture

People of different cultures make similar expressions; can identify emotions of others, despite different cultures

Paul Ekman & colleagues core emotions

Anger, sadness, happiness, fear, disgust, surprise, contempt, embarassment

Facial feedback

Facial expressions are mediated by muscles, cranial nerves, and CNS pathways

Facial expressions of emotion can be faked; microexpressions can reveal true feelings, and different muscles are involved in real vs fake smiles

Microexpressions

Ultra-brief facial expressions that reveal true feelings by breaking through fake ones

Muscles involved in fake vs real smiles

Orbicularis oculi (Duchenne/genuine) & Zygomaticus major (both)

Facial feedback hypothesis

Voluntarily controlling muscles can influence our emotional experience

Amygdala

Threat detection/appraisal

Responsible for the evaluation of emotion-relevant aspects of a stimulus

Limbic system

Maintain amygdala response or dial it back

Processes higher order information and monitors appropriate amygdala activation

How the system works

Low Road: eye —> thalamus —> amygdala

High Road: eye —> thalamus —> cortex —> amygdala

Evidence for brain regions

Klüver-Bucy Syndrome, Urbach-Wiethe Disease, Sham Rage, fear conditioning

Klüver-Bucy Syndrome

Bilateral amygdala damage causes emotional changes including a reduction of fear and anxiety; initially found in monkeys

Urbach-Wiethe Disease

Calcification of the amygdala leads to the inability to recognize expressions of fear and danger; also a lack of fear

Sham Rage

Cats and dogs with their cortex removed show extreme and unfocused aggressive responses; hypothalamus must remain intact when cortex is removed

Fear conditioning

Establishment of fear response to a previously neutral stimulus (tone); the tone alone comes to elicit freezing and enhanced startle

Aggression

Behavior intended to cause pain or harm

Hormonal contributions to aggression

Androgens seem to increase aggression in animals but story is more complicated in humans

Brain regions involved in aggression

Amygdala & ventromedial hypothalamus

Stress

The physiological changes that result when the body is exposed to harm or threat

Stressor

The experience that induces the stress response (bear, shock, exam, etc.); elicits the same response pattern whether psychological or physical stress

Stress pathways

Sympathetic nervous system (fight or flight, epinephrine) & HPA axis (stress hormone system, cortisol)

Hypothalamic-pituitary-adrenal (HPA) axis

Hypothalamus: Corticotropin Releasing Factor

Pituitary (anterior): Adrenocorticotropic Hormone

Adrenal gland: Cortisol

Hans Selye & stress research

Canadian physician who studied “ovarian extract” - injected rats daily with estrogen or control (saline) to investigate effects on stress

Results: ALL rats developed ulcers, enlarged adrenal glands, and shrinkage of the lymph nodes (stress response to injections)

Generalized Adaptation Syndrome

Three stage physiological stress response that appears regardless of the stressor that is encountered

Phase 1: Alarm reaction (mobilize resources)

Phase 2: Resistance (cope with stressor)

Phase 3: Exhaustion (reserves depleted)

Psychoneuroimmunology

Study of the interaction of psychological factors, the nervous system, and the immune system; includes biological factors

Stress and immune function

Acute stressors improve immune function; chronic stressors impair immune function

Brief stressors activate an inflammatory response (increased cytokines, peptide hormones that cause inflammation and fever)