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Lecture 5

Lecture 5 - Physiological Mechanisms of Arousal & Theories of Emotion

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York University
PSYC 2230
Frank Marchese

Chapter 4: Physiological Mechanisms of Arousal and P. 367-378: Theories of Emotion 1. Theory and research to explain motivation in terms of arousal mechanisms in the nervous system a. Earliest formulations of arousal began with the James-Lange theory of emotion (p. 371). Theory states that emotion follows changes in bodily response which follows the perception of an emotion arousing stimulus. Emotion and motivation come into combination: when one it motivated, one is emotional. i. S  Bodily Responses  Psychological Emotion  Action (fight/flight) ii. It is the bodily Rs that are “fed-back” to the brain that indicate a “changed state” (arousal). Perception of “changed state” leads to experience of emotion and resulting action (ANS – autonomic nervous system) iii. ANS = a set of nerves outside the brain iv. <1884: We perceive the stimulus  emotional reaction  motivates us to behave v. James-Lange Theory: perception  bodily changes  emotion  behaviour 1. Body changes serve as the basis of the emotion vi. Cannon’s Emergency Theory: perception  bodily changes/emotion  behaviour vii. Schachter’s Cognitive-Physiological Model: perception  bodily changes/cognitive label  emotion  behaviour viii. Zeitgeist = Zeit (time) geist (spirit) – spirit of the time (James and Lange coming to a similar idea of emotion independently) b. Cannon-Bard Emergency theory of emotion. Emotions result from the activation of the thalamus by external sensory information from the environment. This sensory information is relayed to the cortex. The cortex then releases this thalamus to trigger emotional responses. (CNS – central nervous system) i. CNS = emphasis on central nervous system, nerves within the brain ii. Cortex, thalamus, hypothalamus iii. Hypothalamus mediates much of our emotional life (p. 72) iv. S  Thalamic Activation  Cortical Activation  Release of Thalamus to Trigger  Emotional Responses  Actions c. Schachter’s cognitive-physiological theory of emotion. Subjective feelings of emotion require both physiological arousal plus a cognitive label that attributes the aroused state to particular causes (internal/external locus of causation) i. Am I sad because of something I am remembering (internal) or feeling sad because of something I am witnessing in the environment (external) ii. We need some kind of information/cues to label our state of arousal iii. Stimulus  Arousal Plus Cognitive Label  Emotion  Action 2. Arousal theory: how does organism become activated? a. See emotion and motivation on a continuum from low levels of arousal to high levels of arousal (see figure 4.1, 4.2 p. 70) i. Behaviour changes as a result of arousal ii. As arousal increases behaviour efficiency increases (more alert = more aware = more efficient) iii. There is an optimal level of arousal where behaviour is more efficient (low arousal = less aware/efficient) Overaroused causes confusion (we don’t know what to do first) iv. The inverted U function reveals this as the Yerkes-Dodson Law (Figure 4.2 p. 70) v. Relationship between arousal level and efficiency depends on both arousal level and task- complexity, with high arousal being optimal for simple tasks, and lower arousal for complex tasks vi. Degree of arousal is low/high = comma  sleep  waking  alert  stress b. Brain structures and arousal: i. In CNS, if a cut is made between the medulla and spinal cord, animal still goes through sleep-wake cycle. (pons and RAS reticular activating system are kept intact, essential for organism to go through normal sleep/wake cycle). However, if cut is between the pons and the RAS, animal constantly sleeps. 1. If cut pons and RAS, you are delimiting the arousal 2. Crucial structures in brain which control our ability to be awake/sleep ii. RAS: Moruzzi and Magoun showed that the RAS located in the brain stem’s central core which runs from the medulla to the thalamus when stimulated leads to changes in the cortex, as if the cortex were being exposed to normal sensory stimulation from the external environment 1. If stimulates RAS, it awakens the brain (cortical arousal: process info) 2. EEG recording show changes in electrical activity of brain a. Alpha waves (large, slow waves) when brain is at rest (reduced arousal) b. BETA waves (small, fast waves) when brain is alert/aroused c. Stimulation of RAS leads to beta wave activity (arousal), RAS receives sensory input from external sensory systems, from muscles and internal organs, and from the cortex d. Lindsley cut all structures around the RAS and the organism still showed normal sleep-wake cycle. Cut RAS and organism goes to sleep e. RAS sends fibers to cortex and is responsible for arousing it (alertness) f. Emotion and motivation are equivalent to cortical arousal c. Hebb’s theory: Motivation is activation of RAS. This is done in 2 ways: 1. Sensory input has an arousal function on the cortex; and 2. A cue function to provide information when organism is aroused; the cue function of stimulus is effective because organism can appreciate the information coming in (p. 73) i. Sensory stimulation is sent to RAS and the cortex via the thalamus. Sensory stimulation to the RAS “tones-up” the cortex, and thus the cortex is ready to handle the input that is coming from the thalamus (relay station—sends information to appropriate cortical areas) ii. Cortex sends fibers down to RAS and can arouse or inhibit it d. Sleep and motivation: (p. 70 figure 4.1) i. Sleep is a low state of arousal ii. Sleep consists of several stages 1. Alpha wave activity in relaxed state replaced by… (beta waves: small and fast) 2. Stage 1: Fast, low amplitude waves for 15 minutes (theta wave) 3. Stage 2: sleep spindles – slower and larger waves for 15 mins 4. Stage 3: More slower and larger waves for 15 mins (delta waves) 5. Stage 4: Slow, high amplitude waves for 30-45 mins (delta waves) 6. Stage 5: REM sleep – low amplitude, fast waves (BETA waves) from several minutes to one hour – dreaming occurs (paradoxical sleep) iii. 1/3 of our lives spent in sleep iv. Sleep results from more than fatigue (rhythms of the body for restoring) v. Sleep corresponds to circadian rhythms and may protect u
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