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Chapter 7

CHAPTER 7 NOTES - Motivation

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PSYC 2230
Frank Marchese

CHAPTER 7: HEDONISM AND SENSORY STIMULATION HEDONISM •Troland believed that the nervous system is specially tuned to pleasurable and aversive events •He divided the information into 3 categories: a. Beneception occurs when pleasant feelings are aroused by stimuli b. Nociception occurs as the result of stimuli that arouse unpleasant feelings c. Neutroception exists when stimuli cause neither pleasant nor unpleasant feelings •Troland believed that sensations can be classified in one of these three categories •Vision, audition, cutaneous touch, and kinesthesis were considered neutroceptive • The hedonic value of an object in the environment is closely tied to the sensory qualities it possesses and the effect those stimuli have on the nervous system in terms of beneception, nociception, or neutroception •Beebe-center suggested that pleasantness and unpleasantness exist as opposite extremes on a hedonic continuum •Reactions of the sense organs react to stimulation (called bright pressure) produce pleasant feelings, while reactions of a different type (called dull pressure) produce unpleasant feelings •Beebe-center believed that instructions alter the pleasantness of stimuli by changing the actions of the sense organs rather than by altering perception of the stimulation at some more central (brain) level •The effects of instructions are more central in nature P.T. YOUNG: SIGN, INTENSITY, AND DURATION •Paul Thomas Young is perhaps the best known hedonic theorist •Center that exists a continuum with maximum negative affect (unpleasant or aversive stimuli) at one end and maximum positive affect (pleasant stimuli) at the other end •According to Young, the affective processes represented by this continuum have three properties: 1. Sign • Positive affect is associated with approach behaviour • Negative affect is associated with avoidance behaviour • We can determine the sign of a particular event by observing whether the organism approaches (+) or avoids (-) • Ex. Rats will approach and drink sweet-tasting fluids but will avoid (after initial contact) a bitter-tasting solution 2. Intensity • Affective processes also differ in intensity • To observe affective intensity differences of various substances, researchers usually employ preference tests • In a two-choice situation, the chosen substance is considered to be hedonically more intense than the nonchosen one • One might, for ex. Compare different solutions of sugar water • If the concentration of sugar in the water is different in the two bottles, a rat will prefer the more highly concentrated solution • Though the use of preference tests, we can chart hedonic intensity 3. Duration CHAPTER 7 page 1 • Some hedonic processes may last only as long as sensory stimulation lasts, while others presumably outlast the stimulation SENSORY STIMULATION AND THE HEDONIC CONTINUUM •Sensory stimuli provide information to an organism about the conditions of its external and internal environment •Affective processes, convey little information other than whether something is "good" (pleasant) or "bad" (unpleasant), and in a choice situation, "better than" or "worse than" •The hedonic continuum is not equivalent to sensory stimulation •This differnce is most appearant when one compares the realtionship of changes in hedonic intensity •We cannot assume that changes in sensory intensity will initiate similar changes in hedonic affect •The hedonic processes represented by the hedonic continuum have motivational influences on behaviour o First, positive affect is closely associated with approach behaviour and negative affect with withdrawal o Second, Young believed that affective processes both activate and direct behaviour so that maximum positive affect and minimum negative affect are maintained o Third, affective processes lead to the development of stable motives and dispositions •Changes in motivation are also seen as dependent on changes in hedonic value o If a rat is given the choice between flour and sugar, it will prefer sugar o If one of those is replaced by a new food, an abrupt change may occur in the behaviour exhibited toward the old substance in the choice situation o This suggests that introduction of the new substance has altered the motivation of the organism •Young believed that the changes in motivation observed when a novel food is introduced occur because the organism has developed an expectancy of choice between two substances of different hedonic value • This expectancy is the result of hedonic feedback from the previous sampling of the substances: the organism samples the substances it may choose between and develops a preference for one of them based on the hedonic value of each •Changes in goal objects lead to change in expectancy, which in turn alter performance CHAPTER 7 page 2 THE MOTIVATIONAL INFLUENCE OF SENSATIONS • Carl Pfaffmann conducted much research on the physiological mechanisms of taste, and his work seemed to agree with Young's ideas • He suggested that sensory stimulation by itself is motivating and leads to approach or withdrawal behaviour • Taste sensations are sufficient to trigger approach or avoidance behaviour without having to be tied to any physiological change • Hedonic intensity ad sensory intensity are not equivalent • Recording the electrical activity of chorda tympani (a cranial nerve sending taste information to the brain), he showed that as salt concentration in a fluid increases so does the electrical activity of the nerve • Hedonic value at first increases and then decreases as salt concentration becomes greater • Pfaffman believed that the stimulus properties of a tasted substance directly determine the hedonic value of the substance HEDONIC VALUE AND CONTACT RECEPTORS • The stimulation of contact receptors (such as taste) seems much more often associated with strong emotion than is the stimulation of distance receptors (ex. Vision) • Contact receptors are also much more often associated with consummatory activity (taste-eating, genital-intercourse) • the hedonic tone provided directly by contact receptors may be an evolutionary adaptation CHAPTER 7 page 3 • Ex. Distance receptors (vision) give some lead time for one to make a judgement and react, but contact receptors often involve stimuli (such as pain) that require a reaction if the organism is to survive • Hedonic value (pleasure or pain) may therefore had evolved in conjunction with stimulation of the contact receptors to quickly direct behaviour PAIN • Pain is useful because it tells us we have been injured and often causes us to alter our behaviour so that the injured part of our body has time to heal • Pain can also seem out of proportion to the size of the injury • Consider the phenomenon of phantom limb pain, where excruciating pain may be experienced even though the involved body part has been amputated • In these cases, pain does not seem very adaptive and may in fact interfere with more adaptive behaviours • One of the foremost researchers in the study of pain is Ronald Melzack, who proposed the theory of pain that is still influential today • Ex. 65% of men wounded in battle feel no pain when brought to the combat hospital, yet approximately, 80% of civilians with such injuries report severe pain and ask for pain medication • No simple and direct relationship existed between the severity of an injury and the amount of pain experienced • Pathological pain states such as causalgia (a severe burning pain that is sometimes caused by a partial lesion of a peripheral nerve), peripheral neuralgia (which can occur following peripheral nerve infection) and the previously mentioned phantom limb pain are often unsuccessfully treated by surgical lesions of either the peripheral or nervous system • Melzack pointed out that if a person's attention is focused on the painful aspects of a procedure, pain is often experienced more intensely • Melzack and Wall proposed a model of pain that emphasized the role of higher brain prices in controlling the experience of pain and a modulating system within the spinal cord that influenced how much pain information reached the brain o This model was called the gate control theory • Research since the original publication of the gate control theory has shown that the pain control gates are modulated by neurotransmitter changes involving the endogenous opiates and perhaps other factors as well • Further evidence for the role of an opioid system in the gating of pain is suggested by studies that show that naloxone, which blocks the effects of opiates, also blocks analgesic effects of acupuncture • Studies show that women have a greater pain sensitivity than men • The gender differences in pain are from a number of factors, including genetics, hormonal differences, differing gender roles , and other psychosocial factors • Learning and emotional reactions and even placebos can modulate pain as well • In particular portions of the thalamus, limbic system, prefrontal cortex, somatosensory cortex (both primary and secondary), and cingulate cortex are involved with the perception of pain • Recently, the basal ganglia have been show to play a role in pain too CHAPTER 7 page 4 • In addition, the periaqueductal gray matter in the brain stem appears to be important in the reduction of pain produced by the endogenous opiates •This area, through connections to the nucleus raphe magnus in the medulla and from there to the dorsal horn of the spinal cord, may also influence the perception of pain at the level of the spinal cord •The endogenous opiates appear to produce analgesia by blocking the production of a transmitter known as substance P as shown in figure 7.3 •The central modulation of pain, seems to be mediated at least in part, by the action of endogenous opiates NOVELTY, CURIOSITY, AND EXPLORATORY •A group of studies performed indicated that external stimuli can serve to motivate behaviour directly •Cofer and Appley noted that studies on thee sensory stimulation and motivation could be grouped into studies indicating that behaviours are released by stimulation and studies indicating a need for stimulation BEHAVIOURS RELEASED BY STIMULATION •Harry Harlow studied primate behaviour extensively •He pointed out that external stimuli are important in motivating behaviour and that much of human behaviour is motivated by such nonhomeostatic mechanisms CHAPTER 7 page 5 •Berlyne suggested that factors such as novelty and uncertainty have motivational properties because they increase the arousal level of the organism •He argued that we maintain an optimal level of arousal •If stimulation drops too low (boredom) we become motivated to increase our arousal level •On the other hand, if arousal becomes too high, we will be motivated to lower it •Thus novel or surprising stimuli will motivate behaviour directed toward themselves if they provide a small change in arousal, because small changes in arousal are pleasant •Montgomery also studied exploratory behaviour •He allowed rats to explore one of three mazes, that were painted black, white, and gray o Each rat was allowed to explore the maze twice, and the amount of time spent in exploring the second time was related to the colour (rats are colourblind, they're perception would have been based on grayscale differences) of the first maze explored o He found that maximum exploration occurred when the second maze was maximally different from the first (black first, white second; white first, black second) and that least exploration occurred when the second maze was identical to the first (white first, white second; black first, black second) o Intermediate amounts occurred when the stimulus change from first to second maze was intermediate (white to gray; black to gray) o Thus, the amount of exploratory behaviour shown by the rats seemed controlled by the degree of stimulus change involved o Stimulus change (novelty) motivates behaviours such as exploration •Donald Hebb believed that moderate changes in arousal are reinforcing •Play behaviour seen in many organisms, occurs when other needs are not active •Play behaviour often seems to occur as the result of boredom and serves to provide a higher level of arousal •Depriving an organism of changing stimulus input (either by eliminating it or by making stimulation unchanging) should lead to motivated behaviour THE NEED FOR STIMULATION •Some studies have attempted to reduce the absolute value of stimulation to very low levels, while others have examined the effects of reduction in the patterning of stimulation •Some studies have examined the roles of monotonous or unchanging environments •These studies are collectively called "Sensory Deprivation Experiments" o The effects of sensory deprivation have been researched in developing organisms as well as in adults o Results of both types of studies generally indicate a disruption of normal behaviour Early Sensory Deprivation: •Thompson and Melzack studied the effects of sensory restriction on the development of Scottish terriers •They were divided into two groups: one group was raised normally and served as a control for the second group; second group were each raised in individual cages and served as the experimental group CHAPTER 7 page 6 • When the experimental group were let of their isolation condition they were extremely active and playful • The isolated group explored more in maze tests than the controls, even several years after release from isolation and exhibited higher activity levels • Thus, sensory restriction apparently altered the normal motivational behavior of the dogs • In another part of the experiment, the two groups were tested for their reactions to both strange and painful objects • The control group learned to avoid the strange object by running away • The experimental group became highly agitated by it, but did not avoid it • Sensory restriction had long-lasting (and permanent) effects on the behaviour of the isolated Scotties • Though not appearing unmotivated, the isolates seemed hyperexcitable and unable to direct their behaviour in an efficient, adaptive manner • The studies of cats, monkeys, and chimpanzees, reported very similar effects (by Riesen) • Riesen noted that exposure of cats raised in dark cages to a normal-lighted environment revealed perceptual deficits and violent emotionality • The dark-reared animals showed: 1. Hyperexcitability 2. Increased incidences of convulsive disorders 3. Localized motor impairment • He reported that the increases in stimulation were emotion producing for his dark-reared subjects • Research on sensory restriction indicates that adequate stimulation is necessary for normal development • New sensations, to a deprived animal, lead to fear and withdrawal ATTACHMENT Maternal Deprivation: • T
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