Chapter 10: Motivation and Emotion
Motivational Theories and Concepts
• motives are the needs,wants,interests, and desires that propel people in certain directions.
motivation involves goal-directed behaviour.
goals and our motivation to achieve them are often important characteristics of successful adjustment.
1. Drive Theories:
• drive theories apply the concept of homeostasis to behaviour
drive - an internal state of tension that motivates an organism to engage in activities that should reduce this
• unpleasant states of tension are viewed as disruptions of the preferred equilibrium.
• according to drive theories, when individuals experience a drive,they’re motivated to pursue actions that will
lead to drive reduction.
• drive theories cannot explain all motivation because:
homeostasis appears irrelevant to some human motives,such as a “thirst for knowledge.”
• motivation may exist without drive arousal (ex. you might get popcorn at the movies after seeing an
advertisement even though you are not hungry).
2. Incentive Theories:
• propose that external stimuli regulate motivational states
incentive - an external goal that has the capacity to motivate behaviour. (ex. ice cream,approval,prize)
• drive and incentive models of motivation are often contrasted as push vs. pull theories
• drive theories emphasize how internal states of tension push people in certain directions(motivation is
within an organism).
• incentive theories emphasize how external stimuli pull people in certain directions(motivation lies outside
• incentive theories emphasize environmental factors and downplay the biological bases of human motivation.
• expectancy-value model of motivation state that one’s motivation to pursue a particular course of action will
depend on 2 factors: 1. expectancy about one’s chances of attaining the incentive
2. the value of the desired incentive.
3. Evolutionary Theories:
psychologists who take an evolutionary perspective argue that natural selection favours behaviours that
maximize reproductive success.
• they also argue that dominance is a crucial motive for a species
• evolutionary analyses of motivation are based on the premise that motives can be best understood in terms of
the adaptive problems they have solved for our hunter-gatherer ancestors.
•the need for dominance is thought to be greater in men than women because it could facilitate males’
reproductive success in a variety of ways:
1. females may prefer mating with dominant males
2.dominant males may poach females from subordinate males
3.dominant males may intimidate male rivals in competition for sexual access
4.dominant males may acquire more material resources,which increase mating opportunities.
• achievement,power(dominance),and intimacy are among most heavily studied social motives
4. The Range and Diversity of Human Motives:
• most theories distinguish b/w biological motives and social motives
people have limited number of biological motives
• people share the same biological motives, but their social motives vary,depending on their experiences.
Biological Motives in Humans Social Motives in Humans
• hunger • achievement(need to excel)
• thirst • afﬁliation(need for social bonds)
• sex • autonomy(need for independence)
• temperature • nurturance(need to nourish and protect others)
• excretion • dominance(need to inﬂuence or control others)
• sleep • exhibition(need to make an impression on others)
• activity • order(need for orderliness,tidiness,organization)
• aggression •play(need for fun,relaxation,amusement)
The Motivation of Hunger and Eating
1. Biological Factors in the Regulation of Hunger: a) Brain regulation:
• the experience of hunger is controlled in two centres located in the hypothalamus
• when the lateral hypothalamus(LH) is lesioned in animals, they show little or no interest in eating, as if their
hunger centre has been destroyed.
• when the ventromedial nucleus of the hypothalamus(VNH) is lesioned in animals,they eat excessively and
gain weight rapidly, as if their ability to recognize safety has been destroyed.
• therefore, the LH and the VNH were recognized as the brain’s on-oﬀ switches for the control of hunger
• the current thinking is that the LH and the VNH are elements in the neural circuity that regulates hunger but
are not the key elements and are not simple on-oﬀ centres.
• today,scientists believe that the paraventricular nucleus(PVN) plays a larger role in the modulation of hunger
because this area contains a group of neurons that are sensitive to incoming hunger signals and another
groups of neurons that respond to satiety signals.
contemporary theories of hunger focus more on neural circuits that pass through areas of the hypothalamus,
which depend on a variety of neurotransmitters.
• some neurotransmitters that play a major role are: neuropeptide Y, serotonin, GABA, ghrelin, and orexins.
• ghrelin plays a role as a neurotransmitter and as a hormone; it plays a role in stimulating hunger; increased
levels are associated with increased food intake.
a) Glucose and digestive regulation:
• manipulations that decrease blood glucose level can increase hunger
• manipulations that increase blood glucose level can make people feel satiated
• glucostatic theory proposed that ﬂuctuations in blood glucose level are monitored in the brain by glucostats
glucostats - neurons sensitive to glucose in the surrounding ﬂuid.
there are other mechanisms such as the cells in the stomach,which send signals to the brain that inhibit further
eating.(ex. the vagus nerve carry information about the stretching of the stomach).
b) Hormonal regulation:
• insulin is secreted by the pancreas and it has to be present for cells to extract glucose from the blood
• an inadequate supply of insulin is what causes diabetes
• the secretion of insulin is associated with increased hunger
• Judith Rodin(UofT) demonstrated that the mere sight and smell of enticing food can stimulate the secretion
• leptin is produced by fat cells throughout the body and released into the bloodstream
• higher levels of fat generate higher levels of leptin
• leptin circulates the bloodstream and provides the hypothalamus with information about the body’s fat stores. • when leptin levels are high,hunger diminishes.
• leptin activates receptors in the brain that inhibit the release of neuropeptide Y, which leads to activity in the
PVN of the hypothalamus,which inhibits eating.
2. Environmental Factors in the Regulation of Hunger:
a) Food availability and related cues:
• according to the perspective that we are often motivated to eat just for pleasure, the availability and
palatability of food are the key factors regulating hunger.
• the sensory-speciﬁc satiety phenomenon states that as you eat a speciﬁc food, its incentive value declines:
• Example: If only a few foods are available, their appeal can decline quickly. However, of many foods are
available, people can keep shifting to new foods and end up eating more overall.
hunger can also be triggered by exposure to environmental cues that have been associated with eating(ex. TV
commercials for delicious-looking food or seductive odours coming from the kitchen)
• the presence of others generally inhibits eating
b) Learned preferences and habits:
• people from diﬀerent cultures display diﬀerent patterns of food consumption
• humans do have some innate taste preferences of a general sort
• Example: a preference for sweet tastes is present at birth, and humans’ preference for high-fat foods
appears to be at least partly genetic in origin.
• taste preferences are partly a function of learning associations formed through classical conditioning.
• eating habits are also shaped by observational learning:
Example: young children are more likely to try an unfamiliar food if an adult tries it ﬁrst.
• repeated exposure to a new food often lead to increased liking.
c) Stress and eating:
• stress leads to an increased eating in many people
• some studies suggest that stress-induced eating may be especially common among chronic dieters.
• some theorists believe that it is stress-induced physiological arousal rather than stress itself that stimulates
• other researchers suspect that it is the negative emotions often evoked by stress that promote additional eating
3. Eating and Weight: The Roots of Obesity: body mass index(MBI) - an individual’s weight(in kilograms) divided by height(in meters) squared.
• a BMI over 30 is considered obese, while BMIs b/w 25 and 29.9 are considered overweight.
• obesity rates in Canada have doubled in the last 2 decades
• men are more likely to go from normal to overweight, however, women are more likely to from overweight to
• overweight people are more vulnerable than others to cardiovascular diseases,diabetes,hypertension,
respiratory problems,gallbladder disease,stroke,arthritis,and some types of cancer.
• evolutionary-oriented researchers point out that over the course of history,most animals and humans have
lived in environments in which there was ﬁerce competition for limited,unreliable food resources and where
starvation was a very real threat.Therefore, warm-blooded animals evolved a propensity to consume more
food than immediately necessary when the opportunity presented itself, because food might not be available
a) Genetic predisposition:
• researches found that adoptees resemble their biological parents much more than their adoptive parents.
• in twin studies, researchers found that identical twins reared apart were far more similar in BMI than
fraternal twins reared together.
b) Excessive eating and inadequate exercise:
• the high availability of high-fat,caloric food
• modern conveniences,such as cars and elevators, and changes in the world of work, such as the shift to more
lower-income families seem to be more vulnerable to inactivity
c) The concept of set point:
set-point theory - proposes that the body monitors fat-cell levels to keep them(and weight) fairly stable.
• when fat stores slip below a crucial set point, the body supposedly begins to compensate for this change,
which leads to increased hunger and decreased metabolism.
settling-point theory - proposes that weight tends to drift around the level at which the constellation of factors
that determine food consumption and energy expenditure achieves an equilibrium.
• according to this view, weight tends to remain stable as long as there are no durable changes in any of the
factors that inﬂuence it.
• the diﬀerences b/w set-point and settling-point are: • settling-point theory casts a much wider net than set-point theory, which attributes weight stability to very
speciﬁc physiological processes
• set-point theory asserts that an obese person’s body will initiate processes that actively defend an excessive
weight, whereas settling-point theory suggests that if an obese person makes long-term changes in eating
or exercise,that person’s settling point will drift downward without active resistance.
d) Dietary restraint:
• chronic dieters are restrained dieters - people who consciously work overtime to control their eating impulses
and who feel guilty when they fail
• to lose weight, restrained eaters go hungry much of the time, but they are constantly thinking about food.
However, when their cognitive control is disrupted, they become disinhibited and eat to excess.
• “I’ve already blown it,so I might as well enjoy as much as I want.”
dietary restraint is thought to lead to frequent overeating and thus contribute to obesity.
• dietary restraint also contributes to the tendency to overeat just before beginning a diet
e) Eating disorders:
• anorexia nervosa - a disorder in which (mostly) young women literally starve themselves, sometimes to death.
• bulimia nervosa - a disorder in which (mostly) young women alternate between binge eating and purging.
• anorexia increased in occurrence in the 1960s, while bulimia - in the 1970s
• since 1987, the rate of hospitalization for eating disorders has increased dramatically for young(under 15) and
older(15-24) females alike(up 34% and 29% respectively)
Sexual Motivation and Behaviour
1. Determinants of Sexual Desire:
• teens who have sexual intercourse by the age of 13 are more likely to have multiple sex partners than those who
• girls with weak self-concepts at 13 are more likely than those with strong self-concepts to engage in sex early.
• approximately 30% of people who have multiple partners do not use a condom
• sex without condom appears to increase with age
a) Hormonal regulation: estrogens - the principal class of gonadal hormones in females.
androgens - the principal class of gonadal hormones in males.
• the hypothalamus and the pituitary gland regulate those hormones.
• gonadal hormones regulate the sex drive in many animals
• evidence suggests that hormones do contribute to the modulation of sexual desire in humans
males who develop hypogonadism during adulthood exhibit abnormally low levels of androgens and reduced
• higher levels of testosterone correlate with higher rates of sexual activity in both males and females.
2. Evolutionary Analyses of Human Sexual Behaviour:
• Robert Trivers’ parental investment theory states that a species’ mating patterns depend on what each sex has
to invest - in terms of time,energy,and survival risk - to produce and nurture oﬀspring.
• according to Trivers, the sex that makes the smaller investment will compete for mating opportunities with
the sex that makes the larger investment, and the sex with the larger investment will tend to be more
discriminating in selecting its partners.
• in humans, males are thought to compete with other males for the relatively scarce and valuable “commodity”
of reproductive opportunities.
Biological Evolutionary Signiﬁcance Behavioural
Males Reproduction involves Maximize reproductive success More interest in uncommitted
minimal investment of time, by seeking more sexual partners sex,greater number of sex
energy, and risk. with high reproductive potential.partners over lifetime;look for