Psychology- Chapter 10: Motivation and Emotion
Motivation involves goal-directed behaviour.
Organisms seek to maintain homeostasis, a state of
physiological equilibrium or stability.
A drive is an internal state of tension that motivates an
organism to engage in activities that should reduce this
When individuals experience a drive, theyre motivated to
pursue actions that will lead to drive reduction.
An incentive is an external goal that has the capacity to
motivated behaviour. Ex. Ice cream, steak, approval from
friends, an A on an exam, etc.
Drive and incentive models of motivation are often contrasted
as push versus pull theories.
Drive theories emphasize how internal states of tension push
people in certain directions.
Incentive theories emphasize how external stimuli pull people
in certain directions.
According to drive theories, the source of motivation lies
within the organism. And with incentive theories, the source
of motivation lies outside the organism, in the environment.
Expectancy-value models of motivation are incentive theories
that take this reality into account. Ones motivation to
pursue a particular course of action will depend on two
(1) Expectancy about ones chances of attaining the incentive
and (2) the value of the desired incentive.
Thus, your motivation to pursue a promotion at work will
depend on your estimate of the likelihood that you can snare
the promotion (expectancy) and on how appealing the promotion
is to you (value).
Psychologists who take an evolutionary perspective say
dominance provides a reproductive or survival advantage.
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, including (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, and (4) dominant
males may acquire more material resources, which may increase
The Range and Diversity of Human Motives
Most theories (evolutionary theories being a notable
exception) distinguish between biological motives that
originate in bodily needs, such as hunger, and social motives that originate in social experiences, such as the need for
Motivation of Hunger and Eating
Biological Factors in the Regulation of Hunger
There is an association between stomach contractions and the
experience of hunger. Cannon theorized that stomach
contractions cause hunger. This theory was eventually
Theories of hunger focus on (1) the role of the brain, (2)
blood sugar level, and (3) hormones.
The hypothalamus is a tiny structure involved in the
regulation of a variety of biological needs related to
The lateral (LH) and ventromedial (VMH) areas of the
hypothalamus are elements in the neural circuitry that
regulates hunger but are not the key elements and are not
simple on-off centres.
Today scientists believe that another area of the
hypothalamusthe paraventricular nucleus (PVN)plays a larger
role in the modulation of hunger.
Contemporary theories of hunger focus more on neural circuits
that pass through areas of the hypothalamus rather than on
anatomical centres in the brain.
Ghrelin performs double duty as neurotransmitter in the
nervous system and as a hormone in the endocrine system.
Elevated ghrelin levels are associated with increased food
Glucose and Digestive Regulation
Glucose is a simple sugar that is an important source of
Glucostatic theory proposed that fluctuations in blood glucose
level are monitored in the brain by glucostatsneurons
sensitive to glucose in the surrounding fluid.
Some researchers continue to believe that glucostatic
mechanisms contribute to the modulation of eating.
The vagus nerve carries information about the stretching of
the stomach walls that indicates when the stomach is full.
Insulin is a hormone secreted by the pancreas. It must be
present for cells to extract glucose from the blood.
Insulin secretions play a role in the fluctuation of hunger.
Leptin is produced by fat cells throughout the body and
released into the bloodstream.
Leptin circulates through the bloodstream and ultimately
provides the hypothalamus with information about the bodys
fat stores. Leptin apparently activates receptors in the brain that
inhibit the release of neuropeptide Y, which leads to activity
in the paraventricular nucleus of the hypothalamus, which
Environmental Factors in Hunger
Three key environmental factors are (1) the availability of
food, (2) learned preferences and habits, and (3) stress.
Food Availability and Related Cues
Some theorists emphasize the incentive value of food and
argue that humans and other animals are often motivated to
eat not by the need to compensate for energy but by the
anticipated pleasure of eating.
According to this perspective, the availability and
palatability of food are the key factors in regulating
The presence of tasty food often leads people to eat even
though they are already quite full from recently consumed
Research shows that hunger is influenced by food availability
As you eat a specific food, its incentive value declines.
This phenomenon is called sensory-specific satiety.
If only a few foods are available, the appeal of all of them
can decline quickly. But if many food are available, people