EXPLORING
PSYCHOLOGY
EIGHTH EDITION IN MODULES
David Myers
PowerPoint Slides
Aneeq Ahmad
Henderson State University
Worth Publishers, © 2011
Motivation
2
Basic Concepts and Hunger
Module 25
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Motivational Concepts
 Instincts and Evolutionary
Psychology
 Drives and Incentives
 Optimum Arousal
 A Hierarchy of Motives
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Hunger
 The Physiology of Hunger
 The Psychology of Hunger
 CLOSE-UP: Eating Disorders
 Obesity and Weight Control
 CLOSE-UP: Waist Management
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Motivation
Motivation is a need
or desire that energizes
behavior and directs it
towards a goal.
AP Photo/ Rocky Mountain News, Judy Walgren
Aron Ralston was
motivated to cut his
arm off in order to free
himself from a rock
that pinned him
down.
Aron Ralston
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Motivational Concepts
Four perspectives used to explain motivation
include the following:
1. Instinct Theory (replaced
by the evolutionary
perspective)
2. Drive-Reduction Theory
3. Arousal Theory
4. Hierarchy of Needs
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Instincts & Evolutionary Psychology
Instincts are complex behaviors that have fixed
patterns throughout different species and are not
learned (Tinbergen, 1951).
Tony Brandenburg/ Bruce Coleman, Inc.
© Ariel Skelley/ Masterfile
Where the woman builds different kinds of houses
the bird builds only one kind of nest.
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Drives and Incentives
When the instinct theory of motivation failed, it
was replaced by the drive-reduction theory. A
physiological need creates an aroused tension
state (a drive) that motivates an organism to
satisfy the need.
The physiological aim of drive reduction is
homeostasis – the maintenance of a balanced or
constant internal state.
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Incentive
Where our needs push, incentives (positive or
negative stimuli) pull us in reducing our drives.
When there is both a need and incentive we are
strongly driven. Therefore with each motive we
can ask, ““How is it pushed by our inborn
physiological needs and pulled by incentives in
the environment?”
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Optimum Arousal
Human motivation aims to seek optimum levels of
arousal, not to eliminate it. Young monkeys and
children are known to explore the environment in the
absence of a need-based drive.
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A Hierarchy of Motives
Abraham Maslow (1970)
suggested that certain
needs have priority over
others, known as a
hierarchy of needs.
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Hunger
Ancel Keys (1950) studied the effects of
semistarvation on male volunteers.
The men became food-obsessed, preoccupied
with their unfulfilled need.
This illustrates how motives can hijack our
consciousness. When we are hungry, thirsty, or
fatigued little else seems to matter.
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The Physiology of Hunger
Stomach contractions (pangs) send signals to
the brain making us aware of our hunger.
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The Physiology of Hunger
Tsang (1938) removed rat stomachs, connected the
esophagus to the small intestines, and the rats still
felt hungry (and ate food).
If hunger pangs are not the only trigger, what else
makes us hungry?
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Body Chemistry & the Brain
Levels of glucose in the blood are monitored by
receptors (neurons) in the stomach, liver, and
intestines. They send signals to the hypothalamus
in the brain.
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Body Chemistry and the Brain
The lateral hypothalamus (LH) brings on hunger
(stimulation). Destroy the LH, and the animal has
no interest in eating. The reduction of blood
glucose stimulates orexin in the LH, which leads
rats to eat ravenously.
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Body Chemistry and the Brain
The ventromedial hypothalamus (VMH)
depresses hunger (stimulation). Destroy the VMH,
and the animal eats excessively.
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The Appetite Hormones
The hypothalamus monitors a number of hormones that
are related to hunger.
Hormone
Orexin increase
Tissue
Response
Hypothalamus Increases hunger
Ghrelin increase Stomach
Increases hunger
Insulin increase
Pancreas
Increases hunger
Leptin increase
Fat cells
Decreases hunger
PPY increase
Digestive tract
Decreases hunger
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Body Chemistry and the Brain
Interaction of hormones and brain activity may help
explain the body’s set point – a particular stable weight.
Falling below normal weight signals this “weight
thermostat” increasing hunger and decreasing activity.
Heredity influences body type and set point and our
bodies also regulate by controlling food input and
energy output.
Reducing energy expenditure drops basal metabolic
rate – the rate of energy expenditure for maintaining
basic body functions when the body is at rest
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The Psychology of Hunger
There is more to hunger than just our
physiological state.
Part of knowing when to eat is our memory of
our last meal. As time passes we anticipate
eating and become hungry again.
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Taste Preference: Biology or Culture?
Body chemistry and environmental factors
influence not only when we feel hunger but what
we feel hungry for!
Victor Englebert
Richard Olsenius/ Black Star
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Hot Cultures like Hot Spices
Countries with hot climates use more bacteriainhibiting spices in meat dishes.
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Eating Disorders
Anorexia nervosa: A person (usually an adolescent female)
diets and becomes significantly underweight, but still feels
overweight.
Bulimia nervosa: Episodes of overeating, usually high-calorie
foods, followed by vomiting, using laxatives, fasting, or
excessive exercise.
Binge-eating disorder: Significant binge-eating episodes,
followed by distress, disgust, or guilt, but without the
compensatory purging, fasting, or excessive exercise
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Eating Disorders
What is behind the development of
an eating disorder?
Family: Families that put emphasis
on weight or high achievement.
Genetics: Eating disorders are more
likely to occur in identical twins
rather than fraternal twins.
Environment: Cultures that idealize
thinness and vilify “fattness”
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Obesity and Weight Control
Why do some people gain weight while eating
the same amount as someone who does not?
Is there weight-loss hope for the 66% of
American who are overweight according to the
CDC?
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Obesity and Weight Control
Our bodies have not yet caught up to our modern abundance
of food.
Obesity is a growing problem:
- More than 1 billion people worldwide are overweight
(WHO, 2007)
- The U.S. adult obesity rate has more than doubled in the
last 40 years
- Significant obesity increases the risk of diabetes, high blood
pressure, heart disease, gallstones, arthritis, and certain types
of cancer (Olshansky et al., 2005).
-In 2004 the U.S. Medicare system began recognizing obesity
as an illness
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Obesity Measured as Body Mass
Index (BMI)
The World Health
Organization and many
countries define obesity as
a BMI of 30 or more
(although muscular bodies
may also have a
high BMI).
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Social Effects of Obesity
When women applicants were made to look
overweight, subjects were less willing to hire
them.
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Physiology of Obesity
The immediate determinants of body fat are the size and
number of fat cells. Once the number of fat cells
increases—due to genetic predisposition, early childhood
eating patterns, or adult overeating—it never decreases.
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Set Point and Metabolism
Once we become fat, we require less food to maintain
our weight than we did to attain it. When reduced from
3,500 calories to 450 calories, weight loss was a minimal
6% and the metabolic rate a mere 15%.
The obese defend their weight by conserving energy. 31
Genetic Influences
Studies reveal a genetic influence on body weight:
-Adoptive siblings’ body weights are uncorrelated with one
another or their adoptive parents. Rather, resembling those of
their biological parents (Grilo & Pogue - Geile, 1991).
-Identical twins have similar weights, even when reared apart
-With an obese parent a boy is 3 times and a girl 6 times more
likely to be obese
-Scientists have discovered genes that influence body weight
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Environmental Influences on
Obesity
Environmental factors that affect obesity:
-Social influence
-Sleep loss
-Changing activity levels worldwide
-Changing food consumption patterns
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Losing Weight
In the US, two-thirds of the women and half of
the men say they want to lose weight. The
majority of them lose money on diet programs.
Remember that permanent weight loss is
difficult. Set realistic and moderate goals and
lose weight gradually.
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Waist Management
Tips to lose weight
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Begin only if you are motivated
Minimize exposure to tempting food cues
Take steps to boost metabolism
Eat healthy foods
Don’t starve all day and eat at night
Beware of the binge
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Waist Management
As life-styles have become more sedentary and TV watching has
increased, so has the percentage of overweight people in Britain,
North America, and elsewhere.
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