MOTIVATION

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PERSPECTIVES ON MOTIVATION

Five perspectives used to explain motivation include the following:

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1. Instinct Theory (replaced by the evolutionary perspective)

2. Drive-Reduction Theory3. Arousal Theory4. Hierarchy of Motives5. Incentive Theory

INSTINCTS & EVOLUTIONARY PSYCHOLOGYInstincts are complex behaviors that

have fixed patterns throughout different species and are not learned

(Tinbergen, 1951).

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Where the woman builds different kinds of housesthe bird builds only one kind of nest.

© A

riel Skelley/ M

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Tony Brandenburg/ B

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an, Inc.

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.

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INCENTIVE

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Where our needs push, incentives (positive or negative stimuli) pull us in reducing our

drives.

A food-deprived person who smells baking bread (incentive) feels a strong hunger drive.

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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Harlow

Prim

ate Laboratory, U

niversity of Wisconsin

Randy F

aris/ Corbis

A HIERARCHY OF MOTIVES

Abraham Maslow (1970) suggested that certain needs have priority over

others. Physiological needs

like breathing, thirst, and hunger

come before psychological needs

such as achievement, self-esteem, and the

need for recognition.

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(1908-1970)

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HIERARCHY OF NEEDS

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ario Tama/ G

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David P

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Joe Skipper/ R

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HUNGER

When are we hungry?

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When do we eat?

When there is no food in our stomach.

When we are hungry.

How do we know when our stomach is empty?Our stomach growls. These are also

called hunger pangs.

THE PHYSIOLOGY OF HUNGER

Stomach contractions (pangs) send signals to the brain making us aware

of our hunger.

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STOMACHS REMOVED

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Tsang (1938) removed rat stomachs, connected the esophagus to the small

intestines, and the rats still felt hungry (and ate food).

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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Rat Hypothalamus

HYPOTHALAMIC CENTERS

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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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HYPOTHALAMIC CENTERS

The ventromedial hypothalamus (VMH) depresses hunger (stimulation). Destroy the

VMH, and the animal eats excessively.

Richard H

oward

Hormone Tissue Response

Orexin increase

Hypothalamus

Increases hunger

Ghrelin increase Stomach

Increases hunger

Insulin increase Pancreas

Increases hunger

Leptin increase Fat cells

Decreases hunger

PPY increaseDigestive tract

Decreases hunger 15

HYPOTHALAMUS & HORMONES

The hypothalamus monitors a number of hormones thatare related to hunger.

SET POINT

Manipulating the lateral and the ventromedial hypothalamus alters the body’s “weight thermostat.” Heredity

influences set point and body type.

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If weight is lost, food intake increases and energy expenditure decreases. If weight is gained, the opposite takes place.

Figure 10.5 The heritability of weight

THE PSYCHOLOGY OF HUNGERMemory plays an important role in hunger. Due to difficulties with retention, amnesia patients eat frequently if given food (Rozin

et al., 1998).

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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!

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Richard O

lsenius/ Black S

tar

Victor E

nglebert

HOT CULTURES LIKE HOT SPICES

Countries with hot climates use more bacteria-inhibiting spices in meat

dishes.

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EATING DISORDERS

Anorexia Nervosa: A condition in which a normal-weight person (usually

an adolescent woman) continuously loses weight but still feels overweight.

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Reprinted by perm

ission of The N

ew E

ngland Journal of M

edicine, 207, (Oct 5, 1932), 613-617.

Lisa O

’Connor/ Z

uma/ C

orbis

EATING DISORDERS

Bulimia Nervosa: A disorder

characterized by episodes of overeating,

usually high-calorie foods, followed by

vomiting, using laxatives, fasting, or excessive exercise.

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REASONS FOR EATING DISORDERS1. Sexual Abuse: Childhood sexual

abuse does not cause eating disorders.

2. Family: Younger generations develop eating disorders when raised in families in which weight is an excessive concern.

3. Genetics: Twin studies show that eating disorders are more likely to occur in identical twins rather than fraternal twins. 23

OBESITY AND WEIGHT CONTROL

Fat is an ideal form of stored energy and is

readily available. In times of famine, an

overweight body was a sign of

affluence.24

OBESITY

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A disorder characterized by being excessively overweight. Obesity increases

the risk for health issues like cardiovascular diseases, diabetes, hypertension, arthritis, and back

problems.

WHAT IS OPTIMAL WEIGHT?

BMI = Body Mass Index. YOUR WEIGHT x 705/ ht x ht. Obese if >30, Over weight > 25.

WHR – Waist/Hip Ratio Distribution of fat.

THE GENETIC FACTOR

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Identical twin studies reveal that body weight has a genetic basis.

The obese mouse on the left has a defective gene for the hormone leptin. The mouse on the right sheds 40% of its

weight when injected with leptin.

Courtesy of John S

oltis, The R

ockefeller University, N

ew Y

ork, NY

FOOD CONSUMPTION

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Over the past 40 years, average weight gain has increased. Health professionals

are pleading with US citizens to limit their food intake.

LOSING WEIGHT

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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.

INTERESTING CULTURAL NUTRITIONAL PARADOXES

The Japanese eat very little fat and suffer fewer heart attacks than the British or Americans.

The French eat a lot of fat and also suffer fewer heart attacks than the British or Americans.

The Japanese drink very little red wine and suffer fewer heart attacks than the British or Americans.

The Italians drink excessive amounts of red wine and also suffer fewer heart attacks than the British or Americans.

The Germans drink a lot of beers and eat lots of sausages and fats and suffer fewer heart attacks than the British or Americans.

CONCLUSION (?): Eat and drink what you like. Speaking English is apparently what kills you.

LOOK GOOD, FEEL GOOD.

Improves mood, well-being.

Reduces anxiety, depression, and stress.

Increase self-esteem, self-acceptance.

Work performance and attitude improves

WHY DO WE GAIN WEIGHT?

1. Biological factors- Metabolic rates vary - OB gene, leptin, CCK

2. Set point theory: Only constant exercise will

change it.

3. Fat cells: can increase but never

decrease, grow large and small.

4. Gender: Fat distribution:

Men: chest, abs, nape of neck, lower back.

Women: hips, thighs, behind.

Android fat (apple) can be lost more easily than gynoid (pear).

5. Temptation- Do not LOOK at dessert if tendency to be heavy.

SUMMARY

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