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Introduction to Motivation: Hunger

Module 26

This is a very wordy unit, I strongly recommend paraphrasing.

Link: Battle at Kruger 8:24

QR code for SG 26 27 28

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Motivation Overview

Motivational Concepts Instincts and Evolutionary

Psychology

Drives and Incentives

Optimum Arousal

A Hierarchy of Motives

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Think about why you did the following things based on your experience during

the past 4 weeks.1. Drank water2. Ate healthy food3. Ate unhealthy food4. Selected a piece of new clothing or shoes5. Got in a fight with a family member or friend6. Drove faster than the speed limit or other

dangerous driving7. Study for a test8. Take a test without studying9. Did something exciting or risky like ride a

rollercoaster, walk through a rough part of the hood, etc.

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Motivationa need or desire that energizes behavior and directs it towards a goal.

-Specific need or desire, such as hunger, thirst, or achievement, that prompts goal-directed behavior

Aron Ralston

AP

Photo/ R

ocky Mountain N

ews, Judy W

algren

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Perspectives on Motivation

Four perspectives are used to explain motivation:

1. Instinct/Evolutionary Theory

2. Drive-Reduction Theory

3. Arousal Theory4. Hierarchy of Motives

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Instincts & Evolutionary Psychology

Instincts are complex behaviors that have fixed patterns throughout different species

and are not learned (Tinbergen, 1951).

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

© A

riel Skelley/ M

asterfile

Tony B

randenburg/ Bruce C

oleman, Inc.

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Drive Reduction Theory

Instinct theory of motivation 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 (Hull, 1951).

Tension

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Drive Reduction Theory Cont.

• Primary Drives– Unlearned

• Food• Water• Temperature regulation

FoodDrive

Reduction

Organism

Stomach FullEmpty Stomach(Food Deprived)

• Secondary Drives– Learned

• Money• Shelter• Job

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Homeostasis

-tendency to maintain a balanced or constant internal state

-regulation of any aspect of body chemistry around a particular level

Biological Equilibrium

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Incentive

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.

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Yerkes-Dodson Law: 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.

Harlow

Prim

ate Laboratory, U

niversity of Wisconsin

Randy F

aris/ Corbis

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The Arousal-Performance Relationship

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Intrinsic and Extrinsic Motivation

• Intrinsic motivation– Motivation for a behavior is the behavior

itself

– Children playing is an example

• Extrinsic motivation– Behavior is performed in order to obtain

a reward or to avoid punishment

– A bonus program is an example

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A Hierarchy of MotivesAbraham 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.

(1908-1970)

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Hierarchy of Needs

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Motivation and Hunger

Hunger Overview The Physiology of Hunger

The Psychology of Hunger

Obesity and Weight Control

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Hunger

When are we hungry?

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.

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The Physiology of HungerStomach contractions (pangs) send signals

to the brain making us aware of our hunger.

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

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

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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.

Rat Hypothalamus

Glucose Molecule

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Body Chemistry & Leptin• Fat cells in our body produce leptin

• Hypothalamus monitors these levels

• High levels of leptin signal the brain to reduce appetite or increase the rate at which fat is burned.

• Leptin deficiency can cause obesity

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Hypothalamic CentersThe 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. Lateral nucleus – Causes us to start eating and keep eating. (LATERAL)

"Late night snack":

LATEral is snacking [feeding]

center.

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Hypothalamic Centers

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

VMH, and the animal eats excessively.

Richard H

owardVentromedial nucleus - Causes us

to stop eating and not be interested in food. (VomitMeal)

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Hypothalamus & Hormones

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

Hormone Tissue ResponseOrexin increase

Hypothalamus

Increases hunger

Ghrelin increase

StomachIncreases hunger

Insulin increase

PancreasIncreases hunger

Leptin increase

Fat cellsDecreases hunger

PPY increaseDigestive tract

Decreases hunger

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Blood vessels supply the hypothalamus, enabling it to respond to our current blood chemistry as well as to incoming neural information about the body’s state. The hypothalamus controls eating and other body maintenance functions

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Motivation-Hunger

Set Point the point at which an individual’s

“weight thermostat” is supposedly set when the body falls below this weight,

an increase in hunger and a lowered metabolic rate may act to restore the lost weight

Basal Metabolic Rate body’s base rate of energy expenditure

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The Hypothalamus and Hunger

Adapted from Schwartz et al., 2000.

Ana Bolic (fat girl)

Cat Abolic (thin cat)

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Basal Metabolic Rate

• The rate at which the body uses energy for vital functions while at rest

• What influences BMR…

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The Psychology of Hunger

Memory 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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Cognition/Unconscious and Hunger

• Think for a moment about why you eat food…

• You probably think you eat food because it tastes so good right?

• But, how big is the BOX?

• You decide how much to eat by how big the BOX is as much as how it tastes.

• If this is true is it a CONSCIOUS choice?

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Taste Preference: Biology or Culture?

We tend to avoid novel foods…this is probably adaptive.

Richard O

lsenius/ Black S

tar

Victor E

nglebert

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Hot Cultures like Hot Spices

Countries with

hot climates

use more

bacteria-inhibiting spices in meat dishes.

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Eating DisordersAnorexia

Nervosa: A condition in

which a person refuses to eat.

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Eating Disorder: Bulimia Nervosa

• Intense fear of being fat.

• Characterized by binging episodes.

• Often followed by purging – Vomiting– Laxatives– Excessive exercise

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Reasons for Eating Disorders

1. Sexual Abuse: Childhood sexual abuse does not cause eating disorders.

2. Family: Younger generations at greater risk 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.

4. Obsessive-compulsive disorder – need to control

5. Depression and low-self esteem

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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.

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Obesity

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://ww

w.cyb

erd

iet.co

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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.

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Body Image (Women)Western culture tends to place more emphasis on a thin body image in comparison to other cultures.

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Factors Contributing to Being Overweight

• Highly palatable food—we eat because it tastes so good

• Supersize It—food portions are larger than necessary for health

• Cafeteria Diet Effect—more food and more variety leads us to eat more

• Snacking—does not cause us to eat less at dinner

• BMR—changes through the lifespan

• Sedentary lifestyles- we don’t move around much

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Body Mass Index (BMI)

Obesity in children

increases their health risks…

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Obesity and MortalityThe death rate is high among very

overweight men.

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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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Social Contagion

• Obesity is contagious…• If your friends are obese you are more likely to

be obese.• What about change…

– If your friend gains a couple pounds you are more likely to gain a couple pounds.

• Your risk of infection…– If a friend becomes obese you are 57% more likely to

become obese– Friend of a friend…20% more likely to gain weight

too. (with friends of the same sex)

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Physiology of Obesity

Fat Cells: may divide, they may shrink but never disappear.

Makes it easier to add fat in the future.

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Set-Point Theory

• According to the set-point theory, there is a control system built into every person dictating how much fat he or she should carry – a kind of thermostat for body fat.

• We don’t know how to change the set-point yet…activity looks like the best bet.

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Set Point and MetabolismWhen 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.http://www.cbsnews.com/stories/2004/07/12/60II/main628877.shtml

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The Genetic FactorIdentical 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

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ActivityLack of exercise is a major contributor to

obesity. Watching TV for two hours resulted in a 23% increase of weight when other

factors were controlled (Hu & others, 2003).

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Food ConsumptionOver the past 40 years, average weight gain has

increased. Health professionals are pleading with US citizens to limit their food intake.

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EXPLORING PSYCHOLOGY(7th Edition in Modules)

David MyersPowerPoint Slides

Aneeq AhmadHenderson State

University, Bernstein, Lahey, and Amy Jones with

Garber edits

Worth Publishers, © 2008