What is motivation?
A need or desire that energizes behavior and directs
it towards a goal.
What motivates us?
Five theories attempt to explain
motivation:
1.
2.
3.
4.
5.
Instinct Theory
Drive-Reduction Theory
Incentive Theory
Arousal Theory
Hierarchy of Needs
Instinct Theory
Instincts are complex behaviors
patterns that are not learned.
Instinct Theory says we are
motivated by our inborn
automated behaviors.
But instincts only explain why
we do a small fraction of our
behaviors.
Drive-Reduction Theory
Our behavior is motivated by BIOLOGICAL
NEEDS.
The aim of drive reduction is homeostasis,
the maintenance of a steady internal state
When we are not in a homeostatic state, we
have a need that creates a drive.
Examples
Shiver when your are cold to increase body
temperature
Eat to reduce hunger-drive
Drink to reduce thirst-drive
Incentive
Where our needs push, incentives (positive
or negative stimuli) pull us in reducing our
drives.
Example
A food-deprived person who smells baking bread
(incentive) feels a strong hunger drive.
Arousal Theory
We are motivated to seek an
optimum level of arousal.
Examples
Going to a horror movie
Riding a roller-coaster
Yerkes-Dodson Law says we
perform better under increased
levels of arousal (stress), but
only up to a certain point…
Maslow’s Hierarchy of Needs
Abraham Maslow said
we are motivated by
needs, and all needs
are not created equal.
We are driven to satisfy
the lower level needs
first.
Biological Basis of Hunger
Hunger does not come from our stomach.
It comes from our brain
Researchers removed rat stomachs, connected the
esophagus to the small intestines, and the rats still
felt hungry (ate food).
What part of the brain?
The Hypothalamus
Hypothalamus
Lateral Hypothalamus
When stimulated it makes you
hungry.
When lesioned (destroyed)
you will never be hungry
again.
Ventromedial Hypothalamus
When stimulated you feel full.
When lesioned you will never
feel full again.
Hypothalamus & Hormones
The hypothalamus monitors a number of hormones that
are related to hunger.
Hormone
Tissue
Response
Orexin increase
Hypothalamus
Increases hunger
Ghrelin increase
Stomach
Increases hunger
Insulin increase
Pancreas
Increases hunger
Leptin increase
Fat/Adipose cells Decreases hunger
Set Point Theory
• The hypothalamus acts like a thermostat.
• Wants to maintain a stable weight.
• Activates the lateral when you diet and activates the
ventromedial when you start to gain weight.
• Monitors fat
Obesity
Severely overweight to the point where it causes
health issues.
Due to both nature and nurture.
Body Mass Index (BMI)
Weight divided by height,
squared
BMI of 25-29.9 is
overweight
BMI of over 30 is obese
Problems using BMI?
Body fat = fat weight divide
by total weight
Women – Above 32% is
obese
Men – Above 25% is
obese
Eating Disorders
Anorexia Nervosa
A disorder in which a
normal-weight person
(usually an adolescent
woman) continuously loses
weight but still feels
overweight.
Starve themselves to below
85% of their normal body
weight.
Eating Disorders
Bulimia Nervosa:
A disorder characterized by
episodes of overeating,
usually high-calorie foods,
(binging) followed by
vomiting, using laxatives,
fasting, or excessive
exercise (purging).
Eating Disorders
Binge Eating Disorder
(BED):
A disorder characterized by
recurrent episodes of
overeating, usually highcalorie foods, (binging).