How does motivation direct and energize behavior? Variety of approaches in psychology.
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Transcript of How does motivation direct and energize behavior? Variety of approaches in psychology.
How does motivation direct and energize behavior?
Variety of approaches in psychology
Instinct approaches
Instincts EnergyChannels behavior in appropriate direction
Instinct approach
Behavior “hard-wired” into the nervous system
Provide survival value
More common in lower animals
Doesn’t meet the complexity of most human behavior
Modified by experience
Drive reduction approach
Satisfying our needs
Primary drives for Biological needs
Examples: hunger and thrist
Secondary drives based on prior experience
Examples: achievement and belongingness
Drive reduction
Strengths:
Primary drives satisfied
Homeostasis for bio needs
Weaknesses:
Humans and other animals seek new experiences
Drive reduction doesn’t explain
Curiosity
Sensation seeking
Animals want to increase level of arousal
Exploration
Risk taking
Incentive approaches
Motivation’s “pull”
Behavior not always motivated internally
External motivation
Incentives
Contrasting approaches
Drive reduction
“push”
5 hours since last meal
hunger
Incentive theory
“pull”
Ice cream truck
Palatability (good tasting)
What are biological and social factors that underlie hunger?
Biological and Social
Biological: based on primary drive
Social: preferences heavily influenced by experience and culture
Ex: Grasshoppers and Worms in tacos
Ok in Mexico
Not Ok at Taco Bell in New Britain
Primary drive
Internal mechanisms regulate the quantity of food intake
And kinds of food desired
Animals given the choice of wide variety of foods
Choose a fairly well-balanced diet
Very rarely gain weight (except pets)
Biological factors
Chemical composition of blood (glucose)
Factor in controlling eating
Monitored by hypothalamus
On and off switches
Hypothalamus as monitor
Acts like thermostat in heating system
Heat comes on
Reaches temperature
Heat shuts off
Negative feedback loop
Hunger switches
Damage lateral hypothalamus (LH)
Animal refuses to eat
LH may act as “on” switch
Hunger sensor
Damage ventromedial hypothalamus (VMH)Animal eats too muchVMH may act as “off” switchSatiation sensor
VMH rat
400% wt increase
Finicky
Prefer good tasting food (palatable)
Not willing to work for food
Make great house guests
Human weight regulation
Weight set point a key factor
Particular level of weight the body strives to maintain
Changing set point
Raise set point Food consumption increases
Lower set point Food consumption decreases
Set point and genetics
High metabolic rate
Eat without gaining wt
Low metabolic rate
Gain wt easily
Other factors which affect eating
Meals by the clock
Meal size unrelated to energy expended
Highly palatable foods may be high in calories
Eat for emotional or social reasons
Theory 1: External cues and obesity
Obesity
Oversensitivity to external cues
Based on social convention
(Sight, availability, time of day)
Insensitivity to internal cues
(stomach contractions)
Ignoring internal cues
Stanley Schacter Early work by Stunkard Subjects swallow gastric balloonBalloon registers stomach contractionsNormal wt subjects reported hunger when stomach contractedObese subject paid little attention to internal cues
Govern eating by external cues
Palatability
Subjects given either “decent” vanilla shake or one spiked with bitter quinine
decent bitter
Normal 10 oz 6 oz
Obese 14 oz 3 oz
Average amount of shake consumed
Availability
Have to work to get food
Bag of almonds on desk while waiting
How many subjects ate almonds
with shells without shells
Normal 10/20 11/20
Obese 1/20 19/20
Other external cues
Eat by the clock
Sight of other people eating
Social settings
Why oversentive?
Schacter: oversensitivity to external cues causes overeating
Richard Nisbett (grad student with Schacter):
Just the reverse
Overeating causes increase in sensitivity
Overeating alters body’s set point for weight
Theory 2: Set point
Obese Person Higher set point
Eat more to feel satisfied
If eat less, become very sensitive to external cues
Set Point theory
Set Point -------
# of fat cells Size of cells Body weight
Gaining weight
Increase in body weight
Increase in # and size of fat cells
Raises set point
# of fat cells Size of cells Body weight
Losing weight
Any loss of weight after age of two
No decrease in # of fat cells
Decrease in size
Weight set point doesn’t drop
Lowest possible weight gets “stuck”
# of fat cells Size of cells Body weight
Restrained eaters
Fighting to loose weight
Body sending out starvation signals
Can hold themselves back (restrain)
Stay on strict diet
Give in to desire to eat
Likely to binge
Yo-Yo effect
95 % of wt lost is regained within a year
Some dieters put on more wt than lost
Famine hypothesis
Fat cells “think” there must be a famine while dieting
Rebound when person stops diet to help body survive the next “famine”
Theory 3: Settling point
Rapid rise in obesity in USA
10% population in 1980, 31% in 1991
Settling point: combo of genetics and the environment we live in
Cultural differences in diet
Americans versus Asians
Fast food nation
Advice from weight loss experts
There is no easy route to wt loss
Permanent changes in your lifestyle
Set reasonable goals
Exercise: critical factor in long run
Avoid fad diets
Don’t feel guilty