Theories of MotivationHunger MotivationEating Disorders

General Psych 1Modules 33 & 34

April 19, 2005Class #23

Motivation

The underlying processes that initiate, direct and sustain behavior in order to satisfy physiological and psychological needs or wants

Theories of Motivation Instinct Theory Drive Reduction Theory Arousal Theory

Optimal Level Hypothesis Yerkes-Dodson Law

Incentive Theory

Instinct Theory

Instinct Complex unlearned response triggered by a

stimulus or complex stimulus

Do humans have instincts? Early Darwinian Theory (1800’s) proposed

the idea of instinct, arising from genetic endowment

William James (1890) proposed an instinct theory in humans

Instincts were goal directed predispositions to behavior

Instinct Theory

Paradox in Psychology: As others were showing that animal

behavior could be modified by learning (Thorndike), James was proposing that much of human behavior was unlearned

William McDougall (1908) followed… Suggested their were 18 instincts

Instinct Theory

McDougall (1908) theorized that motivated behaviors are instinctual: Unlearned Uniform in expression (do not change

with practice) Universal (all members of a species

show the same behavior)

Too many limitations… By 1924 instinct theory was becoming

obsolete as there were several criticisms: Too many instincts

Researchers came up with 5759 of them Logic was circular

i.e. the only evidence that an instinct exists was the behavior it supposedly explained

He’s an “overachiever” because he’s “hard-working” She’s “hard-working” because she’s an “overachiever”

Just meaningless labels with no explanations

Drive Reduction Theory (Hull, 1943)

Supporters of this theory believe that when a need requires satisfaction, it produces drives These are tensions that energize behavior

in order to satisfy a need Thirst and hunger are, for instance,

drives for satisfying the needs of eating and drinking, respectively

Drive Reduction Theory

Drives have been generally established as primary and secondary… Primary drives satisfy biological needs and must be

fulfilled in order to survive Homeostasis is the motivational phenomenon for

primary drives that preserves our internal equilibrium. This is true, for example, for hunger or thirst

Secondary drives satisfy needs that are not crucial to a person's life 

Criticism

Critics felt that this theory was inadequate in explaining secondary drives

Arousal Theories

Optimal Level Hypothesis Yerkes-Dodson Law

Optimum Arousal Theory:

Hebb (1955) and Zuckerman (1984)

This theory argues that we all have optimal levels of stimulation that we try to maintain…

Optimal Level Hypothesis we seek an optimal level of arousal too little stimulation, we seek an

increase too much, we seek to decrease

Eysenck (1967)

Extraversion-Introversion Introverts were over-

aroused individuals therefore they try to keep stimulation to a minimum

Extroverts were under-aroused individuals, therefore they tried to increase stimulation

Eysenck (1967)

Cortical Arousal Differences Eysenck suggests that the difference

between introverts and extroverts depends on the ascending reticular activating system (ARAS)

Causes introverts to be “stimulus shy” Causes extroverts to be “stimulus

hungry”

Cortical Arousal Differences

Geen (1984) Introverts and extraverts choose different

levels of stimulation, but equivalent in arousal under chosen stimulation

Extroverts chose to hear louder noises than introverts

After put in their chosen environment their HR’s are the same

This seems to suggest that being at their preferred level of stimulation results in the same overall level of arousal for both groups

Geen (1984)

Researcher tested four other groups: Introverts placed in environment that other

introverts had chosen (II) Introverts placed in environment that

extroverts had chosen (IE) Extroverts placed in environment that other

extroverts had chosen (EE) Extroverts placed in environment that

introverts had chosen (EI)

Geen (1984) II = similar HR as free choice introverts IE = higher HR than free choice

introverts when forced to listen to extroverts’ noise

EE = similar HR as free choice extroverts

EI = lower HR than free choice extraverts when forced to listen to introverts’ noise

Geen (1984)

Performance on a learning task was also affected: Introverts did best in introvert-selected

environment Extraverts did better in extravert-selected

environment Practical implications:

Roommates? Mate Selection?

Sensation Seeking Marvin Zuckerman (1971)

Currently, a professor at the University of Delaware

Defined “sensation seeking” as "a trait describing the tendency to seek novel, varied, complex, and intense sensations and experiences and the willingness to take risks for the sake of the experience"

These people want to avoid boredom at all costs

Zuckerman (1994) Skydivers are characterized with both higher

sensation seeking ambitions and a search for thrilling experiences, than most other partakers of other risky activities

It is claimed that high sensation seekers believe risks to be not as great as do low sensation seekers

The sensations are also valued less by the low sensation seeker

An earlier view of psychologists in the late fifties was that skydivers had an inherent death wish

Is there a connection between sensation seekers and psychopaths?

Impulsive Unsocialized Sensation Seeking Zuckerman feels that those very high on sensation

seeking may lack the capacity to inhibit behavior that might be detrimental to society

Trouble inhibiting impulsive action Thrills at all costs regardless of the consequences to

others High sensation seekers are less tolerant of sensory

deprivation and they require much stimulation to get to optimal level of arousal

Hebb's theory of optimal level of arousal applies

Yerkes-Dodson Law (1908)

This old psychological principle is the belief that there is an optimal amount of arousal which is necessary to help a person who is performing a task

This principle can be simply stated as follows: A certain amount of arousal is beneficial to

someone performing a well-learned task That same amount of arousal will likely produce

detrimental results when the task is not well-learned

Criticism of Optimum Arousal Theories

People differ greatly in the optimal level of arousal they seek… These theories do not explain why

Incentive Theory Viewpoint on motivation that is different than

instinct, drive , and arousal theories Suggests that behavior is pulled rather than

pushed… Emphasizes the role of environmental stimuli that

can motivate behavior by pulling people toward them rather than pushing people to satisfy a need (as in the drive-reduction theory)

Suggesting that people act to obtain positive incentives and avoid negative incentives

Explains secondary drives much better than drive-reduction theory

Criticism

Some behaviors seem to be pushed as well

Abraham Maslow (1908-1970)

Born in Brooklyn, NY His parents were uneducated

Jewish immigrants from Russia

Hoping for the best for their children – they pushed them hard towards education

He became very lonely as a youth and found his refuge in books

To satisfy his parents, he entered law school at CCNY and then Cornell

Abraham Maslow

Against his parents wishes, he married his first cousin and moved with her to Wisconsin where he became interested in psychology and gets his BA in 1930, MA in 1931, and Ph.D. in 1934 at the Univ. of Wisconsin

In 1935, he returns to NY and works with Thorndike at Columbia and eventually begins teaching full-time at Brooklyn College and then becomes chair of psych department at Brandeis where he begins his crusade for humanistic psychology

Maslow’s Hierarchy of Needs (1970)

Abraham Maslow proposed that there are five levels of motives, or needs, arranged in a hierarchy: Physiological Safety Belongingness and love Esteem Self-actualization

We must satisfy needs or motives low on the hierarchy before we are motivated to satisfy needs at the next level

Physiological Needs Physiological needs are

basic, instinctual needs for air, food, water, and sex, among others. These needs must be at least partially met in order to ascend the hierarchy.

These needs can also be arranged in their own hierarchy.

Safety Needs Safety needs include

things such as shelter, security, and protection from physical and emotional harm.

Belonging Needs These needs are met

by having meaningful relationships, such as significant others, friends and children

Esteem Needs This level has two sub-

levels Low esteem needs are

the needs for the respect of others – need for recognition, etc.

Higher esteem needs are the needs for self respect –to achieve, to be competent, to be independent, etc.

Self Actualization Self actualization

involves becoming the most complete person that you can be – your full potential

Criticisms

Some critics felt that it is possible to skip levels

Others felt that they could not be applied universally

Theories of Hunger Motivation What triggers our motivation to eat?

Internal Factors An empty stomach? Body Chemistry Hypothalamus Set Point Theory

External Factors Externality Hypothesis

Other Factors Emotion Habit Attention

Internal Factors

An empty stomach? Early researchers thought that hunger pangs

were important - caused by contraction of stomach

Cannon and Washburn (1912) tested the hypothesis that the contraction of the stomach is the cue to start eating

Tested this by having Washburn swallow a balloon and measuring contractions of the stomach by looking at contractions of the balloon (changes in air pressure go out stomach via tube to measuring device)

An empty stomach?

Tsang (1938) Removed rats stomachs and attached their

esophagus to their small intestine They still displayed actions associated with

hunger

Body Chemistry

Blood Glucose This is a simple sugar used by most cells in the

body for energy - most food ultimately gets converted to blood glucose

Decreasing blood glucose levels sense of hunger

Insulin This is a hormone that increases the flow of

glucose into body cells, diminishing the amount of glucose in the blood by converting it into stored fat

Decreasing blood glucose levels sense of hunger

Body Chemistry

Glucagon This hormone helps convert stored energy

supplies (stored fat) back into blood glucose

Increasing blood glucose levels hunger decreases

Lesions of Hypothalamus

The destruction or stimulation of the lateral and ventromedial areas causes animals to ravenously decrease or increase their weight See picture on page 462 for example of

increase

Set Point Theory

Set point is the weight that your body wants to be… It is a self-regulatory system that maintains

your body weight If you starve yourself the hypothalamus

activates compensatory mechanisms, your metabolism slows so that energy stores are used more sparingly and the amount of insulin that is produced increases so that more of the food that you take in remains as fat (this makes it possible to maintain weight on a meager diet)

What triggers our motivation to eat?

External Incentives Rodin (1981)

Like Pavlov’s dogs people learn to salivate in anticipation of appealing foods

Externality Hypothesis (Schacter, 1978) Did research on obese humans They argue that the difference between obese

and normal weight subjects is that the obese are overly responsive to external stimuli (cues for eating)

Externality Hypothesis VMH-lesioned rats and obese humans are

similar in interesting ways: Both are more "finicky" than controls. Both are

less willing to work for food VMH-lesioned rats don't eat as much of a bad

tasting food as do control rats Obese humans don't drink as much of a bad-

tasting milk shake as do control humans VMH-lesioned rats don't bar-press for food on

"lean" schedules as readily as do the control rats Obese humans eat fewer peanuts than do control

humans if they have to shell them, but more if they don't have to do this work

 

Externality Hypothesis

These findings support Schacter's conclusion that  both VMH-lesioned rats and obese humans are more sensitive to external cues related to food than to the internal cues provided by their bodies. Obese humans are more likely to eat more when they are

misled into thinking it's lunchtime than are control humans - again evidence of the influence of external cues

Social Factor is another external cue Eating around others often increases food intake

Other Factors

Emotion Depressed people may eat too much or too

little Habit

Meal time - ancient Romans only ate two meals a day. We eat three - if we miss a meal, we feel hungry at that meal time

Attention Awareness vs. non-awareness

Eating Disorders

Obesity Anorexia Nervosa Bulimia Nervosa

Obesity

Weight which is 20-40% above the normal standard for a person’s height (BMI over 30 kg/m2) Rates of obesity are climbing and have risen from

12 to 20 percent of the population since 1991. An ominous statistic which indicates that the

epidemic of obesity may get even worse is that the percentage of children and adolescents who are obese has doubled in the last 20 years

Why is this happening?

Obesity Why do some people become

seriously overweight? Emotional problems

Depression Anxiety

Sedentary lifestyle Too much TV and not

enough exercise But Cookie Monster is

trying to send a new message

Genetics Higher set point

Anorexia Nervosa

Anorexia Nervosa Self-starvation and severe weight loss 95% women Usually begins in early teen-age years and

continues into one’s 20’s and 30’s and beyond

Usually starts as an innocent diet that went out of control

They eat less and exercise more Often they come from high-achieving or

over-protective families At first, self-esteem was raised – “you look

great”

Anorexia Nervosa Symptoms

Refusal to maintain body weight Distortion of body image Amenorrhea Slow heart rate Low blood pressure Low body temperature Depression, obsessions, compulsions

Anorexia Nervosa Complications

Hypothermia may result Results when the body’s natural

isolation fat stores become non-existent and the victim becomes cold all the time

Some must be tube-fed to prevent death Some will die from heart failure

Anorexia Nervosa

Prognosis With individual, group, and family therapy

there is a good chance for improvement and hopefully recovery

Anti-depressants are often combined with these therapies

It is a life-long process though

Bulimia Nervosa Disorder characterized by repeated binge-

purge episodes of overeating followed by vomiting or using a laxative

Again, mostly women in their early teens These individuals can be thin, average in

weight or even overweight – so this one is more likely to go unnoticed by family or friends

Bulimia Nervosa

Symptoms of Bulimia Eating binges Purging Sore throat Mouth and throat ulcers Swollen salivary glands Destruction of tooth enamel Depression, obsessive-compulsive symptoms

Bulimia Nervosa

Prognosis With the long-term psychotherapy

combined with group and family therapy the patient will likely improve

Often, anti-depressants are combined with therapy

Again, this is a life-long process