theories of motivation hunger motivation eating disorders general psych 1 modules 33 & 34 april...
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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
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
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
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