1200 words and three scholarly sources
1.
In this weeks narrative essay, how would you apply your learnings from unit 3 to families and relationships? How would you distinguish between a health and an unhealthy family relationship? Your response will need to address each question or statement listed above in an essay format using at least three scholarly sources and at least a minimum of 1200 words.
Axons from the sympathetic nervous system form connections
in the gut, contributing to those butterflies we feel at times of
excitement.
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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The
Feeling
Mind
Motivation and Emotion
1 Differentiate emotion and motivation, and analyze their relationship to each other.
2 Analyze the physiological and environmental factors that influence hunger and eating.
3 Assess the roles of evolved preferences and physiological and environmental factors in sexual
motivation, considering how this motivation varies with gender and over time.
4 Compare and contrast achievement and affiliation motivation in terms of predictors and
implication for life outcomes.
5 Associate aspects of emotional responding with activation of central and autonomic nervous
system structures.
6 Evaluate the roles of nature, nurture, and their interaction in explaining human
communication of emotion, based on research evidence.
7 Differentiate major theories of emotion in terms of the relationship between physical
sensations and subjective feelings.
Learning Objectives
287
Motivation and emotion, the topics of this chapter,
involve neural circuits that often operate below the level of our conscious
awareness. We dont decide consciously to feel happy or sad or
hungry or thirsty, but instead, we react somewhat automatically
to the environment around and within us. We can zoom
in to look at these neural circuits, like these sympathetic
axons (in blue) forming connections with the gut. We
have all had the feeling of butterflies in our stomach
when we are excited, and neural pathways like this one
are responsible for such feelings.
Zooming out, we can examine motivation and
emotion in the larger context of the individual using
the example of elite athletes at the Olympic Games. The
2008 Beijing Olympics featured 11,028 athletes who rep-
resented the very best in their respective sports, just a tiny
fraction of the millions of people who compete in athletics
worldwide. To stand out among these elites takes even more
Michael Steele/Allsport/Getty Images
A
rg
os
y
Pu
bl
is
hi
ng
, I
nc
.
2 Analyze the physiological and environmental factors that influence hunger and ea
3 Assessss tthehe rrooles of f evevoolvedd prprefe ereences anandd phphysysiologiicall and enenviviroronmnmentaal fafactcto
motitivavation, conssiddererining hooww ththisis mmootivvatation varies wwiithh gegendeer aand over timeme.
4 44 Compmpaare and conttrast achieevememennt andd aaffilffi iatiion mmototivivatatioon inin tterms off prreddicto
impliccatatioionn fofor lifefe ooututcomemes.
5 Associate aspects of emotional responding wiwith activation of central and autonom
systemm structures.
6 Evaluuatte thee rrololees oof nanatuture, nuurturre,, annd ttheeirr innteeracctionn iin eexplplaiaining human
commmuunicattioon of eemmotiionon, babased onon reseearrchh eeviddenncee.
7 Differentiate major theories of emotion in terms of the reelaatiionnship between phys
sensations and subjective feelingss
hi
ng
, I
nc
.
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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Chapter 7 288
extreme motivation, not to mention talent and hard work. Many athletes
competing at this level have focused on their sport to the exclusion of
most other activities since they were in elementary school. Yet of the over
11,000 participants, only 1,881 (or 17%) went home with a medal.
Given the odds of obtaining a medal, you would think that
any athlete winning one would be absolutely ecstatic, but that
is not always the case. As you can see in the photograph on the
preceding page of Olympic swimmers on the medal stand, the
athletes are showing a range of emotions. Look for a moment at
the way the three athletes are holding their flower bouquets. The
gold and bronze medalists are holding their bouquets straight
up, but the silver medalist is close to dropping his bouquet. His
entire demeanor says dejection and disappointment.
Why would a silver medalist be disappointed with such an
exceptional achievement? To answer this question, we must
zoom out even farther from the individual to consider the social
context. Psychologists have found that the reactions of these
swimmers are quite typical (McGraw, Mellers, & Tetlock, 2005;
Medvec, Madey, & Gilovich, 1995). Apparently, silver medalists
are more likely to compare themselves to gold medalists, which
leads to disappointment, while bronze medalists are comparing
themselves to the fourth-place finishers who do not get a medal
at all, which leads to joy.
In this chapter, we will explore the mechanisms responsible
for our motivations and emotions, beginning with the underly-
ing physical mechanisms and zooming out to look at individual
and, ultimately, social influences on these behaviors.
How Are Motivation
and Emotion Related?
Motivation and emotion are tightly related processes that share the experi-
ence of subjective feelings and engage similar processes and structures in
the brain. Efforts to differentiate between motivation and emotion can be
somewhat frustrating, given their overlapping characteristics and similar
definitions.
An emotion is defined as a combination of physical sensations, such
as a rapid heartbeat, and conscious, subjective feelings, like feeling afraid.
Emotions are spontaneous, automatic responses to situations. We do not
wake up in the morning and decide to feel happy or sad in the same way we
decide which clothes to wear. Instead, our emotional reactions occur auto-
matically in response to our perceptions of surroundings and situations.
We often communicate our emotions to others through behaviors such as
facial expression, body language, gestures, and tone of voice.
emotion A combination of arousal,
physical sensations, and subjective
feelings that occurs spontaneously in
response to environmental stimuli.
Emotions are automatic,
spontaneous reactions to the
world around us. We do not wake
up in the morning and consciously
decide to be happy or sad.
A
la
n
W
ill
ia
m
s/
A
xi
om
/A
ur
or
a
Ph
ot
os
leads to disappointment, while bronze medalists are compar
ththememseelvlveses to ththe e fouurtht -pplalacece fifinin sherrss who dodo nnotot gett aa mmee
at all, whwhicich h leadads s tot jjooy.
In thihis chapptter, wwee wiwilll eexplolorre tthehe mmecechahannisms s rresppoonsi
foforr our r momotit vaatitions anandd emmototioionsns, bebeginnnining wiwithth tthhe uundnderer
ing physical mechanisms and zooming out to look at individ
and, ultimately,y social influennceces on these behavviors.
autommmatic,
reactions tto the
d us. We do not wake
rning and consciously
A
la
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la
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W
i
W
ill
illi
am
s
am
/A
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/A
io
m
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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WHAT DOES IT MEAN TO BE MOTIVATED? 289
If we are thirsty following a tough workout, we are motivated to
seek a drink of water. It is unlikely that a thirsty person would be
motivated to find a hamburger instead.
Emotions can be distinguished from moods. A mood is a more general
state than an emotion. You can be in a good mood while feeling a variety
of specific emotions, such as happiness, pride, or relief. A mood generally
lasts a longer time than a single emotion. For example, when we discuss
disorders of mood in our chapter on psychological disorders, we note that
criteria for depression specify that depressed mood should characterize at
least half a day every day for a period of two weeks (American Psychiatric
Association [APA], 2000). Because emotions are responses to the ongoing
and ever-changing flow of environmental information, it is unlikely that a
single emotion would last this long.
Motivation is defined as a process that arouses,
maintains, and guides behavior toward a goal.
For example, we are motivated to seek a drink
of water in response to thirst. The process
of motivation is accompanied by distinct
emotional states. Thirst is generally quite
unpleasant, and taking a drink of water can
produce positive emotions like relief and
happiness.
Motivation and emotion share the abil-
ity to arouse an organism and stimulate
behavior, but motivation does so in a more
direct and precise fashion than emotions do.
People who feel motivated by thirst are likely
to do one thingseek out something to drink.
In contrast, experiencing the emotion of sad-
ness stimulates behavior, but that behavior may
take many different forms. Some people respond
to sadness by crying in a room by themselves,
while others will seek out the company of friends.
What Does It Mean
to Be Motivated?
Animals, including human beings, do not have unlimited time and
resources, and a state of arousal is expensive in terms of the energy it
requires. Motivational systems allow an animal to be aroused only when
necessary, such as when it needs food, and then reduce arousal following
the solution of a problem, such as after a meal. Preventing the waste of pre-
cious energy resources provides a significant survival advantage. Motiva-
tion also provides the benefit of helping an animal prepare to meet future
needs. Most animals are motivated to explore their environments, because
familiarity with an environment allows them to act more effectively when
a need arises.
S
te
ve
C
ol
e/
Ph
ot
od
is
c/
G
et
ty
Im
ag
es
motivation A process that arouses,
maintains, and guides behavior toward a
goal.
If we aree thirstty ffolllowwing aa tougughh woorkrkout, we are motiva
seeek a drrink off wwater. It is uunlikelely y ththat a thirsty person wo
motivated to fifindd a hamburger innstteada .
o arouse aan orrganism and stimulate
vior, but mootivaatit on does so iinn aa mmorre
t annd preecisese fashhion than ememotions ddo..
le who ffeel motivaatted d by thhirsrst are likkelyly
o oone tht ingseekek outt ssomethihingng ttoo drinink.k.
onontrtrast, experienccining the emotion of sad-
stimumullattes bebehahavivioro , but thatat behavior may y
manyy diffffererentn foorms. Somee peoplplee rerespponond d
adness bby crying in a roomm by ththemseelvlvess,
e others will seek out the commpapanny ooff frfriendndss.
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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Chapter 7 | THE FEELING MIND: MOTIVATION AND EMOTION290
We can think of motivation as a process that
maintains homeostasis, a term introduced by
psychologist Walter Cannon to describe a steady
internal balance or equilibrium (Cannon, 1932).
To achieve homeostasis, organisms actively
defend certain values known as set points. Under
normal circumstances, we carefully regulate such
variables as core body temperature, fluid levels,
and body weight around set points. Deviations
from these set points stimulate behavior by the
organism that is designed to reestablish the origi-
nal values. You might think about this process as
analogous to your homes temperature control.
A set point of air temperature is established
using your thermostat. If your homes tempera-
ture drops below that set point, the furnace is
activated until the set point is once again established. If your homes tem-
perature rises above the set point, the air conditioning system is activated
until the set point is regained. Similarly, if your core body temperature
drops below 98.68 F (378 C), your body initiates a number of processes
designed to increase its temperature, such as producing heat by the muscle
contractions we know as shivering. If your core body temperature rises
above its set point, cooling mechanisms are activated. You sweat, and the
evaporating moisture cools your skin. Blood is diverted to the outer parts
of the body, leading to a flushed appearance.
Motivation begins with a stimulus, from either the internal or external
environment of the organism, that serves as a cue for motivated behavior.
Stimuli that are important to survival, such as the presence of a predator
or a deficit in body fluids, generate arousal and tension, a state frequently
referred to as drive (Hull, 1943). Being in a drive state propels the organism
into some sort of action related to the stimulus, whether that means run-
ning away from the predator to safety or perhaps pulling a bottle of water
from a backpack to quench thirst. If actions are successful in regaining
equilibrium, we experience drive reduction, accompanied by a rewarding
feeling of relief.
Drive theories of motivation are often described as push theories, as
drive is seen as pushing an organism toward a goal. However, not all psy-
chologists agree that motivation requires the push of drive. Instead, they
suggest that rewards, or incentives, have the capacity to pull an organism
in a particular direction. According to this view, animals are viewed as natu-
rally inclined to act on their environment, rather than waiting passively for
a need to arise (Deci & Ryan, 2000). In incentive theories, no reference to
unpleasant internal drive states is required to explain motivated behavior.
Incentives or rewards may be intrinsic or extrinsic. Intrinsic rewards
arise internally, such as feelings of accomplishment when a goal is met.
Extrinsic rewards come from outside sources, such as money for complet-
ing work or praise from a supervisor. These different types of reward can
interact in complex ways (see Figure 7.1). In some cases, certain extrinsic
homeostasis A steady internal balance,
or equilibrium.
set point A value that is defended to
maintain homeostasis.
drive A state of tension and arousal
triggered by cues important for survival.
drive reduction The state of relief and
reward produced by removing the tension
and arousal of the drive state.
incentive A reward that pulls an
organisms behavior in a particular
direction.
intrinsic reward A reward that arises
internally.
extrinsic reward A reward from an
outside source.
Many animals are motivated to
explore their surroundings even
when they have no immediate needs,
because being familiar with your
neighborhood saves time when a
need does arise, whether that is food,
water, shelter from a storm, or a gas
station. Technology to help us deal
with unfamiliar places is very popular.
Ia
in
M
as
te
rto
n/
A
la
m
y
designed to increase its temperature, such as producing heat by the m
contractctioionsn wee knknoow aas s shivverering.g. IIf f yoyour cooree bodydy ttemempperaatuturere
abovee itits set poinnt,t, ccoollingng mmecechaaninisms are acactitivavated.d. YYou sweaat, anand
evapooraating moissture cooools yyouourr skkinin. BlBlooood isis ddiviveerteedd to tthehe ooutter p
oof the bbodody,y, lleadidingng tto a a flflushheded apppeaeararancnce..
Motivation begins with a stimulus, from either the internal or ext
environmnment of the orgganism, that servvees as a cue for momotivated beha
Stimulli tthatt aarere iimpmporortaantt tto susurvrvivivala ,, ssuchch aass ththe e prpresesenenence of a pred
or a defieficit inin bb dodyy flufluidids, ggeneeraatee aarouousaal annd d teensnsioion, a state frequ
referreded ttoo aas drdrivive (H(Hulull, 119943)). Beining inin a ddriveve sstatatete pprropels the orga
into some sort of action related to the stimulus wwhhetethher that means
ise, whether thhat is foood,
r fromm aa ststorm, oor a gaas
nologgyy to hheelp uus deaall
ar places is very popularar.
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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WHAT DOES IT MEAN TO BE MOTIVATED? 291
rewards can have negative effects on intrinsic motivation. For example, if a
child who enjoys reading suddenly gets paid for each book completed, the
childs enjoyment of reading might decrease because the motivation shifts
from intrinsic (the love of reading) to extrinsic (the love of reward money;
DeCharms, 1968).
Psychologists have studied a wide range of motives, ranging from the
mostly physical motives of temperature control and thirst to the much
more cognitive and social motives to achieve and affiliate with others. We
will explore this range by discussing some specific motives in detail, includ-
ing hunger, sexuality, achievement, and affiliation. After discussing these
examples, we will examine the ways human beings set priorities when faced
with competing motives.
S
on
ia
M
os
ko
w
itz
-G
lo
be
P
ho
to
s,
In
c.
/N
ew
sc
om
What students
were paid for
Location
Grade level
participating
How much
Average
student earned
Study
size*
Results
DALLAS CHICAGO WASHINGTON NEW YORK CITY
Positive
Rewarding five different
actions, including
attendance and
behavior, seemed to
improve reading skills.
No Effect
Paying kids for
higher test scores
did not lead to more
learning or better
grades or any
measureable changes.
Mixed
Kids cut fewer
classes and got
slightly better grades.
Standardized test
scores did not change.
Very Positive
Paying kids to
read dramatically
boosted reading-
comprehension scores.
Second-graders Ninth-graders Sixth-, seventh-,
and eighth-graders
Fourth- and
seventh-graders
Reading Grades Various Test scores
$2 per book
$50 for As
$35 for Bs
$20 for Cs
Up to $100 every
two weeks
$25 (fourth-graders) to
$50 (seventh-graders) per test
$13.81 $695.61 $532.85 $139.43 (fourth-graders)
$231.55 (seventh-graders)
1,780 from
22 schools
4,396 from
20 schools
3,495 from
17 schools
8,320 from
63 schools
*Not including control groups A combination of metrics that varied from school to
school but always included attendance and behavior
Economist Roland Fryer Asks Whether Incentives Work. Harvard economist Roland Fryer
overcame a very tough childhood in Daytona, Florida, to become the youngest tenured African
American professor in the history of Harvard University. Drawing on his personal experiences, Fryer
experimented with different incentives for a variety of school-related behaviors. His results suggest
that the relationships among intrinsic rewards, extrinsic rewards, and behavior can be quite complex.
Although previous research has shown that extrinsic rewards can undermine intrinsic motivation, it
is important to remember that this result occurs only when behavior is intrinsically motivated in the
first place. If children do not intrinsically enjoy reading, Fryer suggests paying them to read might
work. Unfortunately, Fryer has been the target of death threats for suggesting this simple solution to
illiteracy.
F i g u r e 7 . 1
C
en
ga
ge
L
ea
rn
in
g
20
13
hat students
ere paid for
Locatioon DALLAS HICHIHICAGCAGCAGOO WASWASHHHINGTOGTT N NEW YORK CITY
Reading Grades Various Test scores
mented with differennt incentives for a variety of school related behaviors. His results suggest
e relationshipss amongng intrinsic rewardss,, exextrtrininsic rerewawardrds, andnd behavioorr can bee qquiuitete ccomplexex.
gh prereviviououss resesearch hhas shown that t exxttrinsic rewwarrds can unndeermrmine inntrinnssic c motivation, iit
ortantnt ttoo reememmberr tthahat thhisi result oocccurs only whhen bbehehavioor iis iintntrir nsiccallly mottivivatateded in ththee
ace. If children do not iinntrinssici ally enjnjoyoy reading, FFryyer suggesstss payyiningg tthemm ttoo readd mmighht
UnUnfortuunately, Fryerr hhas beeenn the targetet ooff dedeaath ththrereatatss for susuggestingng this sisimpmplele ssololuttioion to
cycy.
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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Chapter 7 | THE FEELING MIND: MOTIVATION AND EMOTION292
ost university counsel-
ing websites offer advice
to students about avoid-
ing procrastination. These sites
typically describe procrastination
in very negative terms. Procrastina-
tors are seen as less capable, poorly
motivated, more anxious, low in
self-esteem, and high in anxiety and
stress (Ferrari, 1991). At the same
time, psychologists report that pro-
crastination is far from rare. About
70% of college students report some
procrastination, and 20% procras-
tinate habitually (Schouwenburg,
1995). In contrast to the negative
stereotypes of the procrastinator,
better students often report more
procrastination, and students who
are farther along in their academic
careers report more procrastination
than students just starting out (Fer-
rari, 1991). How can we reconcile
these divergent views of procrasti-
nation in light of our discussion of
motivation?
Why Do We Procrastinate?
Thinking
Scientifically
M
Human beings consume a wide range
of diets, from the nearly all-meat diet
of the traditional Inuit cultures to the
vegan diet.
d
bi
m
ag
es
/A
la
m
y
Ve
ga
n
Fo
od
P
yr
am
id
W
an
da
E
m
ba
r,
w
w
w
.v
eg
an
pe
ac
e.
co
m
.
U
se
d
w
ith
p
er
m
is
si
on
.
Hunger and
Eating
Hunger is a very complex motive. In comparison to
the regulation of body temperature through pro-
cesses like sweating or shivering, the reduction of
hunger through eating is much more heavily influenced by emotion, learn-
ing, and culture. Human beings take in a remarkable variety of nutrients.
The traditional diet of the Inuit people living in Arctic regions contains
very little plant material, whereas vegans strictly adhere to a diet that con-
tains no animal material at all.
gs ccononsus me a wide raannge
mm the nneearly all-meat ddiei t
onnaal Inuit cculturees s to theh
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WHAT DOES IT MEAN TO BE MOTIVATED? 293
The Sensation of Hunger We
respond to combinations of
external and internal cues that
make us feel hungry. External
cues for hunger may include
time of day, the sights and
smells of favorite foods, admo-
nitions that we should clean
our plates, or the social set-
tings in which food is pre-
sented. These external cues
may encourage us to eat when
our bodies do not need nutri-
ents or to eat more food than
we require. Individuals who
are relatively less responsive to
external cues are less likely to have trouble maintaining a healthy weight.
Internal cues for hunger are generated when our bodies are genuinely
short on nutrients. Note that short on nutrients applies to the mainte-
nance of current, not necessarily ideal weight. A morbidly obese person is
likely to feel as hungry as a very thin person when sufficient nutrients are
not available to maintain the status quo.
Psychologist Walter Cannon provided an early hypothesis about hun-
ger cues. Cannon believed that stomach contractions were an important
component in the detection of hunger. He persuaded his colleague A. L.
Washburn to swallow a balloon attached to an air pump (Cannon & Wash-
burn, 1912). The balloon allowed Washburns stomach contractions to be
monitored. Although Washburns feelings of hunger (as expressed by his
pushing a telegraph key, since he couldnt talk with a tube down his throat)
correlated with his stomach contractions, these signals do not tell the
whole story. Patients who have had their stomachs surgically removed still
experience a sense of hunger in the general region where the stomach used
to be. Most of us start eating long before our stomachs begin to growl, indi-
cating that additional types of signaling must be at work (see Figure 7.2).
Is it possible that procrastination
can be both adaptive and maladap-
tive? It appears so (Schraw, Wadkins,
& Olafson, 2007). Students do report
negative consequences of procrasti-
nation, particularly on term papers,
but also see some advantages. Pro-
crastination may be viewed as a way
of prioritizing unrealistic amounts
of work. Consequently, the most
successful procrastinators plan the
terms work out carefully in advance.
Working under a tight deadline
increases motivation for some people
and provides a rationale for forgoing
other activities, such as socializing
with friends. As stressful as such
work may be, completion of a task is
followed by immediate relief, which
may in turn serve as a potent reward
for procrastinating.
In light of these findings, should
we continue to try to minimize pro-
crastination? If so, how would we
do this? Part of the answer lies in
assessing the reasons students give
for procrastinating: managing time
(social and work activities take pre-
cedence over schoolwork for most
students), avoiding boredom, and
working more efficiently. It is likely
that once procrastination no longer
produces the desired results (i.e., the
stress becomes too much or perfor-
mance suffers), the student will be
motivated to change.
B
et
tm
an
n/
C
O
RB
IS
Walter Cannon. Walter Cannon
and his assistant, A. L. Washburn,
performed one of the earliest
experiments on the relationship
between stomach contractions
and feelings of hunger. The large
waves at the top were Cannons
recordings of Washburns stomach
contractions, and the smaller
waves at the bottom represent
Washburns key taps indicating
hunger. Although these two events
are correlated, there is much
more to hunger than a growling
stomach.
F i g u r e 7 . 2
C
en
ga
ge
L
ea
rn
in
g
20
13
y to feel as hunggry as a very thin person when sufficient nutrients are
available to mmaintntain the statusus qquouo.
sycchhologgist Waltter Cannonn pprovided anan eearlyy hhypypotthhesisis about hun-n-
ues. CaC nnon bbelieieveved d thatt sttomach ccoontracttioons s wew rre aann impoportanant t
ppoonennt in the ddetectitioon of huhungngerer. HeHe pperersuadaded hhisis collleleagagueue AA.. L.
hhbuburrn to swallow w aa bballoon attached to an air pump (Cannon & Wash-
, 191212)). ThThe e baballlloooon allowedd WWashburns stomach contractiionons to be
itoredd. AAltl hohougugh WWashburns feelilingngss ofo hhununggerr (a(as exxprpreesssed d byby hhiss
ing a tellegraph key, since he coouldndntt t lalkk wiwithth a tuube ddownwn hhiss thrhroaat))
elated with his stomach conttractionsns, thhesese siiggnals do nott tellll thhe
e story Patients who have had their stomachs surgically removed still
performed one of the ear
experimementntss onon thee rrelelatatioio
betwweeeenn stomach ccontrac
ana d ffeeelingsgs off hunngerer.. ThTh
wwavees s atat the top wwerre Ca
rereccordiningsgs ooff WWashhbuburnrnss
contractions, and the sma
waves at the bottom repr
WaWashshbubuuurnrnnns key taps indic
huhungngeer. Although these tw
araree cocorrelated, there is mu
momorere tto hunger than a gro
h
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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Chapter 7 | THE FEELING MIND: MOTIVATION AND EMOTION294
A likely candidate for an additional hunger cue is a low level of circulat-
ing sugars, particularly glucose. Glucose concentrations in the blood are
highest just following a meal. As glucose levels drop over time, a person
begins to feel hungry again. Glucose levels are intimately connected with
levels of the hormone insulin. Insulin, released by the pancreas, moves
circulating glucose from the blood into cells awaiting nutrients. Typically,
glucose and insulin levels are positively correlated. Right after a meal, both
are high. Glucose levels rise as glucose is extracted from the food that has
been consumed, and insulin is high because its release is triggered by the
anticipation and consumption of food. As time goes by without more food,
glucose moves from the blood into other tissues, and insulin is no longer
released, leading to lower levels of both substances in the blood. These
lower levels of glucose and insulin should signal the need for more food
(see Figure 7.3).
This is an overly simplistic conclusion, however. You may know people
with diabetes mellitus who must check the glucose levels in their blood
several times per day, as high levels of circulating glucose can harm many
organs. High glucose levels occur in untreated diabetes due to either a lack
of insulin production (Type I diabetes) or the bodys resistance to insulin
(Type II diabetes). Without sufficient insulin activity, circulating glucose is
unable to move out of the blood into the cells that need nutrients. If hun-
ger results from low levels of circulating glucose, we would expect people
with untreated diabetes to not feel very hungry, but this is definitely not
the case. Most patients with high blood sugar report feeling hungry all the
time. This makes sense when you consider that their cells are starving due
to their inability to obtain glucose from the blood. It is more accurate to say
that the amount of glucose that is available to cells is an indicator of hunger
(Mayer, 1955). Hunger will result whenever cells are unable to obtain the
glucose they require.
Hunger also occurs in response to low levels of stored fats (Kennedy,
1953). If you maintain a healthy weight, you are carrying sufficient body
glucose A type of sugar that plays an
important role in hunger levels.
120
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30 0 30
Time (min)
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Healthy control
Type 2 diabetes
120
Insulin Release Is Reduced in
Type 2 Diabetes. Following a
meal (time 0), a healthy person
experiences a large spike in
insulin levels. In contrast, a
person with Type 2 diabetes has
a much slower and less dramatic
release of insulin. The person
with diabetes will not be able to
move glucose out of the blood
into cells requiring nutrients.
The appetite-suppressing action
of insulin will be less effective,
and the person with diabetes
will remain hungry.
F i g u r e 7 . 3
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highest just following a meal. As glucose levels drop over time, a pe
begins tto o fefeele hunungrgryy aggaiain.n Glulucosese llevevelels are inintimatetelyly ccononneectcteded
levelss oof the hoormmono e ininsusulil n. Insnsuulin,, releasseded bby ththee pap ncreasas,, mm
circullatating glucosose ffromm tthee bbloloodd iintn o cec llls awwaiaitiingng nnutriiene ts. TyTy ipi
gglucose e anand d iinsuulilinn lelevelsls are ppoositivvelely y cocorrrelelaated. RRighhtt afafteterr a memealal,,
are high. Glucose levels rise as glucose is extracted from the food tha
been cconnsumed, and insulin is highg bececause its release iis s triggered b
anticipapattionn aandnd cconnsusummptitionon oof f fofoodod. AAs timmee gogoeses bby y wiwiwiitthout more f
glucosee moveves s ffromm tthehe bbloood inntoo ootheher tiissueues, aandnd insulin is no lo
releaseded, leleaddiningg too llowowerr llevelelss off bototh susubssttancnceses iinn the blood. Th
lower levels of glucose and insulin should signall ththee need for more
9781305461994, Discovering Psychology: The Science of the Mind, Cacioppo/Freberg – Cengage Learning. All rights reserved. No distribution allowed without express authorization.
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WHAT DOES IT MEAN TO BE MOTIVATED? 295
fat to survive five to six weeks of total starvation.
Obviously, the heavier the person, the longer he
or she can survive without food. One patient sur-
vived a total fast of 382 days, during which time
his weight dropped