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Transcript of 1
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PowerPoint®
Presentationby Jim Foley
© 2013 Worth Publishers
Chapter 1ThinkingCritically
withPsychological
Science
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Critical thinking refersto a more careful style offorming and evaluatingknowledge than simplyusing intuition.
In addition to the scientifc
method, critical thinking willhelp us develop moreeective and accurate waysto gure out what makespeople do, think, and feel the
things they do.
psychological science…does this mean “criticize”?
Why do I needto work on mythinking? Can’tyou just tell mefacts about psychology?
•
The brain isdesigned forsurviving andreproducing, butit is not the besttool for seeing
reality! clearly.• To improve ourthinking, we willlearn to catchourselves in somecritical thinking
errors.
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en our natura t n ngstyle ails!
"indsight#ias!
"I knew it all
along.#
$%erconfdence error!"I am sure I
am correct.# The coincidenceerror, or
mistakenlypercei%ing
order inrandom e%ents$
"The dice mustbe %ed becauseyou rolled threesi%es in a row.#
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"indsight“&ias”
The mind builds itscurrent wisdom aroundwhat we have alreadybeen told. &e are"biased# in favor of oldinformation.
For e%ample, we maystay in a badrelationship because it
has lasted this far andthus was "meant to be.#
Why call it“bias”?
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$%erconfdence 'rror 1!
erformance &e are much too certainin our 'udgments.
&e overestimate ourperformance, our rate ofwork, our skills, and ourdegree of self(control.
$%erconfdence 'rror (!
!ccuracy
&e overestimate theaccuracy of ourknowledge. )eople
are much morecertain than theyare accurate.
*vercondence is aproblem ineyewitness
testimony. *vercondence is
also a problem ontests. If you feelcondent that youknow a concept, try
e%plaining it tosomeone else.
Test for this$ "how longdo you think it takesyou to+# e.g. "'ustnish this one thing I!m
doing on the computerbefore I get to work#-
/nd your unscramblingspeed
"#$"%!&"%'()
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and o%eruse our intuition)
*rom an e%olutionary
perspecti%e!"indsight#ias
might be anoshoot ofour useful
habit ofanaly0ing anevent andtrying togure out
why itoccurred.
$%erconfdence errormight help
us lead otherpeople1
certaintybuildscondence in
followersmore thanaccuracy
does.
Percei%ingorder helps
us make
predictions1we 'ust needto test these
and notoverdo it.
$ometimes ourintuition gi*es
the rightanswer+ which
makes us trustit e*en more,
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+aking our ideas moreaccurate #y
#eing scientifc&hat did "/ma0ing2andi# do about theclaim of seeing auras3e developed a testableprediction, which would
support the theory if itsucceeded.Which it didnot,
The aura(readers were
unable to locate theaura around 2andi!sbody without seeing2andi!s body itself, sotheir claim was not
supported.
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4ut to guide you, you!llneed a scientic
/TTIT567.
ay, owdo - goa#out#eing
scientifc)
Is there
math?-esttubes?
8ou!ll need tobe systematic.
S i if i d
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Scientifc .ttitude Part 1!Curiosity
"ypothesis!
9uriosity, ifnot guided bycaution, canlead to thedeath of
felines and
perhapshumans.
/efnition!always asking new:uestions
“-hat beha*ior I’m noticing in that
guy. is that common to all people?'r is it more common when understress? 'r only common for males?”
S i if . i d P (
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Scientifc .ttitude Part (!Skepticism
/efnition! not accepting a fact! as truewithout challenging it1 seeing
if facts! can withstandattempts to disprove them
$kepticism+ like curiosity+ generates/uestions0 “Is there another e1planation
for the beha*ior I am seeing? Is there a problem with how I measured it+ or how Iset up my e1periment? 2o I need tochange my theory to 3t the e*idence?”
S i if . i d P 0
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Scientifc .ttitude Part 0!"umility
"umility reersto
seeking the truth
rather thantrying to beright; a scientist
needs to be
able to acceptbeing wrong.
“Whatmatters is
not myopinion oryours+ butthe truthnature
re*eals inresponse to
our/uestioning,”
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Criticalthinking!
analy0inginformation todecide if it
makes sense,rather than
simply
accepting it.oal! gettingat the truth,
even if it meansputting aside
your own ideas.
;ook forhidden
assumptions anddecide if
you agree.
;ook for
hidden#ias,politics,
values, orpersonalconnectio
ns.
)ut aside
your ownassumptions andbiases,
and lookat the
evidence.
<ee ifthere wasa =aw inhow the
information was
collected.
9onsider if
there areotherpossible
e%planations for thefacts orresults.
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%etting to the truth0
The Scientifc +ethod
The scientic method is theprocess of testing our ideasabout the world by$
If the data doesn!t t our ideas, then wemodify our ideas, and test again.
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Scientifc+ethod! Toolsand oals
re%ealed #y the scientifc
method!
The brain can recoverfrom massive earlychildhood braindamage.
<leepwalkers are notacting out dreams.
*ur brains do nothave accurate
memories lockedinside like video les. There is no "hidden
and unused >?percent# of our brain.
)eople often change
The #asics! Theory
3ypothesis *perational6enitions
2eplication
2esearchgoals3types!
6escription 9orrelation )rediction 9ausation
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Theory! the #ig picture
7%ample of atheory$ "/ll/636 symptomsare a reaction toeating sugar.#
/ theory, inthe language ofscience, is a set
of principles,
built onobservationsand other
veriable facts,that explains
some phenomenonand predicts itsfuture behavior.
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"ypotheses! inormedpredictions
"Testable# means thatthe hypothesis isstated in a way thatwe could makeobservations to ndout if it is true.
/ hypothesis is a testable prediction
consistent withour theory . What would be a prediction fromthe “!ll !2&2 isabout sugar”theory?
*ne hypothesis$ "If a kid gets sugar, the kid willact more distracted, impulsive, and hyper.#
To test the "/ll# part of the theory$ "/636symptoms will continue for some kids evenafter sugar is removed from the diet.#
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whypotheses!
theories can #ias our o#ser%ations
&e might select onlythe data, or theinterpretations of thedata, that supportwhat we already
believe. There aresafeguards againstthis$3ypothesesdesigned to
disconrm$perationaldefnitions
uide or makinguseulo#ser%ations!3ow can wemeasure "/636symptoms# in the
previous e%ample inobservable terms Impulsivity @ A
of timesBhourcalling outwithout raising
hand. 3yperactivity @A of timesBhourout of seat
Inattention @ Aminutes
continuously ontask before
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The ne4t3fnal step inthe scientifc
method!replication
8ou could introduce a small change in thestudy, e.g. trying the /636Bsugar test oncollege students instead of elementarystudents.
2eplicating research means
trying it again usingthe same operational
denitions of theconcepts andprocedures.
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2esearchProcess! thedepression
e4ample
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5ow that we6%e co%eredthis
We can mo%e on to this
2 h l d
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2esearch goal andstrategy!
description<trategies for gatheringthis information$Case Study!observing andgathering informationto compile an in(depthstudy of one individual5aturalistic$#ser%ation!gathering data aboutbehavior1 watching butnot interveningSur%eys and-nter%iews! havingother people report ontheir own attitudes and
/escripti%e
researchis a
systematic,objective
observation of people. The goal is
to provide aclear,
accuratepicture ofpeople!s
behaviors,thoughts,
andattributes.
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Case Study
"1amining one
indi*idual in depth 4ene3t0 can be a
source of ideas abouthuman nature in general
"1ample0 cases of
brain damage havesuggested the functionof dierent parts ofthe brain e.g. )hineasCage-
2anger0
overgenerali0ation fromone e%ample1 "he gotbetter after tapping hishead so tapping mustbe the key to healthD#
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$#ser%ing“natural”#eha%ior means
just watching(and takingnotes), and nottrying to changeanything.
This method can
be used to studymore than oneindividual, andto nd truthsthat apply to abroaderpopulation.
5aturalistic $#ser%ation
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The Sur%ey
/efnition! /method of gatheringinformation about
many people!sthoughts orbehaviors throughself(report rather
than observation. Eeys to getting useful
information$
4e careful aboutthe wordin of
Wordinge7ectsthe results you
get from asurvey can bechanged by yourword selection.
'4ample!
50 2o youha*emoti*ation tostudy hard forthis course?
50 2o you feela desire tostudy hard forthis course?
a
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apsychologysciencemistake wasmade here)
"int 81! "arry Truman won9
"int 8(!TheChicago-ribuneinter%iewed peoplea#outwhomtheywould%ote or9
"int 80!in 1:;<9
"int8;!#yphon
e9
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Why take a sample)
•
If you want to nd outsomething about men, youcan!t interview every singleman on earth.
• <ampling saves time. 8oucan nd the ratio of colors inthis 'ar by making sure theyare well mi%ed randomi0ed-and then taking a sample.
population
sampl e2andom
sampling is atechniue for
making sure thatevery individual in
a population has aneual chance of
being in your
sample.
"2andom#
means thatyour selectionof participantsis driven onlyby chance, notby any
characteristic.
i#l
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Correlation
eneral/efnition! an
observation thattwo traits orattributes arerelated to eachother thus, theyare "co#(related-
Scientifcdefnition! a measure of howclosely twofactors *arytogether , or how
well you can predicta change in one
-n a case study! The fewer hours
the boy wasallowed to sleep,
the moreepisodes ofaggression he
displayed.
. possi#leresult o manydescripti%estudies!disco*ering acorrelation -n a
naturalistic
o#ser%ation!9hildren in aclassroom whowere dressed inheavier clotheswere more likely
to fall asleepthan thosewearing lighter
clothes.-n a sur%ey! The greater the
number ofFacebook friends,
the less time wasspent studying.
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*inding Correlations!Scatterplots
)lace a dot on thegraph for each person,corresponding to the
numbers for theirheight and shoe si0e. In this imaginary
e%ample, heightcorrelates with shoe
si0e1 as height goesup, shoe si0e goes up.
" e i g h
t
Shoesi=e
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Correlation! *ace#ook and
Studying
These are two factorswhich correlate1 theyvary together .
This is a negati%e
correlation@ as onenumber goes up, theother number goesdown.
C l ti C A i t
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Correlation CoeAcient• The correlation coecient is a num#er representing the
strength and direction of correlation.•
The strength of the relationship refers to how close the dotsare to a straight line, which means one variable changese%actly as the other one does1 this number varies from ?.?? toGB( H.??.
• The direction of the correlation can be positi%e bothvariables increase together- or negati%e as one goes up, theother goes down-.
G H.?? ( H.??
)erfectpositivecorrelati
on
)erfectnegativecorrelatio
n
orelationship,
nocorrelation
%uess the Correlation Coe6cients
When scatterplots re%eal
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When scatterplots re%ealcorrelations!3eight relates to shoe si0e, but does it
also correlate to "temperamentalreactivity score# / table doesn!t showthis, but the scatterplot does.
If d
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If we nd acorrelation, what
conclusions can wedraw from it
7et’s say we 3nd thefollowing result0
there is a positi*ecorrelation betweentwo *ariables+ice cream sales+ andrates of *iolent crime&ow do we e1plainthis?
Correlation is not
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Correlation is notCausationB
")eople who=oss more
regularly haveless risk of heartdisease.#
")eople withbigger feet tendto be taller.#
If this data isfrom a survey,can we concludethat =ossingmight preventheart disease *rthat people withheart(healthyhabits also =ossregularly
6oes that meanhaving biggerfeet causes height
Thi ki iti ll # t
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Thinking critically a#outthe te4t!
If a low self(esteem test score"predicts# a high depressionscore, what have we conrmedthat low self(esteem causes orworsens depressionthat depression is bad for self(esteemthat low self(esteem may be part
of the denition of depression,and that we!re not reallyconnecting two dierent variablesat all
se es eem corre a es
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se es eem corre a eswith depression,
there are still numerous possible
causal links0
So how do we fnd out
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So how do we fnd outa#out causation) &y
e4perimentation9 '4ample!
removing sugarfrom the diet ofchildren with/636 to see if itmakes adierence
In thedepressionBself(esteem e%ample$tryinginterventions thatimprove self(esteem to see if
they cause a
'4perimenta
tion!manipulatingone factor in a
situation todetermine its
eect
Dust to clariy two
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Dust to clariy twosimilarsounding
terms…
8irst you sample+ thenyou sort 9assign:,
2andomassignment
ofparticipantsto control ore%perimentalgroups is how
you controlall variablese%cept the
one you!remanipulating.
2andomsampling ishow you get
a pool ofresearch
participantsthatrepresents
thepopulation
you!re tryingto learnabout.
l # 7
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Place#o e7ect
Place#o e7ect!experimental
e!ects that arecaused byexpectations
about theintervention
3ow do we make sure that thee%perimental group doesn!te%perience an eect becausethey e%pect to e%perience it
7%ample$ /n e%perimental groupgets a new drug while the controlgroup gets nothing, yet bothgroups improve.
%uess why,
Working with the
place#o e7ect!9ontrol groups maybe given a place#o an inactive substanceor other faketreatment in place of
the experimentaltreatment .
The control group isideally "blind# towhether they aregetting real or fake
treatment.Kany studies aredou#le#lind neither participantsnor research staknows whichparticipants are in the
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The Control roup
•
If we manipulate a variable in an e4perimental groupof people, and then we see an eect, how do we knowthe change wouldn!t have happened anyway
• &e solve this problem by comparing this group to acontrol group, a group that is the same in every wayexcept the one variable we are changing.
"1ample0 two groups of children ha*e !2&2+but only one group stops eating re3ned sugar,
4y usingrandom
assignment$randomly
selecting some
study participants tobe assigned to
the controlgroup or theexperimental
group.
3ow do makesure thecontrol groupis reallyidentical inevery way tothee%perimentalgroup
5aming the %aria#les
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The variable we are able to manipulateindependently of what the other variables
are doing is called the independent%aria#le E-FG.
L If we test the /636Bsugar hypothesis$L <ugar @ 9ause @ Independent MariableL /636 @ 7ect @ 6ependent Mariable
The variable we e%pect to e%perience achange which depends on themanipulation we!re doing is called thedependent %aria#le E/FG.
L6id ice cream sales cause a rise in violence, orvice versa There might be a confounding
variable$ temperature.
"he other variables that might have ane!ect on the dependent variable areconounding %aria#les.
5aming the %aria#les
*illing in our defnition o
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/n e4periment is a typeof research in which the
researcher carefullymanipulates a limited
number of factors (#$s)and measures the impact
on other factors (%$s).
Nin psychology,
you would belooking at theeect of thee%perimental
change IM- on a#eha%ior or
mental process
6M-.
*illing in our defnition oe 1perimentation
Correlation %s causation!
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Correlation %s9 causation!the #reasteeding3intelligence
Huestion• <tudies have found that children
who were breastfed score higheron intelligence tests, on average,than those who were bottle(fed.
• 9an we conclude that breastfeeding 9/5<7< higherintelligence
• ot necessarily. There is at leastone conounding %aria#le$genes. The intelligence testscores of the mothers might behigher in those who choosebreastfeeding.
• <o how do we deal with thisconfounding variable 3int$
e%periment.
2uling out conounding
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2uling out conounding%aria#les!
e4periment with random
assignment !n actual study in the te1t0 women were randomlyselected to be in a group in which breastfeeding was
promoted
GOpoints
Critical Thinking
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Critical Thinking
Watch out!descripti%e,naturalistic,
retrospecti%eresearchresults are
otenpresented as i
they show
causation9
.naly=ethisfctionalresult!
“Peoplewho attendpsychotherapy tend to#e more
depressedthan thea%erageperson9”
6oes this
Summary o the types o
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Comparing 2esearch +ethods
2esearch+ethod &asicPurpose "owConducted
What is+anipulated
Weaknesses
Summary o the types o2esearch
6escriptive
To observe andrecord behavior
)erformcasestudies,surveys, ornaturalistic
observations
othing o control ofvariables1single casesmay bemisleading
9orrelational To detectnaturallyoccurringrelationships1to assess howwell onevariablepredicts
another
9omputestatisticalassociation,sometimesamongsurveyresponses
othing 6oes notspecify cause(eect1 onevariablepredictsanother butthis does notmean one
causes theother7%perimental To e%plorecause(eect Kanipulateone ormorefactors1randomlyassignsome tocontrol
group
Theindependentvariables-
<ometimes notpossible forpractical orethicalreasons1results maynot generali0eto other
conte%ts
*rom data to insight!
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*rom data to insight!statistics
&e!ve done ourresearch and gathereddata.)ow what?
&e can use statistics,which are tools for
organi&ing, presenting,analy&ing, andinterpreting data.
The 5eed or Statistical
2easoning/ rst glance at ourobservations might give amisleading picture.
'4ample! Kany peoplehave a misleading pictureof what income distributionin /merica is ideal, actual,or even possible.
Malue of statistics$
H.to present a moreaccurate picture of our datae.g. the scatterplot- thanwe would see otherwise.
P.to help us reach validconclusions from our data1
statistics are a crucialcritical thinking tool.
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Tools or /escri#ing /ata-he bar graph is one simple
display method but e*en thistool can be manipulated,
'urbrandoftruckisbetter;
'urbrandoftruck isnot sodi<erent.
Why is there a di<erence in the apparent result?
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+ode
Lthe mostcommonlevelBnumberB
score
+ean
arithmetic"average#-
Lthe sum ofthe scores,divided by the
number ofscores
+edianmiddle
person!s score,or Q?th percentile-
LthenumberBlevelthat half of
people scoredabove andhalf of thembelow
+easures o centraltendency !re you looking for just ')"
)(=4"# to describe a population’s income+ height+ orage?
'ptions0
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+easures o centraltendency3ere is the mode, median, and mean
of a family income distribution. otethat this is a skewed distribution1 afew families greatly raise the mean
score.
&hy does this seesawbalance otice these
gaps
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. di7erent %iew, showingwhy the seesaw
#alances!
The income is so high for some familieson the right that 'ust a few familiescan balance the income of all thefamilies to the left of the mean.
+easures o %ariation!
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Kean
Small standardde%iation
Iarge standardde%iation
2ange$ the dierence between thehighest and lowest scores in adistribution
Standard de%iation$ a calculation ofthe average distance of scores fromthe mean
+easures o %ariation!how spread out are the scores?
k d l
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Skewed %s9 5ormal/istri#ution
Income distribution is skewed by the very rich.
Intelligence test distribution tends to form asymmetric "bell# shape that is so typical that itis called the normal cur%e9
Skewed distri#ution
5ormal cur%e
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.pplying the concepts Try, with the help of this rough drawingbelow, to describe intelligence test scores ata high school and at a college using theconcepts of range and standard deviation.
Intelligence testscores at a highschool
Intelligence testscores at acollege 1J
J
/rawing conclusions rom
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/rawing conclusions romdata!are the results useful?/fter nding a
pattern in our datathat shows adierence betweenone group andanother, we can askmore :uestions.
Is the dierencerelia#le! can weuse this result togenerali&e or topredict the futurebehavior of thebroader population
Is the dierencesignifcant! couldthe result havebeen caused byrandom' chancevariation between
3ow to achieve reliability$5on#iased sampling$ Kake surethe sample that you studied is agood representation of thepopulation you are trying to learnabout.
Consistency$ 9heck that thedata responses, observations- isnot too widely %aried to show aclear pattern.+any data points$ 6on!t try togenerali0e from 'ust a few cases,
instances, or responses.&hen have you found statisticallysignifcant dierence e.g.between e%perimental and controlgroups-&hen your data is reliable /6&hen the dierence between the