Psychology as a Psychology as a ScienceScience In this discussion we will explore:In this discussion we will explore:

– limits of common senselimits of common sense– science - a method for understandingscience - a method for understanding– methods of sciencemethods of science

descriptiondescription correlationcorrelation experimentationexperimentation

– evaluating data with statisticsevaluating data with statistics– sources of error and bias in researchsources of error and bias in research

How do we know How do we know things?things? ‘‘We Just Know It’ – Intuition or We Just Know It’ – Intuition or

Common SenseCommon Sense

OROR Tried and True ScienceTried and True Science

Can we trust our intuition?Can we trust our intuition?(Activity - add)(Activity - add)

Science vs. Common Science vs. Common SenseSense

Why don’t we rely on Why don’t we rely on intuition (common sense)?intuition (common sense)?

(Activity – Research/1(Activity – Research/1stst Brain Games clip 0-8:18) Brain Games clip 0-8:18)

1. Hindsight Bias – tendency to 1. Hindsight Bias – tendency to believe, after learning an outcome, believe, after learning an outcome, that one would have foreseen it.that one would have foreseen it.

To find out something has happened, To find out something has happened, makes it inevitable – I Knew It All Along makes it inevitable – I Knew It All Along PhenomenonPhenomenon

(Activity-%)(Activity-%)

Why don’t we rely on Why don’t we rely on intuition (common intuition (common sense)?sense)? 2. Overconfidence – we tend to 2. Overconfidence – we tend to

think we know more than we dothink we know more than we do Humans are usually more confident Humans are usually more confident

than correct.than correct.

Try these anagrams:Try these anagrams: WREATWREAT

ETRYNETRYN

GRABEGRABE

OCHSAOCHSA

Why don’t we rely on Why don’t we rely on intuition (common intuition (common

sense)?sense)?WaterWater

EntryEntry

BargeBarge

ChaosChaos

Once people know the target word, Once people know the target word, hindsight makes the words obvious. hindsight makes the words obvious. We believe that we should have seen We believe that we should have seen the solution in a shorter period of time.the solution in a shorter period of time.

(2(2ndnd Brain Games clip @14:37) Brain Games clip @14:37)

Science vs. Common Science vs. Common SenseSense Common sense and intuition often Common sense and intuition often

tell us about psychologytell us about psychology– e.g., suppose a study tells us that e.g., suppose a study tells us that

‘separation weakens romantic attraction’‘separation weakens romantic attraction’– common sense may tell us - “out of sight, common sense may tell us - “out of sight,

out of mind”out of mind”– or common sense may say the opposite - or common sense may say the opposite -

“absence makes the heart grow fonder”“absence makes the heart grow fonder”

Common sense can be inconsistent Common sense can be inconsistent and based on hindsightand based on hindsight

Science vs. Common Science vs. Common SenseSense Science helps build explanations that Science helps build explanations that

are consistent and predictive rather are consistent and predictive rather than conflicting and postdictive than conflicting and postdictive (hindsight)(hindsight)

Science is based onScience is based on– knowledge of factsknowledge of facts– developing theories developing theories – testing hypothesestesting hypotheses– public and repeatable procedurespublic and repeatable procedures

Scientific Scientific Inquiry/ResearchInquiry/Research Facts are what need to be explainedFacts are what need to be explained

– objective - viewable by othersobjective - viewable by others– based on direct observationbased on direct observation– reasonable observers agree are truereasonable observers agree are true

Theory is a set of ideas thatTheory is a set of ideas that– organizes factsorganizes facts– makes predictions about observations (new facts)makes predictions about observations (new facts)

Hypothesis Hypothesis – prediction about new facts (often implied by prediction about new facts (often implied by

theory)theory)– can be verified or falsifiedcan be verified or falsified

Scientific Scientific Inquiry/ResearchInquiry/Research

As a check on their bias, psychologists As a check on their bias, psychologists report their findings with –report their findings with –

Operational Definitions (of Concepts):Operational Definitions (of Concepts):a statement of the procedures used to define a statement of the procedures used to define

research variablesresearch variables

Operational Definitions allow others to Operational Definitions allow others to replicate the study (repeating the essence replicate the study (repeating the essence of the study to get similar results). of the study to get similar results).

Research Methods in Research Methods in PsychologyPsychology

Setting - field vs. laboratorySetting - field vs. laboratory Methods of data collectionMethods of data collection

– self-report vs. observationalself-report vs. observational

Research plan or designResearch plan or design– descriptivedescriptive– correlationalcorrelational– experimentalexperimental

Descriptive ResearchDescriptive Research Describes a set of factsDescribes a set of facts DoesDoes notnot look for relationships look for relationships

between factsbetween facts DoesDoes notnot predict what may influence predict what may influence

the factsthe facts May or may not include numerical dataMay or may not include numerical data Example: measure the % of new students Example: measure the % of new students

from out-of-state each year since 1980from out-of-state each year since 1980

Descriptive ResearchDescriptive Research

Types of descriptive research Types of descriptive research 1.1. Case StudyCase Study

In-depth study of one individualIn-depth study of one individual

2.2. Naturalistic ObservationNaturalistic ObservationRecorded observation of people or Recorded observation of people or animals in their natural environment – animals in their natural environment – focus on a specific behaviorfocus on a specific behavior

3.3. SurveySurvey

SurveysSurveys

Wording Effect - need to watch for Wording Effect - need to watch for bias, order of wording, too generalbias, order of wording, too general

(attractiveness, intelligence)(attractiveness, intelligence) SamplingSampling

– False Consensus Effect – tendency to False Consensus Effect – tendency to overestimate other’s agreement with overestimate other’s agreement with usus

Creates the need for a representative Creates the need for a representative sample of the populationsample of the population

Surveys Surveys

Sampling Cont’d.Sampling Cont’d.– Population – all the cases in a group, Population – all the cases in a group,

from which samples may be drawn from which samples may be drawn for a study for a study (e.g. study on (e.g. study on studying habits – population would studying habits – population would be be allall students) students)

– Random Sample – sample in which Random Sample – sample in which every person in a group has equal every person in a group has equal chance of participatingchance of participating

Descriptive ResearchDescriptive Research

Pros vs. ConsPros vs. Cons

Correlational ResarchCorrelational Resarch

Collects a set of facts organized Collects a set of facts organized into two or more categoriesinto two or more categories– measure parents disciplinary stylemeasure parents disciplinary style– measure children’s behaviormeasure children’s behavior

Examines the relationships Examines the relationships between 2 or more categories between 2 or more categories

e.g., more democratic parents have e.g., more democratic parents have children who behave betterchildren who behave better

Correlational ResearchCorrelational Research

Correlation CANNOT prove Correlation CANNOT prove causationcausation– Do democratic parents produce better Do democratic parents produce better

behaved children?behaved children?– Do better behaved children encourage Do better behaved children encourage

parents to be democratic?parents to be democratic?

May be an unmeasured common May be an unmeasured common factorfactor – e.g., good neighborhoods produce e.g., good neighborhoods produce

democratic adults and well behaved childrendemocratic adults and well behaved children

Correlational ResearchCorrelational Research

Scatterplots – graphed cluster of Scatterplots – graphed cluster of dots, each of which represents dots, each of which represents the values of two variablesthe values of two variables– See pg. 27 for examplesSee pg. 27 for examples

Correlation Coefficient – a Correlation Coefficient – a statistical measure of relationshipstatistical measure of relationship– Statistical measure of the extent to which Statistical measure of the extent to which

two factors vary together, and thus of two factors vary together, and thus of how well either factor predicts the other.how well either factor predicts the other.

Correlational ResearchCorrelational Research

Direction of a Direction of a CorrelationCorrelation

(slope of the points)(slope of the points) Positive Positive Correlation – as one Correlation – as one

variable goes up, the other variable goes up, the other variable tends to go up (so as one variable tends to go up (so as one goes down, the other goes down) goes down, the other goes down) – max. +1.00– max. +1.00

NegativeNegative Correlation – as one Correlation – as one variable goes up, the other tends variable goes up, the other tends to go down, the inverse is also to go down, the inverse is also true – min. -1.00true – min. -1.00

No No Correlation – correlation is 0.0Correlation – correlation is 0.0

Strength of CorrelationStrength of Correlation

(amount of scatter)(amount of scatter) The higher the correlation The higher the correlation

coefficient is (without regard to coefficient is (without regard to sign) the stronger the correlation sign) the stronger the correlation is.is.

The stronger the correlation is, the The stronger the correlation is, the better one variable can predict the better one variable can predict the other.other.

Correlational ResearchCorrelational Research

Correlations make visible relationships Correlations make visible relationships that we might otherwise miss.that we might otherwise miss.

They also restrain our “seeing” They also restrain our “seeing” relationships that actually do not relationships that actually do not exist – illusory correlations – exist – illusory correlations – perception of a relationship where perception of a relationship where none exists none exists

(e.g., superstitious beliefs)(e.g., superstitious beliefs)

Believe – likely to notice and recall Believe – likely to notice and recall

Perceiving Order Perceiving Order

As humans we want to make sense of As humans we want to make sense of our world, so we look for our world, so we look for meaningful patterns.meaningful patterns.

Prob – Random sequences often don’t Prob – Random sequences often don’t look random – leads to illusory corr.look random – leads to illusory corr.

If someone flipped a coin six times, which If someone flipped a coin six times, which of the following sequences of H and T of the following sequences of H and T would be most likely?would be most likely?

HHHTTTHHHTTT HTTHTHHTTHTH HHHHHHHHHHHH

Correlational Research Correlational Research

A little note about correlation – A little note about correlation –

CORRELATION CORRELATION

DOES NOT PROVE DOES NOT PROVE CAUSATION!!CAUSATION!!

ExperimentsExperiments

Direct way to test a hypothesis Direct way to test a hypothesis about a about a cause-effectcause-effect relationship relationship between variablesbetween variables

One variable is controlled by the One variable is controlled by the experimenterexperimenter– e.g., democratic vs. authoritarian classroome.g., democratic vs. authoritarian classroom

The other is observed and The other is observed and measuredmeasured– e.g., cooperative behavior among studentse.g., cooperative behavior among students

Experimental VariablesExperimental Variables

Independent variableIndependent variable – the the controlledcontrolled factor in an experiment factor in an experiment

– what the experimenter manipulates– what the experimenter manipulates– hypothesized to cause an effect on hypothesized to cause an effect on

another variableanother variable Dependent variableDependent variable

– the the measuredmeasured facts/data facts/data – hypothesized to be affectedhypothesized to be affected

Independent VariableIndependent Variable

Must have at least two levelsMust have at least two levels– categories - male vs. femalecategories - male vs. female– numeric - ages 10, 12, 14numeric - ages 10, 12, 14

Simplest is experimental vs. controlSimplest is experimental vs. control– experimental condition gets treatment experimental condition gets treatment

(e.g., gets the new drug)(e.g., gets the new drug)– control condition does notcontrol condition does not

(e.g., gets the placebo)(e.g., gets the placebo)(created when using a double-blind (created when using a double-blind

procedure)procedure)

Experimental DesignExperimental Design

Levels may differ between or within Levels may differ between or within peoplepeople

Within-subject experiment - different Within-subject experiment - different levels of the independent variable are levels of the independent variable are applied to the same subjectapplied to the same subject

Between-groups experiment - different Between-groups experiment - different levels of the independent variable are levels of the independent variable are applied to different groups of subjects applied to different groups of subjects

Sources of BiasSources of Bias

Confounding Variables -Confounding Variables -– Any variable besides the Any variable besides the

independent variable that independent variable that affects the dependent variable affects the dependent variable in one group but not the other.in one group but not the other.

(e.g., placebo takes a study skills (e.g., placebo takes a study skills seminar, non random seminar, non random

assignment)assignment)

Experimental DesignExperimental Design Random sample - every member of the Random sample - every member of the

population being studied should have population being studied should have an equal chance of being selected for an equal chance of being selected for the studythe study

Random assignment - every subject in Random assignment - every subject in the study should have an equal chance the study should have an equal chance of being placed in either the of being placed in either the experimental or control group experimental or control group

Randomization helps avoid false resultsRandomization helps avoid false results

Experimental DesignExperimental Design

ValidityValidity – extent to which a test – extent to which a test measures or predicts what it is measures or predicts what it is supposed tosupposed to

Internal Internal ValidityValidity – – controlled controlled for confounding variables (if for confounding variables (if random assignment is violated, random assignment is violated, can destroy internal validity)can destroy internal validity)

ExternalExternal Validity – Validity – generalizability (if random sample generalizability (if random sample is violated, can destroy external is violated, can destroy external validity)validity)

Sources of BiasSources of Bias

Observer-expectancy effectObserver-expectancy effect– researcher has expectations that researcher has expectations that

influence measurements influence measurements Subject-expectancy effectSubject-expectancy effect

– subject knows design and tries to subject knows design and tries to produce expected resultproduce expected result

BlindingBlinding – minimize expectancy by removing minimize expectancy by removing

knowledge about experimental knowledge about experimental conditionsconditions

BlindingBlinding

Single-blind study - when Single-blind study - when subjects are kept uninformed as subjects are kept uninformed as to the treatment they are to the treatment they are receivingreceiving

Double-blind study - when both Double-blind study - when both subjects and experimenter are subjects and experimenter are kept uninformed about aspects kept uninformed about aspects of the study that could lead to of the study that could lead to differential expectationsdifferential expectations

Double Blind Double Blind ProceduresProcedures

Double Blind Procedures allow Double Blind Procedures allow researchers to check for a researchers to check for a treatment’s actual effects apart treatment’s actual effects apart from the from the placebo effectplacebo effect – –

- experimental results caused - experimental results caused by expectations alone; such as a by expectations alone; such as a research participants’ enthusiasm research participants’ enthusiasm for it or the healing power of belief for it or the healing power of belief

Research SettingsResearch Settings LaboratoryLaboratory

– a setting designed for researcha setting designed for research– provide uniform conditions for all subjectsprovide uniform conditions for all subjects– permits elimination of irrelevant factorspermits elimination of irrelevant factors– may seem artificialmay seem artificial

Field researchField research– behavior observed in real-world settingbehavior observed in real-world setting– poor control over conditions poor control over conditions – measures may be more representative of realitymeasures may be more representative of reality

Data-Collection Data-Collection MethodsMethods

Self-report - procedures in which Self-report - procedures in which people rate or describe their own people rate or describe their own behavior or mental statebehavior or mental state– questionnaires questionnaires – rating scales rating scales

on a scale from 1 to 7 rate your opinion of …on a scale from 1 to 7 rate your opinion of …

– judgements about perceptionsjudgements about perceptions on a scale from 1 to 100 how hot is ...on a scale from 1 to 100 how hot is ...

Data-Collection Data-Collection MethodsMethods

Observational methods - Observational methods - researchers directly observe and researchers directly observe and record behavior rather than record behavior rather than relying on subject descriptionsrelying on subject descriptions– naturalistic observation - researcher naturalistic observation - researcher

records behavior as it occurs naturallyrecords behavior as it occurs naturally– tests - researcher presents stimuli or tests - researcher presents stimuli or

problems and records responsesproblems and records responses

Data-Collection Data-Collection MethodsMethods Cross-Sectional Studies –study in Cross-Sectional Studies –study in

which subjects of different ages which subjects of different ages are compared at a given timeare compared at a given time

Longitudinal Studies – study in Longitudinal Studies – study in which subjects are followed and which subjects are followed and periodically reassessed over a periodically reassessed over a period of timeperiod of time

Data-Collection Data-Collection MethodsMethods Meta-Analysis – combine and Meta-Analysis – combine and

analyze data from many analyze data from many studies; it determines how studies; it determines how much of the variance in much of the variance in scores across all studies can scores across all studies can be explained by a particular be explained by a particular variablevariable