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Myers’ PSYCHOLOGY(7th Ed)

Chapter 1Thinking Critically with

Psychological Science

James A. McCubbin, PhDClemson University

Worth Publishers

The Need for Psychological Science

Psychologists, like all scientists, use the scientific method to construct

theories that organize observations and imply testable hypotheses

The Need for Psychological Science

Hindsight Biaswe tend to believe, after learning an outcome, that we would have foreseen it the “I-knew-it-all-along” phenomenon

Overconfidencewe tend to think we know more than we do

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The Need for Psychological Science

Critical Thinkingthinking that does not blindly accept arguments and conclusions

examines assumptionsdiscerns hidden valuesevaluates evidence

The Amazing Randi--Skeptic

The Need for Psychological Science

Theoryan explanation using an integrated set of principles that organizes and predicts observations

Hypothesisa testable predictionoften implied by a theory

The Need for Psychological Science

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The Need for Psychological Science

Operational Definitiona statement of procedures (operations) used to define research variablesExample-

intelligence may be operationally defined as what an intelligence test measures

The Need for Psychological Science

Replicationrepeating the essence of a research study to see whether the basic finding generalizes to other participants and circumstancesusually with different participants in different situations

Description

Psychologists describe behavior using case studies, surveys, and

naturalistic observation

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DescriptionCase Study

Psychologists study one or more individuals in great depth in the hope of revealing things true of us all

Is language uniquely human?

DescriptionSurvey

technique for ascertaining the self-reported attitudes or behaviors of peopleusually by questioning a representative, random sample of people

Random Samplea sample that fairly represents a population because each member has an equal chance of inclusion

Description

False Consensus Effecttendency to overestimate the extent to which others share our beliefs and behaviors

Populationall the cases in a group, from which samples may be drawn for a study

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Description

Description

If marbles of two colors are mixed well in the large jar, the fastest way to know their ratio is to blindly transfer a few into a smaller one and count them

Description

Naturalistic Observation

observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

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CorrelationCorrelation Coefficient

a statistical measure of the extent to which two factors vary together, and thus how well either factor predicts the other

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = +.37

Correlation

Scatterplota graphed cluster of dots, each of which represents the values of two variablesthe slope of the points suggests the direction of the relationshipthe amount of scatter suggests the strength of the correlation

little scatter indicates high correlation

also called a scattergram or scatter diagram

Correlation

Perfect positivecorrelation (+1.00)

No relationship (0.00) Perfect negativecorrelation (-1.00)

Scatterplots, showing patterns of correlations

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CorrelationHeight and Temperament of 20 Men

12345678910

11121314151617181920

80636179746962757760

64767166737063716870

75666090604242608139

48697257637530578439

SubjectHeight in

Inches Temperament SubjectHeight in

Inches Temperament

Correlation

Scatterplot of Height and Temperament

55 60 65 70 75 80 85

959085807570656055504540353025

Temperamentscores

Height in inches

CorrelationThree Possible Cause-Effect Relationships

(1)Low self-esteem Depression

(2)Depression Low self-esteem

Low self-esteem

Depression

(3)Distressing events

or biologicalpredisposition

could cause

could cause

could cause

or

or

and

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Illusory Correlation

Illusory Correlation

the perception of a relationship where none exists

Conceive Do not conceive

Adopt

Do notadopt

disconfirming evidence

confirming evidence

disconfirming evidence

confirming evidence

Two Random Sequences

Your chances of being dealt either of these hands is precisely the same: 1 in 2,598,960.

Experimentation

Experiment an investigator manipulates one or more factors (independent variables) to observe their effect on some behavior or mental process (the dependent variable) by random assignment of participants the experiment controls other relevant factors

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ExperimentationPlacebo

an inert substance or condition that may be administered instead of a presumed active agent, such as a drug, to see if it triggers the effects believed to characterize the active agent

Double-blind Procedureboth the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebocommonly used in drug-evaluation studies

Experimentation

Experimental Conditionthe condition of an experiment that exposes participants to the treatment, that is, to one version of the independent variable

Control Conditionthe condition of an experiment that contrasts with the experimental treatment serves as a comparison for evaluating the effect of the treatment

Experimentation

Random Assignmentassigning participants to experimental and control conditions by chanceminimizes pre-existing differences between those assigned to the different groups

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ExperimentationIndependent Variable

the experimental factor that is manipulatedthe variable whose effect is being studied

Dependent Variablethe experimental factor that may change in response to manipulations of the independent variable in psychology it is usually a behavior or mental process

Experimentation

Research Strategies

Design of the subliminal tapes experiment

Subliminal tape content

Self-esteem Memory

Memory

Self-esteem

Tape label

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Statistical Reasoning

Our Brand Brand BrandBrand X Y Z

100%

99

98

97

96

95

Percentagestill functioningafter 10 years

Brand of truck

Statistical Reasoning

Our Brand Brand BrandBrand X Y Z

100%9080706050403020100

Percentagestill functioningafter 10 years

Brand of truck

Statistical ReasoningMode

the most frequently occurring score in a distribution

Meanthe arithmetic average of a distributionobtained by adding the scores and then dividing by the number of scores

Medianthe middle score in a distributionhalf the scores are above it and half are below it

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Statistical ReasoningA Skewed Distribution

15 20 25 30 35 40 45 50 90 475 710

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Mode Median Mean

One Family Income per family in thousands of dollars

Statistical Reasoning

Rangethe difference between the highest and lowest scores in a distribution

Standard Deviationa computed measure of how much scores vary around the mean

Statistical Significancea statistical statement of how likely it is that an obtained result occurred by chance

Frequently Asked Questions about Psychology

Can laboratory experiments illuminate everyday life?

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Frequently Asked Questions about Psychology

Does behavior depend on ones culture?

Culture--the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next

Frequently Asked Questions about Psychology

Does behavior vary with gender?

Frequently Asked Questions about Psychology

Why do psychologists study animals?Is it ethical to experiment on animals?Is it ethical to experiment on people?

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Frequently Asked Questions about Psychology

Is psychology free of value judgments?

Frequently Asked Questions about Psychology

Is psychology potentially dangerous?