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Thinking Critically with Psychological

Science

Chapter 1

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Thinking Critically with Psychological Science

The Need for Psychological Science The limits of Intuition and

Common Sense

The Scientific Attitude

The Scientific Method

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Thinking Critically …

Description The Case Study

The Survey

Naturalistic Observation

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Thinking Critically …

Correlation Correlation and Causation Illusory Correlation Perceiving Order in Random

Events

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Thinking Critically …

Experimentation Exploring Cause and Effect

Evaluating Therapies

Independent and Dependent Variables

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Thinking Critically …

Statistical Reasoning Describing Data

Making Inferences

FAQs About Psychology

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Impression of Psychology With hopes of satisfying curiosity, many

people listen to talk-radio counselors and psychics to learn about others and themselves.

Dr. Crane (radio-shrink)

http://ww

w.nbc.com

http://ww

w.photovault.com

Psychic (Ball gazing)

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The Need for Psychological Science

Intuition & Common Sense

Many people believe that intuition and common sense are enough to bring forth

answers regarding human nature.

Intuition and common sense may aid queries, but they are not free of error.

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Limits of Intuition

Personal interviewers may rely too much on their “gut feelings” when

meeting with job applicants.

Taxi/ G

etty Images

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Errors of Common Sense

Try this !

Pennies in a cup

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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Hindsight Bias is the “I-knew-it-all-along” phenomenon.

After learning the outcome of an event, many people believe they could have

predicted that very outcome. We only knew the dot.com stocks would plummet after

they actually did plummet.

Hindsight Bias

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OverconfidenceSometimes we think we know more than we actually know.

Anagram

BARGEGRABE

ENTRYETYRN

WATERWREATHow long do you think it would take to unscramble

these anagrams?

People said it would take about 10 seconds, yet on

average they took about 3 minutes (Goranson, 1978).

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Psychological Science

1. How can we differentiate between uniformed opinions and examined conclusions?

2. The science of psychology helps make these examined conclusions, which leads to our understanding of how people feel, think, and act as they do!

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4 GOALS OF PSYCHOLOGY

1. DESCRIBE

2. EXPLAIN

3. PREDICT

4. INFLUENCE

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The Scientific Attitude

The scientific attitude is composed of curiosity (passion for exploration), skepticism

(doubting and questioning) and humility (ability to accept responsibility when wrong).

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Critical Thinking

Critical thinking does not accept arguments and

conclusions blindly.

It examines assumptions,

discerns hidden values, evaluates

evidence and assesses

conclusions.The Amazing Randi

Courtesy of the Jam

es Randi E

ducation Foundation

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Scientific Method

Psychologists, like all scientists, use the scientific method to construct theories that organize, summarize

and simplify observations.

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Psychologists Analyze Data Scientifically

• Behavior must be measurable– detected by direct observation or

other measuring devices

• Methods and data must be objective

– no opinions or bias

• Scientists must be able to communicate the results of their experiment to others

– Meetings, journals

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Guidelines cont.

• Procedures must be repeatable– Other scientists can do

the same procedure or experiment

• Must use an organized and systematic approach in gathering data

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The Testing Method

•Reliability: a measure of consistency; must yield similar results on different testing occasions

•Validity: the degree to which a test measures what it is suppose to measure

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A Theory is an explanation that integrates principles and organizes

and predicts behavior or events.

For example, low self-esteem contributes to depression.

Theory

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A Hypothesis is a testable prediction, often prompted by a theory, to enable

us to accept, reject or revise the theory.

People with low self-esteem are apt to feel more depressed.

Hypothesis

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Research would require us to administer tests of self-esteem and

depression. Individuals who score low on a self-esteem test and high on a depression test would confirm our

hypothesis.

Research Observations

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Research Process

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Description

Case Study

A technique in which one person is studied in depth to reveal underlying behavioral principles.

Is language uniquely human?

Susan K

uklin/ Photo R

esearchers

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Case Study

A clinical study is a form of case study in which the therapist

investigates the problems associated

with a client.

http://behavioralhealth.typepad.com

Clinical Study

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METHODS cont.• CASE-STUDY METHOD:

– Study an individual’s background forces that influence their behavior (family background, home life, neighborhood, school, etc.)

– ADVANTAGE:• Can exhibit individual differences and suggest

hypotheses• Can study phenomena you cannot manipulate• Can generate hypotheses to be tested

– DISADVANTAGE:• Information comes from family,

teachers and friends of individual being studied (biased?)

• Info. may be misleading• Can’t generalize nor replicate• Observer bias could be present• Cannot show causality• Psychologists can guide patients into saying

what they want hear

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METHODS cont.

• INTERVIEWS:– One-on-one questioning– ADVANTAGE:

• Develop rapport, relaxed atmosphere, questions in advance/flexibility

– DISADVANTAGE:• getting rid of the personal

prejudices of the interviewer, difficulty in expressing the results of an interview in exact terms

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METHODS cont.

• QUESTIONNAIRE:– ADVANTAGES:

• Gather facts about individuals or opinions

• Answers can be treated statistically

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METHODS cont.• TESTS

– I.Q.– Aptitude (A.S.V.A.B.)– Achievement (A.C.T., S.A.T.,

M.A.P.)– ADVANTAGES:

• more objective data than interviews and questionnaires

• Results can be expressed in statistical terms

• Scores can be compared with scores for large groups

– DISADVANTAGES:• Results do not give full and final

answers to individual problems

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Survey

A technique for ascertaining the self-reported attitudes, opinions or behaviors of people usually done by questioning a

representative, random sample of people.

http://ww

w.lynnefeatherstone.org

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Survey• Reveals attitudes and behaviors of large sample of people

•Learn about behavior and mental processes that cannot be observed in the natural setting or studied experimentally

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Limitations

• Limited generalization• Replication sensitive to sample selected

• Give socially desirable answers• Exaggerated answers to foul up results

• Different interviewers for different samples (gender, SES, ethnicity)

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Limitations (cont.)

•Easy to bias by Wording Effect

-“Given the number of shootings in schools, should we regulate handguns? True or False

-Cannot establish causal relationships

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Survey

Wording can change the results of a survey.

Q: Should cigarette ads and pornography be allowed on television? (not allowed vs.

forbid)

Wording Effect

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Survey

A tendency to overestimate the extent to which others share

our beliefs and behaviors.

False Consensus Effect

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Samples and Populations

• Example: Alf Landon defeated Franklin D. Roosevelt in 1936 poll (Roosevelt won by landslide)- surveyed voters by phone-during Great Depression

Wealthy->phones>Republican

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Samples• Must accurately represent the population they are intended to reflect.

• Only representative samples allow us to generalize from research samples to populations.

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Sample/Population• Sample: The individuals who are studied; part of a population

• Population: a complete group of organisms or events

• Infer:Draw a conclusion

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Problems in Generalizing

• Research sample (consider gender, age, ethnicity)

• Volunteer Bias

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Volunteer Bias

A source of bias or error in research that

reflects the prospect that people who offer to participate in research

studies differ systematically from people who don’t.

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Volunteer Bias

• More willing to disclose intimate information

• Volunteers have more spare time than nonvolunteers

• How do they differ from the population at large?

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Problems with Generalization

• Demographic variables:-age-education-socioeconomic status-marital status-number of children-location

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Survey

Random Sampling

If each member of a population has an equal chance of inclusion into a sample, it is called a

random sample (unbiased). If the survey

sample is biased, its results are not valid.

The fastest way to know about the marble color ratio is to blindly transfer a few into a smaller jar and count them.

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QuestionIf scientists conducted research with a “random sample” of students from Valencia, would their sample represent the

general U.S. population? Why or why not?

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Naturalistic ObservationObserving and recording the behavior of animals in the wild and recording self-seating patterns in a multiracial school lunch room constitute naturalistic observation.

Courtesy of G

ilda Morelli

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METHODS

• NATURAL OBSERVATION:

– Observing and recording the behavior of organisms in their natural environment.

– ADVANTAGE:

description of the way organisms behave in their surroundings

– DISADVANTAGE:

no information on how or why the behavior occurs

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METHODS cont.

• DIRECTED OBSERVATION:– Involves observing

behavior under controlled conditions in an experimental or a laboratory setting

– ADVANTAGE:• Allows for control of

events and behaviors

– DISADVANTAGE:• Taking an organism from

its natural environment may change its behavior

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Descriptive Methods

Case studies, surveys, and naturalistic observation describe

behaviors.

Summary

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Assignment

• Form a hypothesis about human behavior and use the method of naturalistic observation to support/refute your hypothesis.

• Write what you observed and concluded.• Ex: If there are sales, then more women

than men will shop at malls. • Due MONDAY SEPTEMEBER 15

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longitudinal studies

• A psychologist studies the same group of people at regular intervals over a period of years to determine whether their behavior and/or feelings have changed and if so, how.

• Ex: Studying you when you were 5, then 10, then 15, then 20, then 25, then 30, etc…

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cross-sectional studies.

• In this study, psychologists organize individuals into groups based on age.

• Then, these groups are randomly sampled, and the members of each group are surveyed, tested, or observed simultaneously.

• Single point in time (snapshot)

• Ex: IQ, memory, disease

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Correlation

When one trait or behavior accompanies another, we say the two correlate.

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = 0.37+

Correlation Coefficient is a statistical measure of the relationship between two

variables.

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Correlational Method

Examines the extent to which two or more variables are related and can

predict one another.

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Correlational Method

• Virtues:-reveals relations of variables outside the lab-replication possible

• Limitations:-cannot establish causal relationships because you do not manipulate the variables

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Correlation Coefficient

•A number that varies between +1.00 and -1.00

•Expresses the strength and direction (+/-) of the relationship between two variables

•The closer it is to 1.00 (regardless of +/-) the stronger the relationship

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Positive Correlation

•A relationship between variables in which one variable increases as the other also increases

• Example: Hours of study and GPA

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Positive Correlation

•A positive relationship means:As (A) increases, so does (B)

Hours of study (A) is positively correlated with GPA (B)

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Negative Correlation

A relationship between two variables in which one

variable increases as the other decreases.

•Example: Hours of TV and GPA

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Negative Correlation

•A negative relationship means:As (A) increases, (B) decreases

Number of hours of TV (A) has a negative relationship with GPA (B)

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Correlation Research

• Correlational research may suggest but does not show cause and effect

• Often seems clear cut:Increase in Hours of study-> increase in

GPA • But could go other way:Students doing well in school are motivated to study more

GPA-> Hours of study

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Correlation Research

•Or some third factor (Confounding Variable): Achievement Motivation could cause both

-> Hours of study-> GPATest: length of marriage is correlated with male baldness.

Does marriage cause baldness?

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Perfect positivecorrelation (+1.00)

Scatterplot is a graph comprised of points that are generated by values of two

variables. The slope of the points depicts the direction, while the amount of scatter depicts the strength of the relationship.

Scatterplots

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No relationship (0.00)Perfect negativecorrelation (-1.00)

The Scatterplot on the left shows a negative correlation, while the one on the right shows no

relationship between the two variables.

Scatterplots

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DataData showing height and temperament in people.

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Scatterplot

The Scatterplot below shows the relationship between height and temperament in people. There

is a moderate positive correlation of +0.63.

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or

Correlation and Causation

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Illusory Correlation

The perception of a relationship where no relationship actually exists. Parents conceive

children after adoption.

Confirming evidence

Disconfirming evidence

Do not

adopt

Disconfirming evidence

Confirming evidence

Adopt

Do not conceiveConceive

Michael N

ewm

an Jr./ Photo Edit

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IMPORTANT

Correlation

does NOT mean Causation!!!

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Given random data, we look for order and meaningful patterns.

Order in Random Events

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

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Order in Random Events

Given large numbers of random outcomes, a few are likely to express order.

Angelo and Maria Gallina won two California lottery games on the same day.

Jerry Telfer/ S

an Francisco C

hronicle

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Experimentation

Like other sciences, experimentation is the backbone of psychology research.

Experiments isolate causes and their effects.

Exploring Cause and Effect

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Experimental Method

A scientific method that seeks to confirm cause and effect relationships

by introducing independent variables and observing their effects on dependent variables.

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Experimental Method

•Treatment: in experiments, a condition received by participants so that its effects may be observed.

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Many factors influence our behavior. Experiments (1) manipulate factors that interest us, while other factors are kept

under (2) control.

Effects generated by manipulated factors isolate cause and effect relationships.

Exploring Cause & Effect

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An Independent Variable is a factor manipulated by the experimenter.

The effect of the independent variable is the focus of the study. For example, when examining the effects of

breast feeding upon intelligence, breast feeding is the independent variable.

Independent Variable

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A Dependent Variable is a factor that may change in response to an

independent variable. In psychology, it is usually a behavior

or a mental process.

For example, in our study on the effect of breast feeding upon intelligence, intelligence is the dependent variable.

Dependent Variable

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Experimental Research

Manipulate the Independent Variable (IV)

Holding all other variables constant

Observe the impact on the Dependent Variable (DV)

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DRY MIX

Dependent Manipulate

Result Independent

Y X

Operational Definition of DV-the parameters of how we measure things

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Experimental Research

Example: Aggression & Alcohol

(IV): Alcohol-administered at different levels, doses

(DV):Aggressive behavior

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Experimental Research• Experimental Participants:Partake of the treatment (example: members would ingest alcohol)

• Control Group: do not take the treatment

(example: do not ingest alcohol)

*** all other conditions are held constant (helps determine cause and effect)

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Placebo

“Sugar pill” often results in the behavior that people expect.

•Physicians now and then give sugar pills to demanding, but healthy people. They often report they feel better.

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PlaceboExample: Tonic water & alcohol•Giving participants placebo (tonic water) but they think they are drinking alcohol

•We can conclude that changes in behavior stem from their beliefs about alcohol, not the alcohol itself.

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Blinds and Double Blinds

Expectations:-Aggression may not have resulted from alcohol because individuals may have expectations of the effects of alcohol.

-People act in stereotypical ways when they believe they have been drinking alcohol.

(people may become less anxious in social situations, more aggressive, or more sexually aroused)

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BlindWell-designed experiments control for the effects

of expectations by creating conditions under which participants are

unaware of the treatment.

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Double-Blind Studies

A study in which neither the participants nor the persons measuring results know who has received the

treatment.

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In evaluating drug therapies, patients and experimenter’s assistants should

remain unaware of which patients had the real treatment and which patients had the

placebo treatment.

Evaluating Therapies

Double-blind Procedure

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Assigning participants to experimental (Breast-fed) and control (formula-fed) conditions by random assignment minimizes pre-existing

differences between the two groups.

* Different from random sampling

Evaluating Therapies

Random Assignment

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ExperimentationA summary of steps during experimentation.

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ComparisonBelow is a comparison of different

research methods.

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Statistical Reasoning

Statistical procedures analyze and interpret data allowing us to see what the unaided eye misses.

Composition of ethnicity in urban locales

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Describing DataA meaningful description of data is

important in research. Misrepresentation may lead to incorrect conclusions.

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Measures of Central Tendency

Mode: The most frequently occurring score in a distribution.

Mean: The arithmetic average of scores in a distribution obtained by adding the scores and then dividing by the number of scores that were added together.

Median: The middle score in a rank-ordered distribution.

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M&Ms Activity

1) Quantify (count) the data within the bag=total M&Ms

2) Sort them according to color (10 orange, 3 red, 4 green, etc…)

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M&M Activity

3) Determine the groups quantity (total)

4) Find the groups mean5) Find individual mode6) Find group’s mode

Bi-modal=> two categories with the same mode

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Measures of Central Tendency

A Skewed Distribution

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Measures of Variation

Range: The difference between the highest and lowest scores in a distribution.

Standard Deviation: A computed measure of how much scores vary around the mean.

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M&M Activity

7) Find the range of group’s bag quantity

*Highest # of m&ms-lowest # of m&ms

8) Find the range of colors in individual bag

9) Calculate Standard Deviation

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Standard Deviation

1) Determine the mean2) Subtract the mean from every number to get

the list of deviations (negative numbers are ok)3) Square the resulting list of numbers4) Add up all the resulting squares to get their

total sum5) Divide your result by one less than the number

of items in the list6) To get the SD, take the square root of the

resulting number

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Practice Standard Deviation

your list of numbers: 1, 3, 4, 6, 9, 19

1) mean: (1+3+4+6+9+19) / 6 = 42 / 6 = 7

2) list of deviations: -6, -4, -3, -1, 2, 12

3) squares of deviations: 36, 16, 9, 1, 4, 144

4) sum of deviations: 36+16+9+1+4+144 = 210

5) divided by one less than the number of items in the list: 210 / 5 = 42

6) square root of this number: square root (42) = about 6.48

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Standard Deviation

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Making Inferences

A statistical statement of how frequently an obtained result occurred by

experimental manipulation or by chance.

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Making Inferences

Representative samples are better than biased samples.

Less variable observations are more reliable than more variable ones.

More cases are better than fewer cases.

When is an Observed Difference Reliable?

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Making Inferences

When sample averages are reliable and the difference between them is relatively large,

we say the difference has statistical significance.

For psychologists this difference is measured through alpha level set at 5 percent (.05)

When is a Difference Significant?

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FAQ

Q1. Can laboratory experiments illuminate everyday life?

Ans: Artificial laboratory conditions are created to study behavior in simplistic terms. The goal is

to find underlying principles that govern behavior.

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FAQ

Q2. Does behavior depend on one’s culture?

Ans: Even when specific attitudes and behaviors vary across cultures, as they often do, the underlying processes are much the same.

Am

i Vitale/ G

etty Images

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FAQ

Q3. Does behavior vary with gender?

Ans: Yes. Biology determines our sex, and culture further bends the genders.

However, in many ways woman and man are similarly human.

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FAQ

Q4. Why do psychologists study animals?

Ans: Studying animals gives us the understanding of many behaviors that may have

common biology across animals and humans.

D. Shapiro, © Wildlife Conservation Society

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FAQ

Q5. Is it ethical to experiment on animals?

Ans: Yes. To gain insights to devastating and fatal diseases. All researchers who deal with animal research are required to follow

ethical guidelines in caring for these animals.

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FAQ

Q6. Is it ethical to experiment on people?

Ans: Yes. Experiments that do not involve any kind of physical or psychological harm beyond normal levels encountered in daily

life may be carried out.

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FAQ

Q7. Is psychology free of value judgments?

Ans: No. Psychology emerges from people who subscribe to a set of values and judgments.

© Roger Shepard

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FAQ

Q8. Is psychology potentially dangerous?

Ans: It can be, but it is not. The purpose of psychology is to help humanity with

problems such as war, hunger, prejudice, crime, family dysfunction, etc.