Thinking Critically Thinking Critically With With

Psychological SciencePsychological Science

Chapter 1

AP Psychology ~ Ms. Justice

The Monty Hall Problem: Common Sense or Statistics?

BIG IDEASBIG IDEASThe Need for Psychological Science1: Why are the answers that flow from the scientific approach more

reliable than those based on intuition and common sense?2: What are 3 main components of the scientific attitude?2: What are 3 main components of the scientific attitude?

How Do Psychologists Ask and Answer Questions?3: How do theories advance psychological science?4: How do psychologists observe and describe behavior?5: What are positive and negative correlations, and why do they enable

prediction but not cause-effect explanation?6: What are illusory correlations?7: How do experiments, powered by random assignment, clarify cause

and effect?

BIG IDEASBIG IDEASStatistical Reasoning in Everyday Life8: How can we describe data with measures of central tendency and

variation?9: What principles can guide our making generalizations from samples and

deciding whether differences are significant?9: What principles can guide our making generalizations from samples and

deciding whether differences are significant?

Frequently Asked Questions About Psychology10: Can laboratory experiments illuminate everyday life?11: Does behavior depend on one’s culture and gender?12: Why do psychologists study animals, and is it ethical to experiment on

animals?13: Is it ethical to experiment on people?14: Is psychology free of value judgments?

1: Why are the answers that flow from the scientific approach

more reliable than those based on intuition and 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.

§Because of hindsight bias§Because of hindsight biasand judgmentaloverconfidence, we cannot rely solely on intuition and common sense.

Hindsight Bias:Hindsight Bias:

the “I-knew-it-all-along” phenomenon.

§After learning the outcome of an event, many people believe they could have predicted that very outcome. event, many people believe they could have predicted that very outcome. §Common sense more easily describes what has happened than what willhappen. §We only knew the subprime housing market would crash after it actually did crash.

OverconfidenceOverconfidence:Sometimes we think we know more

than we actually know.

Anagrams

WATERWREAT.

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).

.

.

.

.

.

2: What are 3 main components of the scientific attitude?

The scientific attitude is composed of:

§curiosity (passion for exploration)

§skepticism (doubting and questioning)

and and

§humility (ability to accept responsibility when wrong)

§James Randi exemplifies skepticism – he has tested and debunked a variety of psychic phenomena

§The scientific attitude prepares us for critical thinking, which does not accept arguments and conclusions blindly...

Courtesy of the Jam

es Randi E

ducation Foundation

does not accept arguments and conclusions blindly...

§It examines assumptions, discerns hidden values, evaluates evidence and assesses conclusions.

The Amazing Randi

www.randi.org

Courtesy of the Jam

es Randi E

ducation Foundation

James Randi Exposes Uri Geller & Peter Popoff

3: How do theories advance psychological science?

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

organize, summarize and simplify observations.

A theory is an explanation that integrates principles and organizes and predicts behavior or events.

For example, low self-esteem contributes to depression.

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.

§Research would require us to administer tests of self-esteem and depression. §As a check on their biases, psychologists use precise operational definitions of

Research ObservationsResearch Observations

use precise operational definitions of procedures and concepts.§This allows for replication with different participants & materials, which boosts the validity of a study.

Research ProcessResearch Process

Figure 1.1, p. 22

4: How do psychologists observe and describe behavior?

Description is the starting point of any science

Among the oldest research methods is the case study:a technique in which one person (or a chimp?) is studied in depth to reveal underlying behavioral

principles.principles.

Is language uniquely human?

Susan Kuklin/ Photo R

esearchers

The survey, which looks at many cases in less depth, is

a technique for ascertaining the self-reported attitudes, opinions or behaviors of people

usually done by questioning a representative, random sample of people.

http://www.lynnefeatherstone.org

Survey: Wording EffectsSurvey: Wording EffectsWording can change the results of a survey.

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

§ People are much more likely to approve “not allowing” such things than “forbidding” or “censoring” them.§ “aid to the needy” vs. “welfare”§ “affirmative action” vs “preferential treatment”§ “revenue enhancers” vs. “taxes”

Survey: Random SamplingSurvey: Random Sampling

If each member of a population has an equal

chance of inclusion into a sample, it is called a

random samplerandom 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.

Naturalistic ObservationNaturalistic ObservationObserving and recording the behavior of animals in the wild, or recording self-seating patterns in a multiracial

school lunch room are examples of naturalistic observation.

Cou

rtesy of Gild

a Morelli

Before we move on….

Remember that these descriptive methods do not explain behavior.

5: What are positive and negative correlations, and why do they enable prediction but not cause-effect explanation?

CorrelationCorrelationWhen one trait or behavior accompanies

another, we say the two correlate.

Indicates strengthof relationship(0.00 to 1.00)

Correlation coefficient

Indicates directionof relationship

(positive or negative)

r = 0.37+

Correlation coefficient is a statistical measure of the relationship

between two variables.

A scatterplot is a graph comprised of points that are generated by values of two variables. The slope of the

points depicts the direction,

ScatterplotsScatterplots

points depicts the direction, while the amount of scatter depicts the strength of the

relationship.

ScatterplotsScatterplots

No relationship (0.00)

A weak correlation, indicating little

relationship, has a coefficient near zero.

Perfect negativecorrelation (-1.00)

If 2 sets of scores relate inversely (one set going

up as the other goes down), the correlation is

negative. (Example: toothbrushing & decay)

Perfect positivecorrelation (+1.00)

If 2 sets of scores tend to rise or fall together, the correlation is positive.

(Example: height & weight)

Note: Perfect correlations rarely Note: Perfect correlations rarely

occur in the “real world”occur in the “real world”

DataDataData showing height and temperament in people:

Is there a positive correlation, negative correlation, or little-to-no correlation?

Tabl

e 1.

2, p

. 26

ScatterplotScatterplotThe Scatterplot below shows the relationship between

height and temperament in people.

Tabl

e 1.

3, p

. 27

Correlation and CausationCorrelation and CausationCorrelation does not mean causation!

or

Tabl

e 1.

4, p

. 27

6: What are illusory correlations?

Illusory Correlation:Illusory Correlation:A perceived, but nonexistent, correlation.

Illusory correlations can help explain many superstitious beliefs, such as the presumption that infertile couple who

adopt become more likely to conceive.

Do not

Confirming evidence

Disconfirming evidence

Do notadopt

Disconfirming evidence

Confirming evidence

Adopt

Do not conceiveConceive

Michael N

ewman Jr./ Photo E

dit

Figure 1.5, p. 29

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

Order in Random EventsOrder in Random Events

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

Order in Random EventsOrder in Random Events

“With a large enough sample, any outrageous thing is likely to

happen.” ~Diaconis and Mosteller

An event that happens to but

Jerry Telfer/ S

an Francisco Chron

icle

An event that happens to but one in 1 billion people every day

occurs about 6 times a day –2000 times a year.

Angelo and Maria Gallina won two California lottery

games on the same day.

Jerry Telfer/ S

an Francisco Chron

icle

7: How do experiments, powered by random assignment, clarify cause and effect?

ExperimentationExperimentation:

Like other sciences, experimentation is the backbone of psychological research. Experiments isolate causes and their effects.

Exploring Cause and Effect

causes and their effects.

Exploring Cause & EffectExploring Cause & EffectMany factors influence our behavior.

Experiments (1) manipulate factors of interest, while other factors are kept under (2) control.

Effects generated by manipulated factors isolate cause and Effects generated by manipulated factors isolate cause and effect relationships.

For example: the effects of bottle feeding vs. breast-feeding on intelligence

vs.

Evaluating TherapiesEvaluating Therapies

In evaluating drug therapies, patients and

experimenter’s assistants should remain unaware of

Double-blind Procedure

experimenter’s assistants should remain unaware of which patients had the real

treatment and which patients had the placebo

treatment.

Evaluating TherapiesEvaluating Therapies

Assigning participants to experimental (breast-fed) and control (formula-fed)

conditions by random

Random Assignment

conditions by random assignment minimizes pre-existing differences

between the two groups.

NOT random assignment!NOT random assignment!

Independent VariableIndependent VariableAn 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 intelligence, breast feeding is the independent variable.

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

• Look for the DV first when identifying variables in a study. Ask yourself, “What is the researcher measuring or looking for in this study?”

• Look for the IV second when identifying variables in a study. Ask yourself, “What do the researchers hope will cause the DV in this study?”

Find the IV & the DVHypothesis from a 2002 study: "There will be a statistically significant difference in graduation rates of at-risk high-school seniors who participate in an intensive study program as opposed to at-risk high-school seniors who do not participate in the intensive study program."

ExperimentationExperimentationA summary of steps during experimentation (effects of bottle feeding vs. breast-feeding on intelligence.)

ComparisonComparisonBelow is a comparison of different research

methods.

Table 1.3, p. 33

8: How can we describe data with measures of central tendency and variation?

Statistical ReasoningStatistical Reasoning

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

Composition of ethnicity in urban locales

Statistical Reasoning in Everyday LifeStatistical Reasoning in Everyday Life

Doubt big, round, undocumented numbers as they can be misleading and before long,

become public misinformation.

Apply simple statistical reasoning in everyday life to think smarter!

Describing DataDescribing Data

A meaningful description of data is important in research. Misrepresentation may lead to incorrect conclusions.

Measures of Central TendencyMeasures 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 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.

Measures of Central TendencyMeasures of Central TendencyA Skewed Distribution

Measures of VariationMeasures of VariationRange: The difference between the highest and lowest scores in a distribution.

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

Standard DeviationStandard Deviation

Table 1.4, p. 36

Normal CurveNormal CurveA symmetrical, bell-shaped curve that describes the

distribution of many types of data (normal distribution). Most scores fall near the mean.

9: What principles can guide our making generalizations from

samples and deciding whether differences are significant?

In deciding when it is safe to generalize from a sample, keep 3 principles in mind:

§ Representative samples are better than biased samples.§ Less-variable observations are more reliable than more

When is an Observed Difference Reliable?When is an Observed Difference Reliable?

§ Less-variable observations are more reliable than more variable ones.

§ More cases are better than fewer cases.

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

the difference has statistical significance. It is probably not due to chance variation.

When is a Difference Significant?When is a Difference Significant?

For psychologists this difference is measured through alpha level set at

5 percent.

Frequently Asked Questions About Frequently Asked Questions About PsychologyPsychology

10. Can laboratory experiments illuminate everyday life?

Answer: Artificial laboratory conditions are created to study behavior in simplistic terms. The created to study behavior in simplistic terms. The goal is to find underlying principles that govern behavior. Those principles, not the specific findings, help explain everyday behaviors.

11. Does behavior depend on one’s culture and gender?

Answer: Even when specific attitudes and behaviors vary across cultures, as they often do, the underlying processes

are much the same. Biology determines our sex, and culture further bends the genders. However, in many ways woman

and man are similarly human.and man are similarly human.

Ami V

itale/ G

etty Images

Our shared biological

heritage unites us.

12. Why do psychologists study animals, and is it ethical to experiment on animals?

§Studying animals gives us the understanding of many behaviors that may have common biology across animals and humans.

From animal studies, we have gained insights to devastating §From animal studies, we have gained insights to devastating and fatal diseases.

§All researchers who deal with animal research are required to follow ethical guidelines in caring for these animals.

D. Shapiro, © Wildlife Conservation Society

13. Is it ethical to experiment on people?

Answer: Yes. Experiments that do not involve any kind of physical or psychological harm beyond normal levels encountered in daily life may be carried out.

Ethical principles urge researchers to:1. Obtain informed consent1. Obtain informed consent2. Protect from harm and discomfort3. Maintain confidentiality4. Explain research afterward

Ethics in Psychological Research: The Stanford Prison Experiment

14. Is psychology free of value judgments?

Answer: No. Psychology emerges from people who subscribe to a set of values and judgments that determine what will be studied, how it will be

studied, and how the results will be interpreted.

© Roger Shepard