1

Thinking Critically with Psychological

Science

Unit II-Modules 4-8

2

Thinking Critically with Psychological Science

The Need for Psychological Science The limits of Intuition and

Common Sense

The Scientific Attitude

The Scientific Method

3

Thinking Critically …

Description The Case Study

The Survey

Naturalistic Observation

4

Thinking Critically …

Correlation Correlation and Causation Illusory Correlation Perceiving Order in Random

Events

5

Thinking Critically …

Experimentation Exploring Cause and Effect

Evaluating Therapies

Independent and Dependent Variables

6

Thinking Critically …

Statistical Reasoning Describing Data

Making Inferences

FAQs About Psychology

7

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)

8

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.

9

Limits of Intuition

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

meeting with job applicants.

Taxi/ G

etty Images

10

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

11

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).

Perceiving Order in Random Events

• Comes from our need to make sense out of the world–Coin flip

–Poker hand

13

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!

14

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).

15

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

16

Scientific Method

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

theories that organize, summarize and simplify observations.

17

A Theory is an explanation that integrates principles and organizes

and predicts behavior or events.

For example, low self-esteem contributes to depression.

Theory

18

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

The Scientific Method• Theory

– “mere hunch”• Hypothesis

– Can be confirmed or refuted• Operational Definition

• A carefully worded statement of the exact procedures used in a research study

• Replication (repeat)• Repeating the essence of a research study,

usually with different participants to see whether the basic findings extends to others

20

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

21

Research Process

22

Experimentation

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

isolate causes and their effects.

Exploring Cause and Effect

23

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

24

The Hawthorne Effect

• But even the control group may experience changes.

• Just the fact that you know you are in an experiment can cause change

Whether the lights were brighter or dimmer, production went up in the Hawthorne electric plant.

25

An Independent Variable is a factor manipulated by the experimenter. The effect of the independent variable is the focus of the study.

– Ex. If there is a drug in an experiment, the drug is almost always the independent variable.

For example, when examining the effects of breast feeding upon intelligence, breast feeding is the independent variable.

Independent Variable

26

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. •The dependent variable would be the effect of the drug.

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

Dependent Variable

27

Confounding Variables

• AKA extraneous variables• They are other things that can affect the

outcome of the experiment.• If I wanted to prove that smoking (A) causes

heart issues (B), what are some confounding variables?

• A confounding variable is anything that could cause change in B, that is not A.

Ex. Lifestyle (overeating), family history may also effect the heart.

Other confounding variables: placebo effect, holidays, time of day…

28

ExperimentationA summary of steps during experimentation.

29

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

Different ways we observe and describe people….

30

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

31

SurveyA technique for ascertaining the self-reported attitudes, opinions or behaviors of people usually done by questioning a representative, random sample of people. •Most common type of study in psychology

•Measures correlation

•Cheap and fast

•Need a good random sample

32

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

33

Survey

A tendency to overestimate the extent to which others share our beliefs and behaviors.

False Consensus Effect

34

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.

35

Naturalistic Observation•Watch subjects in their natural environment.•Do not manipulate the environment.

Ex. Observing and recording the behavior of animals in the wild

Ex. Recording self-seating patterns in a multiracial school lunch room constitute naturalistic observation.

Courtesy of G

ilda Morelli

36

Descriptive Methods

•Case studies, surveys, and naturalistic observation describe behaviors.

Summary

37

Research Method: CorrelationExpresses a relationship between 2 variables.

When one trait or behavior accompanies another, we say the two correlate.ex. Smoking and lung cancerCorrelation does not necessarily

mean causationCorrelations helps to predict

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.

38

Correlation Coefficient

• A number that measures the strength of a relationship.

• Range is from -1 to +1

• The relationship gets weaker the closer you get to zero.

Which is a stronger correlation?

• -.13 or +.38• -.72 or +.59• -.91 or +.04• *** NOTE*** • You will NOT have to

know how to calculate the correlational coefficient! Get this in your Stats class!

39

Types of Correlation

Positive Correlation• The variables go in

the SAME direction.

Negative Correlation• The variables go in

opposite directions.

Studying and grades hopefully has a positive correlation. Drug use

and grades probably has a negative correlation.

40

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

41

No relationship (0.00)-No correlationPerfect 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

42

DataData showing height and temperament in people.

43

Scatterplot

The Scatterplot below shows the relationship between height and temperament in people. There is a moderate positive correlation of +0.63.

44

or

Correlation and Causation

Correlation

Illusory Correlations

• Illusory Correlation–Perceived non-existent correlation

–A random coincidence

46

Experimenter Bias

• Another confounding variable

• Not a conscious act• Double-blind procedure

– Neither the participants nor the research assistants collecting the data will know which group is receiving the treatment.

47

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

48

Assigning participants to experimental (Breast-fed) and control (formula-fed) conditions by random assignment minimizes pre-existing differences between the two groups.

Evaluating Therapies

Random Assignment

49

ComparisonBelow is a comparison of different research methods.

50

Statistical Reasoning

Statistics are tools that help us see and interpret what the unaided eye might miss.

51

Describing DataA meaningful description of data is important in research. They are numbers that describe the main characteristics of the data.Misrepresentation may lead to incorrect conclusions.

52

Measures of Central Tendency

A single score that represents a whole set of numbers.

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.

Watch out for extreme scores and outliers!

53

Measures of Central Tendency

A Skewed Distribution

54

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.

55

Standard Deviation

56

Standard Deviation

•Less variability of scores is better than greater variability

•Therefore, if a group of scores has a smaller standard deviation, then you can draw more stable conclusions from the data set.

57

Normal Curve

Most cases fall near the mean and fewer cases fall near either extreme.

Roughly 68% of scores fall within one SD on either side of the mean

About 95% of scores fall within two SD

Descriptive Statistics

Measures of Variability

• Normal Curve

Inferential Statistics

When Is an Observed Difference Reliable?

• Inferential statistics• Representative samples are better

than biased samples• Less-variable observations are

more reliable than those that are more variable

• More cases are better than fewer

Inferential Statistics

When Is a Difference Significant?• Statistical significance

–The averages are reliable

–The differences between averages is relatively large

–Does imply the importance of the results

Psychology Applied• Can laboratory experiments illuminate

everyday life?– The principles, not the research findings, help

explain behavior

• Does behavior depend on one’s culture and gender?–Culture–Gender

62

APA Ethical Guidelines for Research

• IRB- Internal Review Board– A committee at each

institution where research is conducted to review every experiment for ethics and methodology

– Reviews and approves all research

• Both for humans and animals.

63

Animal Research

• Clear purpose

• Treated in a humane way

• Acquire animals legally

• Least amount of suffering possible.

64

Human Research

• No Coercion- must be voluntary• Informed consent

– Participants are told enough to enable them to choose whether they wish to participate

• Anonymity– Keep information about participants confidential

• No significant risk– Protect from harm and discomfort

• Must debrief– Explain the research afterward; including its purpose and

any deceptions