Lecture 2

Ch. 1Psychological Science

Lecture 2

1. Why do we need to use a scientific approach?2. What does science value?3. The Scientific Method4. Experimental Designs5. Correlation vs. Causation6. In-class Activity 17. Research Ethics

Why do we need to use a scientific approach?

• Are intuition and common sense enough?

What characteristics are valued in scientists?

The Scientific Method

Methods for studying Psychology

• Be able to identify each method• Know the pros and cons for using each

method

Description

Case Study

Susan K

uklin/ Photo R

esearchers

Surveyhttp://w

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Naturalistic Observation

Courtesy of G

ilda Morelli

How well do you understand correlations?

B. I get it!

C. I’m almost there.

D. Sort of.

E. Not really.

F. I have no clue what you’re talking about.

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.

Positive Relationships

High

Low

GP

A

1-3 4-6 7-9Hours studying

Negative Relationships

High

Low

GP

A

Low Mod High

Alcohol Consumption

No relationship

Honesty

High

Low

SES

Low Mod High

Figure 5-5: A Perfect Positive Correlation

r = 1

Figure 5-6: A Perfect Negative Correlation

r = -1

Non-perfect correlation

-5

0

5

10

15

20

25

30

35

40

45

50

Sta

te a

nxie

ty

-.2 -.1 0 .1 .2 .3 .4 .5arcsin ave WM Unpl-neut

Bivariate ScattergramInclusion criteria: remove 917 from 062608setarcsin.svd

The relationship between being in a state of anxiety and performance on a memory task with emotional distracters

r=-0.326

People who smile more intensely as children (as measured by number of crow’s feet around the eyes in photos) are more likely to remain married through middle age.

A. Positive correlation B. Negative correlation C. Zero correlation

People who sleep less than 5 hours a night on average are more likely to have calcium deposits in their arteries.

People who are taller are more likely to have higher incomes. (This is especially true in sales.)

People who multitask the most are the worst at it (memory, ability to switch from one task to another and being able to focus on a task).

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 E

dit

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

factors are kept under (2) control.

Be able to identify the independent and dependent variables in examples of studies.

Exploring Cause & Effect

Students are randomly assigned to take a test in either a hot room or a comfortable room. We’ll then compare test scores to see if hot rooms negatively affect test-taking.

What is the independent variable?

C. Students

D. Room temperature

E. Test scores

F. Tests

G. All of these

What is the dependent variable?

B. Students

C. Hot room

D. Comfortable room

E. Test scores

F. All of these

Describing DataA meaningful description of data is important in

research. Misrepresentation may lead to incorrect conclusions.

Measures of Central Tendency

A Skewed Distribution

Measures of Variation

Range

Standard Deviation

Evaluating the results of a study

• What increases the chance that a difference between groups is a real, reliable effect?

Research Ethics

• Animal research

• Human research

In-class activity 1

• Get into groups of 2-4• Make sure you turn in the handout with all

your names on it