thinking and hypothesis testing (chapter 6). 2 psychology is a science i.what makes psychology a...

Thinking and Hypothesis Testing (Chapter 6)

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Psychology is a Science

I. What Makes Psychology a Science?

II. What Research Methods Do Psychologists Use?

III. What Ethical Principles Guide Psychological Research?

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I. What Makes Psychology a Science?

1. Empiricism• Acquiring information through careful

observation• Not through logic or intuition

2. Theory Development• A psychological theory is a collection of

interrelated ideas and observations• Taken together, these describe, explain,

and predict behavior and mental processes

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I. What Makes Psychology a Science?Three scientific principles1. Objectivity

• Evaluating research and theory on their own merits

• Not being biased or using preconceived notions

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2. Systematic Observation

– Having a plan for gathering data– Without a systematic plan, a person is

doing casual observation rather than being scientific

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3. Replicability

Confirming findings through repeated observations

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Scientific Method in Psychology

“Does the timing of study sessions influence learning and memory?”

Specific and clearly

defined!

1. State the Problem/Research Question

• A specific and clearly defined question

“How do people learn?”Too vague!

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B. Scientific Method in Psychology

2. Literature Review3. Develop a Hypothesis– An educated guess

– A set of beliefs usually concerning the relationships between variables (a quantifiable characteristic that can take on more than one value-ht, wt, age, gender)

– Often emerges from a theory (Set of general principles that can be used to explain & predict behavior)

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Inductive Methods

A method of formulating hypotheses in which events are observed and then a hypothesis is devised about the events observed

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Deductive Methods

A method of hypothesis testing in which a hypothesis is formulated that is believed to be true and then consequences are inferred from it

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Deductive Reasoning

• Goal: To determine which conclusions are valid given premises or statements that we believe are true

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B. Scientific Method in Psychology

4. Design a Study

– Identify variables and responses to examine

– Decide to how define and measure the variables of interest

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B. Scientific Method in Psychology

5. Collect and Analyze Data

– Must avoid bias in data collection

– Must organize and analyze data, usually using statistics

6. Draw Conclusions and Report Results

7. Publication

8. Replication and Application

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II. What Research Methods Do Psychologists Use?

The Experimental Method

– Systematically manipulating variables and observing the elements of a situation

• Can establish a cause and effect relationship

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The Experimental Method

Two types of variables

1. Independent Variable (IV)

• Intentionally manipulated by the experimenter

2. Dependent Variable (DV)

• Effects of the IV

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Example:

Some children played violent video games, whereas other children played non-violent video games. Then researchers then observed the children playing and measured how many aggressive behaviors the children engaged in.

• What is the independent variable?• What is the dependent variable?

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Terms

Operational Definition

• How will the variable be measured and or recognized?

– Learning = exam score

– Aggression = hitting a person or throwing an object at a person

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Terms

• Reliability: When retested. Do the participant get the same scores?

• Validity: Does the test measure what it is supposed to measure?

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Terms

• Population: A complete group. A group from which a sample is selected.

• Sample: Part (subset) of the population. Who will be in the study.

• Random Sampling: Selection in such a way that every participant has an equal chance of being selected to participate.

• Representative Samples: a sample that is similar to the population in important characteristics (males, females,SES age)

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Biases Samples

• Are not representative of the population from which it was drawn.

• Confounding Variables: confounds confuse the interpretation of results because the influence is not easily separated from the influence of the IV

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Unbiased Samples

• Generalization: To apply observations of a sample to a population

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Procedures

– Participants in the study must be alike on all variables except the IV

– Participants are randomly assigned to groups

• Experimental group receives the treatment

• Control Group does not receive the treatment

• Placebo: an inactive treatment that gives the appearance of being genuine

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Self-fulfilling Prophecies

• The tendency to act in ways that will influence the results of the experiment so that are consistent with expectations

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Double-Blind Procedures

• Neither the experimenter nor the participants (subjects) know the treatment group in which the participant has been assigned

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Example:

Some children played violent video games, whereas other children played non-violent video games. Then researchers observed the children playing and measured the number of aggressive behaviors in which the children engaged.

• What is the Experimental Group?• What is the Control group?

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The Experimental Method

• If the groups are comparable, you can conclude that the manipulation caused an experiment’s effects • Manipulating content of video games

played caused differences in aggressive behavior

• If the groups are not comparable, extraneous variables may “confound the results”

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Experimental Group(IV)

Control Group

Measure effects(DV)

Participants

A. The Experimental Method

Random Assignment

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The Experimental Method

• Can establish cause-and-effect relationships

• However, not all variables can be manipulated

• Quantitative Research: Standard research where statistics and participants are used.

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II. What Research Methods Do Psychologists Use?

B. Descriptive Methods: Qualitative Research•Describe relationships and events•Do not manipulate variables•Therefore, can NOT make

inferences about cause and effect•Five types:

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1. Case Studies

– Intensive study of one case

– Provides extensive data

– May not be generalizable to others

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2. Naturalistic Observation

– Observation of behavior in a naturally occurring situation

– Does not interfere with the natural situation

– Jane Goodall- chimpanzees

– Dianne Fossey- gorillas

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3. Surveys/Interviews/Questionnaires

– Allow researchers to gather large amounts of data from large groups of people

– Sample must be representative

– Relies on participants to be honest and accurate

– Alfred Kinsey

(1948) Sexual Behavior in the Human Male

(1953) Sexual Behavior in the Human Female

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4. Correlational Studies

– Establish relationships between two variables

– Because the variables are not controlled, can NOT infer causation

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4. Correlational Studies

Ice Cream Consumption

Drownings

• Ice cream consumption and drowning are correlated. As ice cream consumption increases, so does the number of drownings.

• But does one cause the other?

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4. Correlational Studies

Ice Cream Consumption

Drownings

• Maybe ice cream consumption could cause drowning (not waiting an hour before swimming???)

• Maybe drowning could cause ice cream consumption (eating ice cream out of grief???)

• Or maybe some third variable explains both…

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4. Correlational Studies

Ice Cream Consumption

Drownings

Hot weather

One can not infer causation from correlation.

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5. Ex Post Facto Studies

– Describe differences between groups of participants

– Groups differ naturally on a variable such as race or gender• Subject variable• Individual differences variable

– Variable is NOT manipulated, so these are not experiments

– Therefore, can not infer causation

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What kind of study?

To understand children’s play behavior, researchers visit a playground and watch children playing.

– Is anything manipulated?

– So, is this experimental or descriptive?

– What kind?

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What kind of study?

To understand memory, researchers study a woman who can remember over 1,000 digits of pi (3.1415…).

– Is anything manipulated?

– So, is this experimental or descriptive?

– What kind?

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What kind of study?

To understand the relationship between class attendance and grades, researchers measure students’ attendance and GPA, and find that students who miss fewer classes have higher GPAs.

– Is anything manipulated?– So, is this experimental or descriptive?– What kind?– Can you conclude better attendance

causes better grades?

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What kind of study?

To understand the relationship between class attendance and grades, researchers have some students miss 0 classes and some miss 5 classes. They find that students who miss fewer classes have higher GPAs.

– Is anything manipulated?– So, is this experimental or descriptive?– Can you conclude better attendance causes

better grades?

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What kind of study?

To understand gender differences in communication, researchers study the communication styles of groups of men and women.

– Is anything manipulated?– So, is this experimental or descriptive?– What kind?

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III. How do psychologists evaluate their research findings?

Using statistics

– Statistics is a branch of mathematics that deals with classifying and analyzing data

– Psychologists use two types:

• Descriptive statistics

• Inferential statistics

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Using Statistics

Descriptive Statistics: Summarize, condense and describe data

Measures of central tendency (mean, median, & mode)

• Mean Average

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Mean

19212223242424252527

(19+21+22+23+24+24+24+25+25+27)/10

Quiz Scores

Mean = 23.4

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Median

ii. Median Middle Score

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Median

19212223242424252527

(19+21+22+23+24+24+24+25+25+27)/10

Mean = 23.4

Quiz Scores

19 21 22 23 24 24 24 25 25 27 19 21 22 23 24 24 24 25 25 27

Median = 24

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Mode

iii. Mode Most common score

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Mode

19212223242424252527

(19+21+22+23+24+24+24+25+25+27)/10

Mean = 23.4

Quiz Scores

19 21 22 23 24 24 24 25 25 27

19 21 22 23 24 24 24 25 25 27

19 21 22 23 24 24 24 25 25 27

Median = 24

19 21 22 23 24 24 24 25 25 27

Mode = 24

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Measures of Variability

Measures of Variability (range, standard deviation)

i. Range • Highest minus lowest score

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Range

19212223242424252527

Quiz Scores

19 21 22 23 24 24 24 25 25 27 19 21 22 23 24 24 24 25 25 27

Range = 27-19 = 8

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ii. Standard Deviation (SD)

• How much do the scores vary, on average, from the mean?

(x - x)2

N

Standard Deviation

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Using Statistics

1.Descriptive Statistics• a. Measures of Central Tendency

• i. Mean• ii. Median• iii. Mode

• b. Measures of Variability• Range• Standard Deviation (SD)

• c. Correlation Coefficients

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c. CorrelationsDescribe relationship between two variables

Strong, Positive RelationshipNumber

of Calories Taken In

5,000

100

Amount of Body Fat5% 30%

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c. Correlations

Strong, Negative Relationship

Amount of Exercise

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0.5

Amount of Body Fat5% 30%

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c. Correlations

No RelationshipSAT Scores

800

200

Amount of Body Fat5% 30%

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c. Correlation Coefficients

Numerical way to describe the relationship between two variables

r Ranges from -1 to +1

• If +• As one variable increases, the other

increases• As one variable decreases, the other

decreases

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Positive Correlations

Number of Calories

Amount of Body Fat

Hours Studying

GPA

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c. Correlation Coefficient

If -•As one variable increases, the other decreases

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Negative Correlations

Amount of Exercise

Amount of Body FatClasses Missed

GPA

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c. Correlation Coefficient

Ranges from -1 to +1

• Closer to |1| (-1 or +1), the stronger the relationship

• Closer to 0, the weaker the relationship

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c. CorrelationsStrong Relationship

r = +1.0

Weaker Relationshipr = +.50

Number of Calories

Amount of Body Fat

Hours Studying

GPA

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c. Correlations

Strong Relationship

r = -1.0

Weaker Relationship

r = -.25

Amount of Exercise

Amount of Body Fat

Classes Missed

GPA

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c. Correlations

No Relationship

SAT Scores

800

200

Amount of Body Fat5% 30%

r = .04

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c. Correlation Coefficients

r = +1.0 Strong, positive correlation

r = -.95 Strong, negative correlation

r = -.33 Moderate, negative correlation

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Inferential Statistics

– Used to determine if research results are significant

– Significant differences are statistically unlikely to occur because of chance alone

– What is the probability of getting a difference between groups this big or bigger due to chance?

– Usually, if p < .05, researcher concludes the results are significant

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III. Ethical Principles

• Were the Milgram’s studies ethical?

• American Psychological Association Guidelines (APA):

• Approval from ethics review committee.

• Conducted in an ethical manner.

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III. Ethical Principles

Ethics are the rules concerning proper conduct that guide research

Human participants:• Must give informed consent• Participation is voluntary• Cannot be coerced into doing anything

physically/psychological harmful.• Without Force• Can decline to participate at any time

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III. Ethical Principles

• Information gained is strictly confidential• Deception: Participants should be

debriefed at the end of the study, explaining the nature & purpose of the study.

• Cases of pain or injury must be explained in advance.

• Minors, Mentally ill or Mentally Retarded can NOT give informed consent.

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Should Humans Be Used In Research?

What do you think?

No• Animals are subjected to painful treatments under the

assumption they are “lesser” than humans• Information may not be generalizable to humans

Yes• Research with animals has allowed for important

studies that would be impossible with humans• The information from such studies is directly relevant

to improving people’s lives

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Animal Ethics

The 3 R’s:1.Live animals should be replaced by

tissue, bacteria, etc.2.Animal suffering should be reduced by

using fewer animals. Harmed when no other alternative.

3.Research procedures should be refined to shorten the experiment.