Chapter 1:

Thinking Critically With Psychological Science

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The Scientific Method

• Psychology - the science of behavior and mental processes

• What makes a discipline a science?

• Methods used to study its content

• Science - based on scientific method

• Relies on empirical data

• Information that can be systematically…

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• observed, measured, and recorded • as you attempt to• study behavior and mental processes

• Scientific attitude- Curious skepticism/critical thinking- “It ain’t so much the things we don’t know that get

us into trouble. It’s the things we know that just ain’t so.” (Ward)

- Humility.

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• Scientific attitude vs. intuition/common sense• What’s wrong with i/cs.?• Sometimes wrong (page 20)• Why?

1) Hindsight bias/I-knew-it-all-along phenomenon2) Overconfidence – wreat = water 3) Ochsa4) Selective attention 5) Critical inquiry has led to surprises – (p.24) 6) Point to Rem. (p. 22)

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The Scientific Method• Systematically observe, measure, and record when

studying behavior and mental processes• As psychologists do this, they have three goals.

• To accurately:

(1) describe,

(2) predict and

(3) explain behavior (answer the question why).

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Accurate Description A. The Case Study

B. Naturalistic Observation

C. The Survey - representative sample, random sample.

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Predicting Behavior

• Correlational approach -

• understanding the relationship between two variables

• If one variable goes up, what happens to the other variable?

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• (:) (:)(:) (:?)

• Examples.

• Findings - reported using a correlational coefficient• A number from +1 to –1• Pt. to remember – (p. 33)• Correlation does not prove causation • Related variables - does not mean that one variable

causes the other • Examples.

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Explaining Behavior • Experimentation - the experiment

• Experiment -

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a highly controlled situationin which the experimenter 1) manipulates a variable, 2) observes a variableand 3) controls for extraneous variables

• Example.

Altruistic Behavior Experiment

• Psychologist notices something

• Has hunch - develops into hypothesis

• An if-then statement of prediction

• A statement to be tested using systematic observation.

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• Hypothesis in this study:

• If many people observe an emergency, then the less likely or more slowly individuals will be to help

• Subjects - college students recruited from ad in college newspaper.

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• Subjects randomly assigned to one of three groups - (2 person, 3 person, 6 person)

• Random assignment - assures that every subject has an equal chance of being in any of the three groups

• Experimenter manipulates a variable. What variable is the experimenter going to manipulate in this study?

• Size of the group - 2,3,6 person.

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STape

Tape

Tape

Tape

Tape

The variable which is manipulated is called the __________________.independent variable

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• After manipulating a variable, the experimenter then _________________observes a variable

• What variable is going to be observed?

helping behavior - how many subjects went for help and how long it took to do so

• Findings:

• Observed variable is called dependent variable

– 2 person group 85% 52 seconds– 3 person group 62% 93 seconds– 6 person group 31% 166 seconds

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• Experimenter manipulated a variable and observed a variable

• What else must be done?• Control for extraneous variables • What is an extraneous variable?• A variable which can influence the dependent variable

if not controlled for. Examples:– nursing students; introversion/extroversion; other

• How do we control for extraneous variables?• Random assignment of subjects to groups.

• Was the hypothesis supported?- 2 person group 85% 52 seconds - 3 person group 62% 93 seconds - 6 person group 31% 166 seconds

• Would we generalize and say the hypothesis is a fact which would relate to many situations?

• No. This is just one study. We need many other studies (replication) testing this hypothesis. The word fact is rarely used.

• What is a fact? Example.1616

• Conduct further research testing the hypothesis

• How much support for the hypothesis

• If much support - greater confidence in the hypothesis

• Hypothesis regarding helping behavior has much support

• Called bystander effect.

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Other Examples of Experiments:• If people drink alcohol, then their thinking

ability will be impaired

• Randomly assign subjects to two groups

• One group gets strong tasting drink mixed with alcohol

• Other group gets drink that contains no alcohol, but tastes the same

• What variable has been manipulated?18

• What variable will be observed?

• Thinking ability, by giving a test of thinking

• How would experimenter control for extraneous variables?

• By random assignment

• Difference between groups likely to be due to the manipulation of the independent variable.

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• Placebo used • Placebo - an inert substance that was

administered instead of alcohol• Group which got the placebo = control

condition• Involved a double blind procedure• Neither subjects nor researchers knew who

was getting the alcohol and who was not.

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Another Example: Can subliminal tapes improve self-esteem and memory?

• Random assignment of subjects to one of four groups

• Subjects given self-esteem and memory tests

• Group A - memory enhancement subliminal tape

• Group B - self-esteem subliminal tape.

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• Group C - self-esteem subliminal tape, but told they listened to memory enhancement subliminal tape

• Group D - memory enhancement subliminal tape, but told they listened to self-esteem subliminal tape.

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• Researcher then observed dependent variable

• Dependent variable - measured by giving self-esteem and memory tests again

• Were the tapes effective?

• Had no effects.

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• Yet, those who thought they had heard a memory tape believed their memories had improved

• And those who thought they had heard a self-esteem tape thought their self-esteem had improved

• The tapes had no effect on memory or self-esteem, yet the subjects perceived themselves receiving the benefits they expected.

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• Greatest advantage of the experiment?

• Because the experimenter has manipulated, controlled, and systematically observed, can more make statements about cause and effect

• That is, what has caused behavior.

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Frequently asked questions about psychology:• Can laboratory experiments help us

understand everyday life and behavior?

• It is the resulting principles - not the specific findings that help explain everyday behavior

• As psychologists, we are concerned more with the general principles that explain behavior rather than specific behaviors.

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1. Does behavior depend on one’s culture?

2. Does behavior vary with gender?

3. Why do psychologists study animals?

4. Is it ethical to experiment on animals?

5. Is it ethical to experiment on people?

6. Is psychology free of value judgements?

7. Is psychology potentially dangerous?

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