Chapter 4: Studying Behavior

1
Chapter 4Studying Behavior
2
Remember this stuff?

• Remember that the practice (activity) of
  obtaining information based on experimentation
  and observation is a hallmark of Science
• Also remember that the science of psychology
  strives to describe, predict, control (find
  causes), and explain relationships regarding what
  we do
• To do this, we need to understand what VARIABLES
  are

3
Variables

• A variable is any event, situation, or behavior
  that varies (can be changed in value).
• Four general classifications
• Situational variables describe characteristics of
  the environment.
• Response variables are the responses or behaviors
  of individuals.

4
Variables (cont)

• Participant (subject) variables are individual
  differences.
• Mediating variables are psychological processes
  that mediate the effects of a situational
  variable on a particular response.

5
Which of the following is NOT a variable?
(Imagine game show music playing now)

• Hair color
• Inches in a foot
• A persons Weight
• Attitudes on gun control
• Intelligence scores

6
Examples of Variables

• Variable Name Levels (values)
• Gender Male or Female
• Test Scores correct
• Room Temp. Hot, Warm, Cold
• Room Temp. Degrees Farenheit

7
Operational Definitions of Variables

• A variable must be defined in terms of the
  specific method used to measure or manipulate it
  (this is called the operational definition).

8
Values of a variable

• Nominal Variables
• Different groups with no numeric properties
• Male-female distraction-no distraction
  Catholic-Protestant freshman-sophomore
• Quantitative variables
• Amounts or quantities (7 of something vs. 12 of
  something, etc.
• Numerical (inches, pounds, minutes, etc.)

9
Relationships Between Variables

• Relationships between two variables
• Do the levels of the two variables vary
• systematically together?
• Example
• As the number of days absent increases, do grades
  in the class decrease also?

10
Relationships Between Quantitative Variables

• Positive Increases in the values of one variable
  are associated with increases in the second
  variable. Ex.) Increasing study time is
  associated with higher grades
• Negative Increases in the values of one variable
  are associated with DECREASES in the second
  variable. Ex.) Increasing hours of work are
  associated with lower grades
• Curvilinear
• No Relationship

11
Relationships Between Quantitative Variables

• Curvilinear Increases in the values of one
  variable are associated with both increases and
  decreases of the second variable. Ex.) Anxiety
  can help increase performance until it gets to
  high then it decreases performance
• No Relationship variables do not change in any
  regular way with each other. Ex.) hair color and
  IQ

12
Relationships Between Variables (cont)

• For the purposes of describing relationships,
  variables that have true numeric (QUANTITATIVE)
  properties are called
• Interval scale of measurement (can have negative
  and positive values OR no real zero value)
  Temperature IQ scores
• Ratio scale of measurement (can only be positive
  values) number of hallucinations number of cans
  of beer

13
Relationships Between Variables

• Positive linear relationship (covary in the
• same direction).

14
Relationships Between Variables (cont)

• Negative linear relationship (covary in
  opposite
• directions)

15
Relationships Between Variables (cont)
16
High
PERFORMANCE
Low
Low Moderate High
ANXIETY
17
Are the Following Relationships Positive or
Negative?

• GPA and Alcohol Consumption
• of sexual partners and of STDs
• SAT scores and freshman GPA
• hrs TV viewed and hrs studying

18
Two Ways of Studying Relationships

• Non-experimental method
• Experimental method

19
Non-experimental Method

• Behavior is observed as it naturally occurs
• Variables are measured only
• Examples

20
Problems

• Direction of cause and effect
• Does X cause Y?
• Or does Y cause X?
• Uncontrolled third variables
• Perhaps Z causes both X and Y
• If so X and Y will appear to be related

21
Experimental Method

• Addresses the problems of inferring cause and
  effect
• Manipulate the first variable and observe the
  effect on the second variable
• Control for all other variables

22
Effect of IV on the DV

• Does distraction cause poor performance on an
  exam?
• Independent Variable
• cause variable
• Manipulated first
• Dependent Variable
• effect variable
• Measured as a response to the IV

23
Causal sequence

• The IV comes first
• The DV is then measured to examine the effect of
  the IV
• Thus, X causes Y
• Y could not cause X

24
Control Other Variables

• Experimental Control
• Variables are kept constant
• Randomization
• Randomly assign participants to conditions
• Run the conditions of the study in a random order
• Some other variable could not cause the
  relationship between X and Y

25
Advantages of the Non-Experimental Method

• Real life situations
• Prediction
• Study aspects of people such as personality
  characteristics
• Can study variables that would be unethical to
  manipulate in a true experiment

26
Graphing the variables

• Independent Variable (X axis)
• Place the variable you identify as the cause on
  the X (horizontal) axis
• Dependent Variable (Y axis)
• Place the variable you identify as the effect
  on the Y (vertical) axis

27
Identifying IVs and DVs
IV
DV

• The effects of ________ on ________.

28
Validity

• Is something valid?
• Three ways of evaluating research in terms of
  validity

29
Construct Validity

• Were the variables I studied adequately measured
  or manipulated?
• Look at the operational definition of the
  variables that were studied

30
Internal Validity

• MOST IMPORTANT KIND OF VALIDITY!
• This differentiates b.s. from real findings
• It asks Can I infer (conclude) that change in
  variable X caused a change in variable Y?
• You get Higher internal validity with the
  experimental method. Why?

31
External Validity

• Can I generalize my results beyond this
  particular study?
• That is, can I generalize my results to other
  types of participants, other ways of studying the
  variables?

32
The End