The Experimental Approach

1
The Experimental Approach

• Chapter 3

2
Types of Research DesignsReview

• Case Study N 1
• Survey and/or Correlational Study Collect data,
  usually self-report, and relate.
• Naturalistic Observation Observe behavior in its
  natural setting.
• Archival Study Use pre-existing information
• Experiment Manipulated independent variable,
  control over extraneous variables.
• Quasi-Experiment Naturally occurring grouping
  variable, but analyzed like an experiment.

3
What is an Experiment?

• Systematic research study in which the
  investigator directly varies some factor (or
  factors) and holds all else _________and observes
  the results of the _______________.

4
The Psychological Experiment Key components -
Variables

• __________ something that can take on more than
  1 value

Example Sex Eye color Class standing Age Height
Weight Visualization SAT-Verbal Curiosity
Possible values Female, male Blue, brown,
green Fr, soph, jr., sr. 6, 19, 25, 70
(years) 60, 72, 84 (inches) 79, 101, 220
(lbs) 1.5, 2.0, 3.0 (secs) 500, 600 (scores) 40,
50, 60 (scores)
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The Psychological Experiment Key components -
Variables

• ______________________ the cause
• Variable that is _____________ by experimenter
• Different Types
• _____________ - different features in the
  environment that participants might encounter
  (Ex helping behavior study)
• ______________ - different tasks
  participants may perform (Ex problem solving
  experiment)
• _________________ - different instructions asking
  participants to perform tasks in certain ways
  (Ex memory experiment)

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The Psychological Experiment Key components -
Variables

• ________________ the effect
• Variable that is measured by experimenter.
• DV depends upon the independent variable
• A.k.a. the outcome variable
• Example rats caught per hour, of times
  someone offers help, number of errors on
  problems, of words recalled in 90 seconds

7
Example Scenarios Experiments

• Student volunteers given study drug. Half get
  mild caffeine, half get saline (nobody knows who
  gets what). Both take same exam the next day.
• IV?
• ____________________
• DV?
• ____________________

8
Example Scenarios Experiments

• Pilots use microcomputer to train communication
  skills. Half get to talk to simulated air
  traffic control while flying micro. Other half
  plays asteroids. All then fly full motion
  simulator.
• IV?
• ____________________________________
• DV?
• _____________________________________

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Key components - Variables (continued)

• _____________________
• A nuisance variable or variable that you did not
  manipulate but might influence the results of the
  experiment.
• Therefore, _______________________________________
  
• Example gender of experimenter

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Key components - Variables (continued

• _______________________
• An uncontrolled, extraneous variable that
  systematically co-varies with your IV (i.e. it
  changes at the same time your IV changes)
• Cant tell if observed differences are due to
  your manipulated variable of interest or if they
  are due to your unintentional _________________.

11
Examples of Confounding Variables

• Example 1 Influence of alcohol on risk-taking
  behavior
• IV Give one group soda and another group alcohol
• DV Risky behavior is define by of time one
  bets in blackjack
• See any problems?
• ____________________________
• ______________________________
• ___________________

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Examples of Confounding Variables

• Example 2 Influence of music on spatial
  abilities
• IV Recruit one group from architecture
  department to listen to music
  while performing spatial task, and recruit
  other group from business to perform in
  silence.
• DV Accuracy length of time to mentally rotate
  a series of objects.
• See any problems?
• ________________________________________________
  _

13
Another Example Study

• Goodmon Joseph want to know if Powerpoint is
  better than marker board for lecture. Goodmon
  uses Powerpoint in her class (Research Methods in
  Lakeland), and Joseph uses marker board for his
  class (Research Methods in Tampa). They look at
  the distribution of exam scores to see whether
  one class does better than another.

• IV?
• ________________________________________
• DV?___________________________________
• Confounds?______________________________

14
Variables cont

• Subject vs. manipulated variables
• _____________ already existing characteristics
• Examples ________________________
• Cannot manipulate directly so must select
  participants for different conditions by virtue
  of characteristics they already have

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Causation

• Cause
• Has implicit assumption of manipulation
• contextually dependent
• Effect-the difference between what would and what
  did happen

16
Causation

• Causal relationship-what evidence is needed
• John Stuart Mills Canons
• Method of agreement
• Method of difference
• Joint methods of agreement and difference
• Method of concomitant variation

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• Identified the necessary and sufficient
  conditions for the occurrence of an event
• -- Position of falsification
• -- Causation viewed as a large network of
  cause-and-effect relations

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The Psychological Experiment

• Criteria for identifying a causal relation
• Cause must ______________ the effect
• Cause must be___________ to the effect
• No other explanations must exist for the effect
• Definition of the psychological experiment
• Objective observation
• Of phenomenon that are made to occur
• In a strictly ____________situation
• Where one or more factors are varied and the
  other kept constant

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Advantages of the experimental method

• Causal inference
• Causal description
• Causal explanation
• control
• Ability to manipulate variables

20
Disadvantages of the experimental approach

• Does not test effect of ________________
  ____________age, weather, etc
• Artificiality
• Inadequate method of scientific inquiry

21
Experimental research settings

• Field experimentation
• Disadvantage-______________________
• Laboratory experimentation
• Strength is control over extraneous variables
• Weakness__________________

22
Validity of Experimental Research

• 4 ways that experimental research may be
  considered valid
• Uses __________properly
• Defines IV and DV in ___________________
• ____________results
• Free of ____________

23

• Internet experiments
• Advantages
• ________________________
• Bring experiment to participant
• ___________________
• Direct access to motivational confounding
• Cost savingslab space, equipment, etc
• Disadvantages
• ____________________
• Self-selection
• ___________________