This document discusses extraneous variables that need to be controlled in experiments to avoid confounding results. It describes four types of extraneous variables: physical, social, personality, and context variables. For each variable, it provides examples of how they can influence experiments and methods for controlling them, such as eliminating variables, using single-blind or double-blind experiments, cover stories, and balancing conditions across treatments. The goal is to establish constancy of conditions and control for demand characteristics, experimenter bias, and other unintended influences on experimental outcomes.

1. CHAPTER 8:
SOLVING PROBLEMS:
CONTROLLING EXTRANEOUS
VARIABLES
Reporter: Nikka Veniez Sunga

2. Extraneous Variable
-Variable that is not the focus of an experiment and that can
confound the result if not controlled

3. • PHYSICAL VARIABLES
• SOCIAL VARIABLES
• PERSONALITY VARIABLES
• CONTEXT VARIABLES

4. PHYSICAL VARIABLES
Aspects of testing conditions that need to be controlled

5. • ELIMINATION AND CONSTANCY
To make sure that an extraneous variable does not effect an
experiment, sometimes we just take it out– we eliminate it.
Constancy of conditions means that we keep all aspects of the
treatment conditions as nearly similar as possible.
• BALANCE
Distributing the effects of an extraneous variable across the
different treatment conditions of the experiment.

6. SOCIAL VARIABLE
The qualities of the relationships between subjects and
experimenters that can influence results.

7. • DEMAND CHARACTERISTICS
Aspects of the experimental situation that demand that people
behave in a particular way.

8. CONTROLLING DEMAND CHARACTERISTICS: SINGLE-BLIND EXPERIMENTS
Single Blind Experiment is an experiment in which subjects do not know
which treatment they are getting.
Placebo Effect is the result of giving subjects a pill, injection, or other
treatment that actually contains none of the independent variable.

9. CONTROLLING DEMAND CHARACTERISTICS: COVER STORIES
Cover Story a plausible but false explanation of the procedures in an
experiment told to disguise the actual research hypothesis so that
subjects will not guess what it is.

10. • EXPERIMENTER BIAS
The influence of what the experimenter does that creates
confounding in the experimenter

11. CONTROLLING EXPERIMENTER BIAS: DOUBLE-BLIND EXPERIMENT
An experiment in which neither the subjects nor the experimenter
know which treatment the subjects are in; used to control experimenter
bias.
*Rosenthal Effect/Pygmalion Effect

12. PERSONALITY VARIABLES
The personal characteristics that an experimenter or
volunteer subjects bring to the experimental setting

13. CONTEXT VARIABLES
Those that come about from procedures created by
environment, or context, of the research setting.