Chapter 7: Control

Question 1

What does the concept of control mean in experimental research?

Answer 1

any means used to rule out threats to the validity of research

• The concept of control is essentially a way of establishing that two individuals (or groups, or conditions) are identical except for the variable of interest.
• When that is the case, the research is internally valid.

Question 2

control condition:

Answer 2

a condition in a within-subjects design experiment that does not contain the experimental manipulation

Question 3

within-subjects experiment:

Answer 3

research design in which each subject experiences every condition of the experiment

Question 4

between-subjects experiment:

Answer 4

research design in which each subject experiences only one of the conditions in the experiment

Question 5

Control experiment:

Answer 5

meaning allows one to conclude that a dependent variable is associated with an independent variable and not with any other variable.

Question 6

Experimental control:

Answer 6

facilitates drawing this conclusion by so limiting the number of variables operating in the situation and their range of values that the conclusion is clearer.

When one has so limited the sources of variability in an experiment that the behavior becomes highly predictable, one has achieved experimental control.

Skinner pecking pigeon example of pecking with green light and predicting it would not peck with red light

Question 7

several specific strategies for achieving control

Answer 7

• Control in the Laboratory
• • Laboratory research remains the ideal when it is feasible, simply because it offers the most control. Selecting the maximum level of control possible when considered with the nature of the problem is the ideal.
• • The Research Setting as a Preparation
• • A preparation is an environment that is selected or constructed for a particular purpose.
• experimental equipment, the method of testing, and the location of testing, as well as the subject used in the study
• Famous Milgram experiment with the electro shocks
• • Instrumentation of the Response as Control
• • Software detecting speech in PD paper
• Beck Anxiety Inventory. The Minnesota Multi- phasic Personality Inventory, functional magnetic resonance imaging (fMRI), and Stevens’s direct psychophysical scaling methods are other excellent examples.

Question 8

Briefly describe the strategy of subject as own control.

Answer 8

• variation caused by differences between people is greatly reduced
• common in many areas of psychology, particularly in the study of sensation and perception
• if enough time is allowed between conditions, there is unlikely to be an important carryover between conditions.

Question 9

limitations of this strategy of subjects as own control

Answer 9

• once the participant has learned something by one method, learning the same problem again by using a different method is impossible
• contrast effects exist between the conditions of the experiment, so that experiencing one condition may carry over and influence the response to another condition
• if magnitude of reward is the independent variable, subjects who experience a large reward (say, $200) first may respond less to a small reward (say, $20) than they would have if only the small-reward condition had been received.

Question 10

ONLY USE within control when:

Answer 10

• 1. Using subjects as their own controls is logically possible.
• 2. Participating in all conditions of the experiment will not destroy the naiveté of the subject.
• 3.Serious contrast effects between conditions will not be present

Question 11

random assignment:

Answer 11

unbiased assignment process that gives each subject an equal and independent chance of being placed in every condition

Question 12

matched groups

Answer 12

an experiment where the subjects are matched based on a particular variable and then put into groups. By matching subjects, the researcher is creating equivalent groups for their study.

chance alone can mess it up so there’s a need to match the groups evenly

DO A PRETEST TO MAKE SURE NOONE KNOWS ABOUT THE VARIABLE ANY MORE THAN ANYONE ELSE

Question 13

matching procedure

Answer 13

PROCEDURE

find the two children with the poorest math skills and randomly place one in Group A and the other in Group B.

You would repeat this procedure until you had paired off all the children.

Even when you have matched your subjects, you must still randomly allocate the members of the pairs to conditions.

Question 14

nuisance variable

Answer 14

a condition in an experiment that cannot easily be removed and so is made an independent variable as a means of control

• Building these nuisance variables into your study allows you to measure their effects and to examine the effects of your independent variable
• Nuisance variables should not be confused with confounded variables. A confounded variable is one that varies with the independent variable. A nuisance variable is treated as a second independent variable that is varied separately from the first one.

Question 15

statistical control:

Answer 15

mathematical means of comparing subjects on paper when they cannot be equated as they exist in fact

Question 16

How is statistical control used as a strategy for achieving control?

Answer 16

• One application:
• What if you are testing the effect of a learning method on 2 groups and 1 group had a lower IQ, stats would allow you to measure proportionately whether the method was effective by taking into consideration the difference in IQ levels of both groups

Question 17

2 types of replication and why

Answer 17

• Direct replication occurs when someone repeats essentially the identical experiment in an attempt to obtain the same results.
• seldom carried out because finding exactly the same thing as someone else did brings little glory.
• More specifically, it is difficult to get grants for replications, journals tend to avoid publishing such research, and professors who spend time replicating other people’s work do not get promoted.
• Direct replication is usually attempted only when systematic replication has failed.
• Investigators then go back and repeat the original method more exactly to pinpoint the source of the difference in results.
• Systematic replication occurs when Researcher B says, “If A’s theory is correct, then the following should happen.” Then B performs an experiment different from A’s but based on it. If A’s results and theory are correct, B should find a result that supports the theory
• Researcher B will do an experiment similar to Researcher A’s but with different types of subjects, with different values of the stimulus, or with different ways of measuring the theoretical concepts.
• All of these approaches are considered systematic replication.
• As long as results consistent with A’s are found, A’s original experiment is supported by B’s work.