Chapter 12: Single subject design

Question 1

Name several prominent psychologists in history who used single subjects in psychological research. Briefly describe their areas of research

Answer 1

• Fechner invented the basic psychophysical methods that are still used to measure sensory thresholds and discovered principles of psychophysics that are still taken seriously
• Hermann Ebbinghaus did his experimental work on memory. Following Fechner’s example, Ebbinghaus used himself as his own participant
• Pavlov did his pioneering work on conditioning with individual dogs as subjects

Question 2

clinical significance:

Answer 2

the practical importance of a result

Question 3

power:

Answer 3

the probability that a statistical test will find a significant differ- ence when a difference actually exists in the population

Question 4

What are the advantages of the single-subject approach?

Answer 4

• single-participant design act as their own controls, avoids the possibility that the average picture is a distortion of the behavior of the individual participants
• An experiment that employs large groups of participants will be likely to discover that an independent variable has an effect even if the effect is a minor one leading to low statistical significance
• In a single-participant experiment, the effect of a minor variable is less likely to be discovered so the experimenter will not be distracted by it
• researcher can spend time reducing variability so that the effect of a given variable will be maximized, instead of spending time testing more participants
• Avoids Ethical and Practical Problems in light of having a control group who does not get the anti suicide psychological training
• If there aren’t enough people to test, then a single subject will be useful
• Flexibility in Design
  
  • If the design is a single-subject one, the experiment can be modified on the spot by switching reinforcers or by altering the instructions
  • when a large change occurs in the participant’s behavior that the experimenter suspects is caused by an outside event rather than by the experimental manipulation. the experimenter can immediately switch the conditions

Question 5

What are the disadvantages of the single-subject approach?

Answer 5

doesn’t work in all cases:

For example, the only way to decide if having been abused as children causes adults to be child abusers themselves is to compare large groups of individuals

Question 6

AB design:

Answer 6

also called a comparison design; single participant research design that consists of a baseline followed by a treatment

Question 7

disadvantage of AB design

Answer 7

The difficulty with an AB design is that you will not know whether other variables that may have coincidentally changed at the same time that the treatment was administered actually produced the change in behavior.

Question 8

ABA design:

Answer 8

research design that includes a baseline period, a treatment period, and a subsequent withdrawal of treatment

Question 9

how does ABA rectifie problem with AB design:

Answer 9

argument that the treatment is the cause of the change is considerably strengthened if the treatment is withdrawn after a period of time and the behavior shows a return toward the baseline

Question 10

Problems associated with ABA

Answer 10

• effect of the manipulation may not be fully reversible
  
  • lesion of the brain
• you may want to leave the participants in the new condition rather than return them to their original state.
  
  • Treatments involving weight control, phobias, and compulsive behaviors are typical examples in which it would be unethical and undesirable to withhold treatment until the patient returned to the original state.

Question 11

when is ABAB favorable?

Answer 11

• Superior when the B is a more favorable condition to leave the subject in
• Example in book on self-inflicted injuries and exercise to release endorphin
• The reversal feature of the design strengthens the conclusion that the exercise had the effect of decreasing the self-injurious behavior

Question 12

baseline:

Answer 12

the measure of behavior before treatment that establishes a reference point for evaluating the effect of treatment

Question 13

Why is it necessary to maintain a stable baseline before treatment begins?

Answer 13

• to compare the behavior that occurs before and after the introduction of the experimental manipulation.
• The behavior before the manipulation must be measured over a long enough time span to obtain a stable baseline against which the later behavior can be measured
• It measures the current level of the behavior,
• and it predicts what the behavior would be in the future if no treatment were administered

Question 14

What is a multiple-baseline design? Under what conditions is this design useful?

Answer 14

multiple-baseline design: research design that introduces different experimental manipulations to see if changes coincide with manipulation.

useful if the expected behavior change is irreversible, because you don’t have to remove the treatment to demonstrate causality

Question 15

Three types of multiple-baseline designs exist:

Answer 15

(1) across subjects,
(2) across behaviours, and
(3) across settings.

As in the single-subject designs, the first phase of the multiple-baseline design involves recording baseline behaviour. For instance, in the multiple-baseline design across behaviours, different periods of baseline data are gathered for several different behaviours on one subject.

Question 16

Three types of manipulation in multiple baseline design:

Answer 16

behaviors, subjects, and settings

Question 17

eg of multiple baseline design in single subject for setting, which can be place, time, situation

Answer 17

• adhd
• impulsivity in the classroom
• impulsivity at home
• impulsivity in music therapy session

then see if ritalin helped in all 3 settings or if some other factor helped it

delay start for susequent start times of intervention

Question 18

multiple-baseline across behaviors:

Answer 18

design that measures the effects of implementing a treatment following baseline measurement to multiple behaviors in the same subject sequentially, so that each untreated behavior’s baseline acts as a control for those that have been treated

Question 19

multiple-baseline across subjects:

Answer 19

design that measures the effects of implementing a treatment following baseline measurement to multiple subjects sequentially, so that each untreated subject’s baseline acts as a control for those that have been treated

Question 20

multiple-baseline across settings:

Answer 20

design that measures the effects of implementing a treatment following baseline measurement of a subject’s behavior in multiple settings sequentially, so that each untreated setting’s baseline acts as a control for those that have been treated

Question 21

changing-criterion design:

Answer 21

research design that introduces successively more stringent criteria for reinforcement to see if behavior change coincides with the changing criteria

• Suppose that a child is unable to sit still in class.
• The teacher may reward the child for sitting still for five minutes at a time until the performance becomes stable.
• Then the criterion may then be increased in steps, perhaps to 10 minutes, later to 15, and so forth.
• The behavior at each criterion becomes the baseline against which to evaluate the effect of the manipulation at the next criterion.
• It is important to note that if a participant cannot attain the next criterion, one must step back to a lower level of effective performance. A less substantial increase in criterion can then be implemented

Question 22

Under what conditions is changing criterion design useful?

Answer 22

useful when the behavior change is irreversible or when a return to the initial base- line is not desirable

Question 23

two areas of psychology in which the single-subject approach is commonly used

Answer 23

• psychophysical research (to measure light thresholds example)
• And behavioral (pigeons pecking)