Single-Case Experiments

Single-Case Experimental Design: ABAB   (A = noncontingent; B = contingent)

The ABAB design implies that the behavior is under control of the contingency. Removal of the contingency (the second A in the ABAB design) and its reinstatement (ABAB) will test whether the behavior is maintained in the absence of the contingency.

Clinical Treatment

Participants:  10 academicians (5 females and 5 males) who sought treatment of writing blocks. Ages ranged from 31 to 55 years.

Clinical Sessions: hour-long, individual weekly sessions. Initial session the study is described, individuals agree to self-monitor and chart writing output on a daily basis, and to use external contingencies (to be specified later). All agreed to set up stimulus control conditions for writing - a quiet comfortable room where nothing is done except writing, where five daily writing periods per week could be regularly scheduled. Agreed to remain in treatment for 22 consecutive weeks.

Procedures:

1. Baseline stage (ABAB, 2-3 weeks), no external contingencies. The length of the baseline was partially determined by the "subject's need to talk about their writing problems" (p. 184). Credit for writing was based on the number of finished typed pages per day.  Encouraged to count up to one page per day that was a rewrite. All writing was verified by the therapist/experimenter.  Participants were advised to set a goal of three pages per day; to write in a steady manner each day rather than in spurts; and to maintain writing even during times of vacations and heavy workload periods.

2.  1st contingency period (ABAB, 35 to 75 scheduled writing days). Contingency: each participant wrote five $15 personal checks made out to an organization they had chosen as "hated."   The checks would be automatically mailed by a third party following every working day where the goal for writing output was unmet. The goal for all participants was set at 3 pages per work session.  (You could be excused from a work session if you called the therapist with a legitimate reason, this occurred in 3 instances.)  Stability criterion: a minimum of 30 working days and producing at goal level for 10 consecutive scheduled days. 

3. Removal of external contingencies (ABAB, 10 to 38 working days). Non-contingency: Any remaining checks were returned. No external contingencies were used. Stability criterion: writing below goal levels for 10 consecutive scheduled days.

4. 2nd contingency period (ABAB). Contingency:   Same as for 1st contingency period. Stability criterion: meeting a writing goal for 10 consecutive days.

Experimental Treatment

Participants: 10 academicians (6 females and 4 males) who agreed to be a research study related to writing blocks. Selected in an attempted to match demographic characteristics of participants in the clinical treatment condition.

Experimental program: No reference to therapy, treated as experimental subjects.  The initial session described the research.  Weekly sessions were about 15 minutes long.  Some (nine total) weekly sessions were excused. The topic of the meeting was to examine charts, verify written materials, and discuss the mechanics of the procedures. "Attempts by subjects to discuss personal problems or to lodge complaints about writing were politely rebuffed with a comment to this effect: 'Our goal is simply to help you arrange the working conditions that will help you be a productive writer'" (p. 185).

Procedures: The same four stages as the clinical treatment.   The sessions were of fixed length: 15, 35, 35 and 35 scheduled working days.

Attrition: An additional three participants in each condition dropped out without completing the four phases of the design.

Writing output: Individual case histories

See Figure 1 for charts of the writing output (# of pages written per session) for 5 clinical participants.

1.  What is the stability of writing for the baseline phase (ABAB)? Were there any trends in the writing output during this phase? How would you summarize the effects of the stimulus control procedures used in this phase of the study?

2.  What was the output in the first contingency phase (ABAB) relative to the baseline phase in terms of (a) the number of pages written and (b) the stability of the writing output? How many "failures" did case "A" have during the this period? Were there any trends in the writing output during this phase?  Was the impact of the contingency immediate, or was there a gradual change in behavior as a result of instituting the contingency, or was the effect immediate?

3.  What was the output in the second non-contingency phase (ABAB) relative to the previous contingency phase?   Was the writing process "internalized" by this combination of clinical treatment and contingency management? How stable was the writing output during this phase?

4. What was the output of the second contingency phase (ABAB) relative to the earlier phases?  What is your conclusion about the importance of the contingency for these clinical participants?  Was there any other data about writing productivity offered in this paper?

Writing output: Group data

See Figure 2 for output summaries for each treatment group for each of the 4 contingency-noncontingency periods.

In keeping with the behaviorist ideal that if the effects of contingencies on behavior are sufficiently strong one does not need statistics to describe the results, there is not a single p value reported in this paper.  What are your conclusions from Figure 2 with respect to the following questions:

1.  Did clinical treatment add to the effectiveness of the behavioral contingencies? 

2.  Did the first set of behavioral contingencies lead to an internalization of the writing productivity?

Would you prefer to see a t-test or an analysis of variance for this data?

Conclusions

Would you like me to hold your checks?

This insightful single case study stands on its own merits.  I recommend it to you.

Boice, R. (1983).  Experimental and clinical treatments of writing blocks. Journal of Consulting and Clinical Psychology, 51, 183-191.

Upper, D. (1974). The unsuccessful self-treatment of a case of "writer's block." Journal of Applied Behavior Analysis, 3,497-498.

Whitley, B. E., Jr. (1996). Principles of research in behavioral science. Mountain View, CA: Mayfield. (pp. 319-356).