Single-Subject

Designs

What is a single-subject (small-n)

design?

Not necessarily a single subject

Subject acts as their own control

Subject is exposed to each condition of the experiment

Repeated Measures

Within each condition, a dimension of behavior is measured multiple

times

Data are analyzed for each subject separately

Study of the

individual

B.F. Skinner

“Free-operant”

Cumulative records/rate of

responding

What is the dependent variable?

Dimensions of behavior

Rate

Number of steps per hour

Cigarettes smoked per day

Number of head hits per minute

Duration

Time spent working on homework

Time spent out of seat

Intensity

Decibels (loudness)

Areas of Research & Treatment

Treatment for individuals on the autism spectrum, with ID, and DD

At UNCW (just a few examples)

Drugs and impulsivity (Dr. Hughes and Dr. Pitts lab)

Treatments for pediatric feeding disorders (Dr. Bachmeyer’s lab)

Treatments for severe problem behavior (Dr. Van Camp’s lab)

Other interesting areas of research

Cigarette smoking cessation (Kurti & Dallery, 2014)

Disruptive behavior at dentist (O’Callaghan, Allen, Powell, & Salama, 2006)

Environmental enrichment in zoos and aquariums (Mehrkam & Dorey, 2014)

Small-n Example

Wunderlich & Vollmer (2015)

IV: Baseline (control), Intervention (RIRD)

DV: Duration of vocal stereotypy- converted to percentage

Example participant: Ariel

Baseline -> 6 days

Intervention -> 5 days

Baseline -> 4 days

Intervention -> 3 days

ABA Reversal

Design

A = Baseline

B = Intervention

A = Return to baseline

Baseline logic

Did the intervention work for

Ariel?

Pe

rce

nta

ge

of

Inte

rve

ntio

n T

ime

En

ga

ge

d in

Vo

ca

l Ste

reo

typ

y

Pe

rce

nta

ge

of

En

tire

Se

ssio

n

En

ga

ge

d in

Vo

ca

l Ste

reo

typ

y

Graphs adapted from

Wunderlich & Vollmer (2015)

How do we minimize threats to

internal validity?

Experimental control (control of the environment)

Demonstrate a reliable effect

Eliminates or reduces the possibility of confounding variables

Repeated measures

Use of various designs (e.g., multiple baseline)

Counterbalancing

… and what about the external validity of small-n experiments?

Visual Analysis-What do you look for?

Stability is key

Trends

Changes in level

Was the intervention

successful for Participant A?

B? C?

Graphs from Cooper, Heron, & Heward

(2007)

References

Cooper, J. O., Heron, T. E., & Heward, W. L. (2007). Applied behavior analysis, 2nd ed. Upper Saddle River, NJ: Pearson Prentice Hall.

Kurti, A. N., & Dallery, J. (2014). A laboratory-based evaluation of exercise plus contingency management for reducing cigarette smoking. Drug and Alcohol Dependence, 144, 201–209.

Mehrkam, L. R., & Dorey, N. R. (2014). Is preference a predictor of enrichment efficacy in Galapagos tortoises (Chelonoidis nigra)? Zoo Biology, 33(4), 275–284

O’Callaghan, P. M., Allen, K. D., Powell, S., & Salama, F. (2006). The efficacy of noncontingent escape for decreasing children’s disruptive behavior during restorative dental treatment. Journal of Applied Behavior Analysis, 39, 161–171.

Wunderlich, K. L., & Vollmer, T. R. (2015). Data analysis of response interruption and redirection as a treatment for vocal stereotypy. Journal of Applied Behavior Analysis, 48(4), 749–764.

THANK YOU!

Questions?