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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?