Single-Subject/Small-nResearch and Designs

Definition

• the hallmark of this style of research is that the individual’s data are not averaged with those of other participants

• the intensive study of the individual

• “Idiographic” research

Idiographic Research

• study of the individual to identify what is unique

• the unique individual can never be described by the “average” value

• non-statistical, no large sets of numbers

• look for consistency and reliability

• This is in contrast to “nomothetic” research

Nomothetic Research

• study of groups to identify what is typical

• Establish broad generalizations and general laws that apply to a diverse population

• The advent of nomothetic research was actually fairly recent

• Most early research in psychology was idiographic in nature

“Brief” History of Psychology

• Wundt (1879) and the “introspectionists”: looked at the individual’s “mental experience”

• Ebbinghaus (1885): studied the way in which associations are formed in memory, used only 1 subject, himself

• Thorndike (1898): search for intelligence in animals

• Fisher (1920)- work in agriculture led to the discovery of the field of statistics

• It became generally accepted that the nomothetic approach (statistics) was necessary to scientific research

• Problem: nomothetic method takes individual differences and defines them as error variance

• Skinner(1930s)-experimental analysis of behavior-a swing back to the study of the individual

• Looked for consistency of behavior across individuals

• Allport (1961)- need both idiographic and nomothetic approach to truly understand behavior

Two types of single-subject designs: Descriptive versus Experimental

Descriptive• describe the effect on an individual of a

specific treatment or simply describe a particular individual

• Can be a few pages or a book• May compare several case studies within one

piece of research• Can be from any area of psychology

Experimental

Applied Behavior Analysis

• introduce a particular factor (treatment) and measure its effect on some aspect of the individual’s behavior

• systematic application of treatment

Case Study Approach: a descriptive method

There are three methods of gathering data for a case study:

• Observation- direct observation of the subject• Interview- written or recorded responses to

questions from an interviewer• Archival records- stored documents such as

test scores, medical records, academic records

Case Study ExampleUlric Neisser (1981) Cognition

• case study of John Dean’s memory for the events & conversations surrounding Watergate

• Dean gave testimony in court about events and meetings prior to Watergate

• Dean seemed to be possess an amazing memory of events during that time

• As in all court proceedings, Dean’s testimony was recorded

• Later on, it was revealed that Nixon had secretly taped these meetings

• Dean did not know about these tapes

• Neisser took these tapes and compared them to the court documents of Dean’s testimony

What method of data collection did Neisser use??

Applied Behavior Analysis:Experimental single-subject design

• The application of principles of operant conditioning discovered in the lab to real life problems (B.F. Skinner)

• Each subject’s data is studied separately, not combined with any other subject’s data

• No means, variance, standard deviations, or NHST

Steps in a simple AB Behavior Analysis

• Stage 1: Baseline (A)- observe (measure) how the behavior is occurring before intervention/treatment. Rate of behavior before treatment

 • Stage2: Treatment (B)- introduce

treatment/intervention and continue to monitor behavior, looking for change

Example

• shy child in a preschool environment. Not interacting with peers or teachers, non-verbal

• want to encourage child to talk

• give this child a gold star to stick on a poster each time he speaks

• First monitor speech without treatment: baseline before treatment (A)

• Then begin to give gold stars as treatment (B) and monitor speech, see if speech increases

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• Did treatment (gold stars) increase rate of vocalizations?

• Could there be other reasons for an increase in speech?

• Think about potential threats to internal validity.

• Other designs are attempts to rule out these threats

ABAB Reversal Design• monitor baseline (A)

• apply treatment (B)

• withdraw treatment and return to baseline (A)

• reapply treatment (B)

• hence, “ABAB” design

Gold Star Example (again)

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Potential problems in an ABAB design

• ABAB rules out History and Maturation confounds

• But you have two potential issues surrounding the recovery of baseline during the second “A” phase

1. Failure to recover baseline in second “A” period: The behavior may not revert to baseline. Other factors in the environment may support the behavior change

2. It may be unethical to recover baseline if the behavior is dangerous to either the subject or others (self-injury behavior for example)

Multiple Baseline Designs• argue against History and Maturation threats• do not require recovery of baseline

Three Multiple baseline designs:

1. Multiple baseline across individuals (or “subjects”)

2. Multiple baseline across behaviors

3. Multiple baseline across situations

Multiple baseline across individuals

• compare several people (subjects)

• get a baseline for each person (subject) independently

• introduce treatment at different points in time for each person (subject)

• This allows an argument against History and Maturation

Example:Allison and Ayllon (1980)

• Traditional versus behavioral coaching• football skills• Traditional: verbal instructions, some

modeling, and if not correct then yelling, berating, punishment

• Behavioral: systematic verbal feedback, positive and negative reinforcement with verbal reinforcement

   For all three multiple baseline designs:

• the change in behavior for each person/behavior/situation should occur at the point in time that treatment is introduced for that person/behavior/situation

• This allows an argument against history or maturation as a “plausible alternative explanation”

Multiple baseline across behaviors

• use only one subject

• monitor several behaviors

• Switch from baseline to treatment at different points in time for each behavior

Example: Social skills training

• Michel Hersen & Alan Bellack, 1976

• patient in a psychiatric hospital, chronic schizophrenic

• monitored several social behaviors/skills

• eye contact, speech duration, number of requests

• all different aspects of being socially appropriate

Treatment• Four weeks of “social skills training” (treatment)

• Introduced training for each skill separately: first eye contact, then duration of speech, and then number of requests

• Showed video of social situation

• Subject responds to situation

• Researcher provides: Feedback on response and instructions on how to improve response (skills training) as “treatment”

• Example:• Working on eye contact

• Subject makes response to video situation

• Researcher gives feedback

• “That was better, but you still looked away at the end”

Data from one subject

Multiple baseline across situations

• look at one subject

• monitor one behavior

• do so in a variety of settings

Example:Kay, Harchik, and Luiselli (2006)

Problem

• George, a high school student

• autism with developmental delay

• drooling often/constantly, puddles on school work

• experiencing social rejection by other student

Treatment

Monitored drooling in three situations:

1. classroom (3 h/day)

2. vocational setting (2 h/day)

3. cooking class (1 h/day)

• Differential Reinforcement of Other Behavior (DRO)

• gave him small edible treat for each 5 min period with no drool

Achieving a Stable Baseline

• Baseline issues- Applied Behavior Analysis bases the argument for an effective treatment by looking for a change in behavior from some baseline level

• what if you cannot establish a “stable” baseline?

Problem Baselines

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Unstable Baseline

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Ascending baseline

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Descending baseline

• All of these are problematic. How can you achieve a stable baseline?

• Can look for the cause of the instability and control it.

• Can try to “wait it out” and it may become more stable over time

• Can average it out