Single Subject Research (Richards et al.) Chapter 8

Multiple Baseline Across Behaviors Design Hargrove, P. M., Roetzel, K., & Hoodin, R. B. (1989). Modifying the prosody of a language-impaired child. Language, Speech, and Hearing Services in the schools, 20,

Featuredescription Type of DesignMultiple baseline across behaviors Goal of studyDetermine if a behaviorally based treatment can affect or modulate prosody of a child with language- impairments SubjectSix-year-old male receiving services for language dysfluencies SettingThe child’s home Dependent variableThe prosodic performance of the child Independent variablePositive verbal feedback, token reinforcement, and a variety of cues along with specific training Results and outcomesThe performance by the subject on the probe items reached a 78% level of accuracy on two of behaviors and 67% on the third over the 18 training sessions that were implemented over a 9-day period

Across Behaviors Design The intervention was sequentially applied as the criterion level of performance was met on the preceding target behavior. Treatment was also discontinued with a target behavior once criterion was achieved. Why using an across behaviors design for this study? Permits performance on the three speech parts (subjects, verbs, objects) to be treated as separate variables. The lack of covariance among the targeted responses before implementation of the training procedure strengthens the argument for internal validity.

Limitations of the Study The lack of identification of the training components or combination of components that might have been responsible for changes (loose training). The gains were not fully maintained. suggestions includes implementing a longer training phase, more vigorous criterion, or addition of a maintenance phase.

Multiple Baseline Across Subjects Design Yoder, P. J., Yarren, S. F., Kim, K., & Gazdag, G. E. (1994). Facilitating prelinguistic communication skills in young children with developmental delay: II. Systematic replication and extension. Journal of Speech and Hearing Research, 37, This section is focused only on the first hypothesis among 3.

Featuredescription Type of DesignMultiple baseline across subjects Goal of studyDetermine effectiveness of the modified milieu method for increasing intentional requests SubjectFour children between ages 21 and 27 months with mental retardation SettingUniversity-based early intervention program Dependent variableSubjects’ behavior for intentional prompted and self-initiated requests and other intentional communication and preintentional signals Independent variableModified milieu teaching approach Results and outcomesThe modified milieu teaching approach is an effective method for increasing intentional questing and facilitating generalized communication in the subjects’ interactions with their mothers

Across subjects Design The researchers used abrupt changes in the level of responding and slope of the data path as indicators of intervention effects rather than a specific criterion level to determine when to implement the intervention with the next subject. Why using an across subjects design for this study? It was easier to observe the effects of the intervention across subjects using this design. Other designs (e.g., withdrawal design) would have been inappropriate. Once the requesting had increased, it is difficult to reverse this behavior in order to demonstrate a functional relationship. Staggered introduction of the intervention helped build a strong case for verification and replication within the design itself. Based on previous research conducted in the area of the milieu approach, it was expected before the study that there would be a functional relationship between the intervention and the subjects’ performance.

Limitations of the Study It was difficult to get the mothers into the clinic for the intervention sessions. The effects of the generalization with the mothers were not expected to be immediate due to the level of retardation of the students. Suggestions: Future research should seek an extended study using control and experimental groups. Although small groups are a strength of single subject research designs, such a small group (4 subjects) can affect degree of confidence in the generalizability of the intervention.

Multiple Baseline Across settings Design Cushing, L. S., & Kennedy, C. H. (1997). Academic effects of providing peer support in general education classrooms on students without disabilities. Journal of Applied Behavior Analysis, 30,

Featuredescription Type of DesignMultiple baseline across settings Goal of studyPeer support provided by students without stabilities to students with disabilities will have positive effects on academic engagement and associated measures for the peers without disabilities SubjectTwo 11-year-old students, one student without disabilities (Louie)and one with moderate intellectual disabilities (Leila) SettingSuburban intermediate school with 1,100 students from diverse backgrounds; English, science, and social studies classes

Table Continued Featuredescription Dependent variablePercentage of time academically engaged for Louie, defined as involvement in ongoing classroom activities and/or work-related assignments Independent variableThe peer support system of academic engagement that included participation with student with disabilities and training and/or supervision from special education and general education teachers Results and outcomesThe percent of time in which Louie was academically engaged increased during the periods he was serving as a peer support for Leila

Across settings Design Why using an across settings design for this study? Using across settings design was more convincing, than using only one setting, to demonstrate a functional relationship between independent and dependent variables. The multiple baseline design offered the advantages of providing intervention in all settings of need without having to withdraw treatment.

Limitations of the Study Because the sample of students was so selective, the robustness of the findings requires systematic replication across a variety of students without disabilities. The question that hasn’t been answered is that whether positive effects would occur for students who are already performing at high levels in general education classes.

Issues with Multiple Baseline Designs The time and resources are sometimes problematic. There may be no other behaviors, settings, or individuals available who are in need of the intervention. At times, the need to identify an effective intervention as quickly as possible is very important. In this case, alternating treatments design may be appropriate.