Academic journal article The Journal of Speech-Language Pathology and Applied Behavior Analysis

Treatment of Chronic Aphasia with Errorless Learning Procedures: A Direct Replication

Academic journal article The Journal of Speech-Language Pathology and Applied Behavior Analysis

Treatment of Chronic Aphasia with Errorless Learning Procedures: A Direct Replication

Article excerpt

Single-subject experimental designs are often used to measure the effects of aphasia treatment. However, direct and systematic replications (Barlow & Hersen, 1984; Sidman, 1960) of original studies (e.g., Bardin Ayers, Potter & McDearmon, 1975) are uncommon or nonexistent in the aphasia literature (Basso & Caporali, 2004; Siguroardottir & Sighvatsson, 2003, 2005, and 2006). Perhaps one of the reasons for this is that language treatments have not been well-defined (e.g., Byng & Black, 1995; Robey, 1998). Most individual treatment studies have included poorly defined independent variables, thereby obscuring internal validity and rendering replications impossible (Greener, Enderby and Whurr, 2000; Jordan & Hillis, 2006). Definitions and operationalization of independent (treatment) variables and specification of treatment procedures is a necessary prerequisite for experimental replication. Replication of therapeutic effects is a prerequisite for advancement in any therapeutic field. Only with direct and systematic replications of single-subject experimental studies is it possible to ultimately determine which type of therapy is effective for what type of patient with what type of etiology and symptoms and in which particular situation (Barlow & Hersen, 1984; Hayes, Barlow, & Nelson-Gray, 1999). This is especially true when considering a small number of clients with the same etiological classification but with heterogeneous profiles of specific symptoms. This is the case in the field of aphasia because a clear relation between specific symptoms and underlying deficits has not yet been established despite attempts to do so with the newest technology (Hillis, 1989; Thompson, 1996).

Why specific interventions affect the performances of persons with aphasia and how different types of interventions affect those performances remain unknown. Treatment variables that can be linked directly to potential causes of specific symptoms remain undeveloped (Greener et.al, 2000), and the existing research (mostly group studies) does not permit a clear analysis of intervention effects. Group studies are limited because they only provide pooled group averages and no specific information at the individual level. For these reasons, single subject designs are a preferred strategy for studying treatment effects for individuals with aphasia. These designs offer good control over participant variables such as age, gender, type of disability, and others. They also allow the researcher to observe carefully any changes that may occur in a participant's performance during the treatment phase. For example, if indicated by the data, the treatment variables can be adapted to enhance the participant's performance (Siguroardottir & Sighvatsson, 2006). By using well defined treatment variables, this approach also allows for systematic replications (Barlow & Hersen, 1984; Sidman. 1960).

When developing treatments to support patients with Broca's aphasia, it is important to consider the different features of the condition and to focus on how a treatment may affect a particular feature. For example, one patient may have special difficulties naming while another may have problems only when reading. In fact the symptom profiles of patients are often quite unique and they change before the condition gets to be chronic (Cherney & Robey, 2001). Furthermore, when a treatment is being developed it is important that all treatment variables be clearly defined so that the same treatment can be assessed for its effectiveness across different patients with different symptoms.

Single subject research design has been widely used in the field of applied behavior analysis, particularly for evaluating the effects of treatments based on operant learning principles. Treatment based on these principles have been used with efficiency, effectiveness, and efficacy for teaching skills to people with learning disabilities, brain damage, psychiatric disorders and other impairments (for extensive review see Austin and Carr, 2000). …

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