Backward chaining used to teach a woman with aphasia to read compound words: A single case study.

Abstract

Introduction Broca's aphasia is an adult language disorder that is often acquired following a cerebral vascular accident (stroke) affecting the inferior gyrus of the left frontal lobe known as Broca's area (Doesborgh et al., 2004). The condition is characterized by a diminished vocabulary and by the slow, broken, and labored formation of sentences. Nouns are prominent in the speech of Broca's patients but other word types such as prepositions and adverbs seem harder for the patients to use (Carlson, 2001). By preserving content words and losing function words, persons with Broca's aphasia often produce speech that sounds labored and telegraphic (e.g., I.... glasses.... mall). Various approaches have been used to treat patients with Broca's aphasia including speech therapy, cognitive therapy, behavioral therapy, relaxation therapy, and others (Code, C., 2001). Most studies show improvements after treatment. Still, the development of an efficacious, effective and efficient treatment, one that reliably works better than others for specific patients with specific symptoms, remains to be established (Sigurdardottir & Sighvatsson, 2003, 2006b; Greener, Enderby & Whurr, 2000). 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 things while another may have problems reading. In fact the symptom profiles of patients are often quite unique, and, therefore, it is important to have an array of treatments to tackle an array of problems. 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. The existing research does not permit a clear analysis of intervention effects. Most individual treatment studies have included poorly defined independent variables, thereby obscuring internal validity and rendering replications impossible (Greener et al., 2000; Jordan & Hillis, 2006). Group studies have yielded an unclear picture of the effects of treatment for different individuals because they only provide pooled group averages and no specific information at the individual level. Single-subject design studies have rarely been replicated making it impossible to assess generality of results (Basso & Caporali, 2004; Sigurdardottir & Sighvatsson, 2003, 2005, 2006b). Single subject designs may be the most feasible strategy for studying treatment effects. These designs offer good control over participant variables such as age, gender, type of disability, and others. They also allow the researcher to carefully observe any changes that may occur in a participant's performance during the treatment phase. If indicated by the data, the treatment variables can then be adapted to enhance the participant's performance (Sigurdardottir & Sighvatsson, 2003, 2006b). For these reasons, single subject designs offer a unique way to carefully monitor any improvements made by a participant during the treatment. By using well defined treatment variables, this approach also allows for systematic replications (Barlow & Hersen, 1984; Sidman. 1960). 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. Within this framework, symptoms of impairment are viewed as behavioral deficits that can be ameliorated by teaching behaviors that a person is lacking. This framework offers a parsimonious approach to the treatment of aphasia (Austin & Carr, 2000). …