Flexibility of single-subject experimental designs. Part I: Review of the basics of single-subject designs

The discussion in this article is directed at a brief review of the basic components of single-subject experimental designs. It sets out to present some of the technical and practical advantages in developing single-subject designs to evaluate potential treatment variables and treatments. The point is made that the designs are specifically structured for applied, intervention research. In addition to explaining how the basic AB components function to allow for a controlled evaluation, a short review is included of other factors important to the scientific method such as operational definitions, reliability, repeated measures, and internal and external validity. The article serves as a foundation for the following two articles that are directed at demonstrating the flexibility of single-subject experimental studies.     

The effect of a therapy dog on the communication skills of an adult with aphasia

Little evidence-based research has been published within the field of communication disorders on the role of dogs as catalysts for human communication. This single participant study, a point of entry into this realm of research, explores the effects of a therapy dog on the communication skills of a patient with aphasia receiving intensive speech and language therapy within a rehabilitation setting. The researchers conclude that the presence of the dog does have the potential to stimulate both overt social-verbal and social-nonverbal communication. LEARNING OUTCOMES: As a result of this activity the reader will be able to (1) describe the beneficial role of dogs to serve as catalysts for human communication (2) describe ways in which a person with aphasia may be assisted by a therapy dog and (3) become familiar with an animal-assisted therapy (AAT) program set-up for patients with communication disorders within a rehabilitation setting.     

Measuring and inducing brain plasticity in chronic aphasia

Brain plasticity associated with anomia recovery in aphasia is poorly understood. Here, I review four recent studies from my lab that focused on brain modulation associated with long-term anomia outcome, its behavioral treatment, and the use of transcranial brain stimulation to enhance anomia treatment success in individuals with chronic aphasia caused by left hemisphere stroke. In a study that included 15 participants with aphasia who were compared to a group of 10 normal control subjects, we found that improved naming ability was associated with increased left hemisphere activity. A separate study (N = 26) revealed similar results in that improved anomia treatment outcome was associated with increased left hemisphere recruitment. Taken together, these two studies suggest that improved naming in chronic aphasia relies on the damaged left hemisphere. Based on these findings, we conducted two studies to appreciate the effect of using low current transcranial electrical stimulation as an adjuvant to behavioral anomia treatment. Both studies yielded positive findings in that anomia treatment outcome was improved when it was coupled with real brain stimulation as compared with a placebo (sham) condition. Overall, these four studies support the notion that the intact cortex in the lesioned left hemisphere supports anomia recovery in aphasia. LEARNING OUTCOMES: Readers will (a) be able to appreciate the possible influence of animal research upon the understanding of brain plasticity induced by aphasia treatment, (b) understand where functional changes associated with anomia treatment occur in the brain, (c) understand the basic principles of transcranial direct current stimulation, and (d) understand how brain stimulation coupled with aphasia treatment may potentially improve treatment outcome.     

Flexibility of single-subject experimental designs. Part II: Design selection and arrangement of experimental phases

The purpose of this paper is to present a taxonomy of single-subject experimental designs and discuss relevant examples that underscore the versatility and flexibility of this approach to clinical research. The proposed taxonomy serves as a heuristic model that may facilitate an understanding of single-subject experimental designs. Four general evaluation strategies employed in applied research--treatment-no treatment comparison, component assessment, treatment-treatment comparison, and successive level analysis--are discussed within this schema. Each of these evaluation strategies is related to commonly posed clinical research questions, and published examples of design options that address these questions are presented. Throughout the discussion basic considerations relating to appropriate design selection are reviewed.     

Validation of the SADL questionnaire

OBJECTIVE: To cross-validate the psychometric characteristics of the Satisfaction with Amplification in Daily Life (SADL) questionnaire (Cox & Alexander, 1999), and to explore the SADL's construct validity. DESIGN: Thirteen private practice Audiology clinics each distributed SADL questionnaires, by mail, to 20 adults who had recently obtained hearing aids. The completed questionnaires were returned to a central site and subject anonymity was assured. There were 196 usable responses. RESULTS: Psychometric characteristics of the items were found to be very similar to those reported previously. Thus, the internal validity of the instrument was strongly supported. The assumption that the SADL quantifies satisfaction by assessing its components was evaluated by examining the relationship between SADL scores and scores on a traditional single-item satisfaction measure. A logical and statistically significant relationship was seen between the two measures, thereby supporting the construct validity of both types of data. For private-pay clients, satisfaction scores were very similar to the interim norms published by Cox and Alexander (1999). However, clients whose hearing aids were partly or fully purchased by insurance or benefits programs tended to be more satisfied than interim norms for third-party pay clients derived 5 yr ago. For most types of clients, there was a tendency toward more satisfaction in the Negative Features subscale than observed in our previous research. CONCLUSIONS: Both construct and internal validity of the SADL questionnaire were supported by this research. The previously published interim norms appear to be mostly appropriate for private-pay clients, but might require adjustment in the Negative Features subscale. Further research is needed to explore the relationship between satisfaction and device purchase issues (third-party versus private pay).     

Flexibility of single-subject experimental designs. Part III: Using flexibility to design or modify experiments

The purpose of this paper is to present clinical researchers with viable alternatives to basic, prototypical single-subject experimental designs. The availability of these alternatives is a product of the flexibility inherent in the application of these designs. Two general types of flexibility are discussed: a priori flexibility, as in combining designs in one study and ad hoc flexibility in which a design is modified during the course of a study. The flexibility afforded by the designs provides the opportunity to fashion individual experimental designs for specific research problems addressed. A review of the clinical research literature published during the last 10 years revealed that the flexibility of these designs has been underutilized. The benefits that can derive from using the potential flexibility of the designs are described, and specific suggestions are made for incorporating flexibility into clinical research.     

我国失语症治疗研究的计量学分析

目的对国内失语症治疗研究进行计量学分析,了解失语症治疗的研究前沿和趋势。方法采用文献研究方法,在中国知网(CNKI)数据库中输入检索式:主题词搜索为失语症,主题词下搜索为康复、治疗、干预、疗法、训练,采用Cite Space软件对文献作者、机构、关键词进行计量学分析。结果本研究共检索214篇文献。首篇文章发表于1992年,2004年达到第一高峰期(15篇),其后波动明显,2014年发文量(17篇)最高。暨南大学附属第一医院与首都医科大学宣武医院专业团队在此领域发文最多。脑损伤、meta分析、神经机制、脑卒中、脑卒中后、重复经颅磁刺激、计算机辅助、经颅直流电刺激、运动性失语、语言病理学为失语症治疗研究的热点。脑卒中、重复经颅磁刺激、经颅直流电刺激为失语症治疗的研究前沿与趋势。结论我国失语症治疗研究领域的核心作者群尚未形成,对于失语症研究尚需大量专业人员进行深入探索。     

Translational research in aphasia: from neuroscience to neurorehabilitation.

PURPOSE: In this article, the authors encapsulate discussions of the Language Work Group that took place as part of the Workshop in Plasticity/NeuroRehabilitation Research at the University of Florida in April 2005. METHOD: In this narrative review, they define neuroplasticity and review studies that demonstrate neural changes associated with aphasia recovery and treatment. The authors then summarize basic science evidence from animals, human cognition, and computational neuroscience that is relevant to aphasia treatment research. They then turn to the aphasia treatment literature in which evidence exists to support several of the neuroscience principles. CONCLUSION: Despite the extant aphasia treatment literature, many questions remain regarding how neuroscience principles can be manipulated to maximize aphasia recovery and treatment. They propose a framework, incorporating some of these principles, that may serve as a potential roadmap for future investigations of aphasia treatment and recovery. In addition to translational investigations from basic to clinical science, the authors propose several areas in which translation can occur from clinical to basic science to contribute to the fundamental knowledge base of neurorehabilitation. This article is intended to reinvigorate interest in delineating the factors influencing successful recovery from aphasia through basic, translational, and clinical research.     

Evidence-based systematic review: effects of intensity of treatment and constraint-induced language therapy for individuals with stroke-induced aphasia

PURPOSE: This systematic review summarizes evidence for intensity of treatment and constraint-induced language therapy (CILT) on measures of language impairment and communication activity/participation in individuals with stroke-induced aphasia. METHOD: A systematic search of the aphasia literature using 15 electronic databases (e.g., PubMed, CINAHL) identified 10 studies meeting inclusion/exclusion criteria. A review panel evaluated studies for methodological quality. Studies were characterized by research stage (i.e., discovery, efficacy, effectiveness, cost-benefit/public policy research), and effect sizes (ESs) were calculated wherever possible. RESULTS: In chronic aphasia, studies provided modest evidence for more intensive treatment and the positive effects of CILT. In acute aphasia, 1 study evaluated high-intensity treatment positively; no studies examined CILT. Four studies reported discovery research, with quality scores ranging from 3 to 6 of 8 possible markers. Five treatment efficacy studies had quality scores ranging from 5 to 7 of 9 possible markers. One study of treatment effectiveness received a score of 4 of 8 possible markers. CONCLUSION: Although modest evidence exists for more intensive treatment and CILT for individuals with stroke-induced aphasia, the results of this review should be considered preliminary and, when making treatment decisions, should be used in conjunction with clinical expertise and the client's individual values.     

The trouble with nouns and verbs in Greek fluent aphasia

In the past verb retrieval problems were associated primarily with agrammatism and noun retrieval difficulties with fluent aphasia. With regards to fluent aphasia, so far in the literature, three distinct patterns of verb/noun dissociations have been described for individuals with fluent anomic aphasia in languages with different underlying forms; better verb retrieval, poorer verb retrieval and equal retrieval difficulties for verbs and nouns. Verbs and nouns in Greek are considered of similar morphological complexity thus it was predicted that anomic aphasic individuals would suffer from a non-dissociated impairment of verbs and nouns. Problems with verbs and/or nouns may arise at any stage in the process of lexical retrieval, i.e. lexical-semantic, lemma, lexeme or articulation. The aim of this research was to investigate verb and noun retrieval using a picture-naming task to explore any possible selective noun and/or verb comprehension or retrieval deficits in Greek individuals with anomic aphasia. The results revealed a significant verb/noun dichotomy with verbs significantly more difficult to retrieve than nouns. These findings lend support for the growing body of evidence showing a specific verb impairment in fluent anomic individuals as well as Broca's patients. Given the prevailing view, that anomic patients experience difficulty retrieving the morpho-phonological form of the target word, the results show that specific information of the grammatical category is also important during word form retrieval. LEARNER OUTCOMES: The reader will become familiar with (i) studies investigating grammatical word class breakdown in individuals with aphasia who speak different languages, (ii) the application of the serial model to word production breakdown in aphasia and (iii) the characteristics of verbs and nouns in Greek. It will be concluded that successful verb retrieval for fluent aphasic individuals who speak Greek is dependant on the retrieval of the morpho-phonological information of the target verb.     

The role of semantic complexity in treatment of naming deficits: training semantic categories in fluent aphasia by controlling exemplar typicality.

The effect of typicality of category exemplars on naming was investigated using a single subject experimental design across participants and behaviors in 4 patients with fluent aphasia. Participants received a semantic feature treatment to improve naming of either typical or atypical items within semantic categories, while generalization was tested to untrained items of the category. The order of typicality and category trained was counterbalanced across participants. Results indicated that patients trained on naming of atypical exemplars demonstrated generalization to naming of intermediate and typical items. However, patients trained on typical items demonstrated no generalized naming effect to intermediate or atypical examples. Furthermore, analysis of errors indicated an evolution of errors throughout training, from those with no apparent relationship to the target to primarily semantic and phonemic paraphasias. Performance on standardized language tests also showed changes as a function of treatment. Theoretical and clinical implications regarding the impact of considering semantic complexity on rehabilitation of naming deficits in aphasia are discussed.     

The role of semantic complexity in treatment of naming deficits: training semantic categories in fluent aphasia by controlling exemplar typicality.

The effect of typicality of category exemplars on naming was investigated using a single subject experimental design across participants and behaviors in 4 patients with fluent aphasia. Participants received a semantic feature treatment to improve naming of either typical or atypical items within semantic categories, while generalization was tested to untrained items of the category. The order of typicality and category trained was counterbalanced across participants. Results indicated that patients trained on naming of atypical exemplars demonstrated generalization to naming of intermediate and typical items. However, patients trained on typical items demonstrated no generalized naming effect to intermediate or atypical examples. Furthermore, analysis of errors indicated an evolution of errors throughout training, from those with no apparent relationship to the target to primarily semantic and phonemic paraphasias. Performance on standardized language tests also showed changes as a function of treatment. Theoretical and clinical implications regarding the impact of considering semantic complexity on rehabilitation of naming deficits in aphasia are discussed.     

Evolution of phonemic word fluency performance in post-stroke aphasia

In this longitudinal study, quantitative and qualitative changes in responses of people with aphasia were examined on a phonemic fluency task. Eighteen patients were tested at 3-month intervals on the letters F-A-S while they received comprehensive, intensive treatment from 3 to 12 months post-stroke. They returned for a follow-up evaluation at an average of 10 months post-intervention. Mean group scores improved significantly from beginning to end of treatment, but declined post-intervention. Patients produced a significantly greater number and proportion of modifiers (adjectives and adverbs) between the beginning and end of treatment, with no decline afterwards, implying that they had access to a wider range of grammatical categories over time. Moreover, patients used significantly more phonemic clusters in generating word lists by the end of treatment. These gains may be attributed to the combined effects of time since onset and the linguistic and cognitive stimulation that patients received in therapy. LEARNING OUTCOMES: Readers of this paper should (1) gain a better understanding of verbal fluency performance in the assessment of aphasia, (2) recognize the importance of analyzing qualitative aspects of single word production in aphasia, and (3) contribute to their clinical judgment of long term improvement in aphasia.     

Verbal training to improve explanations of conservation with aphasic adults

Recent research has indicated a need to study the relationship between the language of the adult aphasic and his attempts at cognitive processing. Nine aphasic adults who demonstrated a minimal ability to explain conservation (as defined by Piaget), a cognitive task which they understood, were given verbal model training to improve their explanations of weight and liquid conservation. Each subject was given a pretest, an experimental condition during which explanations for weight conservation only were trained, a control condition during which subjects named pictured common objects, and a posttest. Order of presentation of the experimental and control conditions was varied. As a result of training, a greater number of explanations (quantitative improvement) and a greater number of explanatory concepts (qualitative improvement) were expressed for both the trained and nontrained conservation tasks. It is suggested that the improvement in conservation explanations is the result of "response facilitation effects" as described by Bandura. Furthermore, the improvement in conservation explanations is supportive of Schuell's concept of impaired linguistic retrieval mechanisms in aphasia.     

Comparing fixed- and randomized-interval spaced retrieval in anomia treatment

Spaced retrieval (SR) has recently been modified to target anomia in persons with aphasia (PWA). It relies on a strict management of the inter-stimulus interval (ISI) where the time between stimulus presentations is doubled or halved based on response accuracy. Although SR is successful in treating anomia, it remains to be studied whether the strict ISI management is necessary. The present study compared fixed-interval spaced retrieval (FISR) to randomized-interval spaced retrieval (RISR) in anomia treatment. Using alternating treatments single subject design, three PWA were trained to name 30 target items. Although both treatments were successful, the present data did not reveal one approach as superior even though fewer FISR sessions were needed and more FISR items were maintained on the post-treatment probes. This difference was only minimal suggesting that a less stringent stimulus schedule, as used in RISR, is sufficient for successful treatment outcome. LEARNING OUTCOMES: Readers will be able to describe the spaced retrieval treatment approach using both fixed- and randomized-interval stimulus schedules, as well as applications of this technique in the treatment of anomia in aphasia.     

A comparison of relaxation training and syntax stimulation for chronic nonfluent aphasia

This study examined the effects of relaxation training and syntax stimulation on the spoken language abilities of a 59-year-old male with chronic, nonfluent aphasia of moderate severity. Relaxation training consisted of progressive muscle relaxation (PMR) and guided imagery (GI), whereas the syntax stimulation was a modified version of the Helm Elicited Program for Syntax Stimulation (HELPSS) [(1981). Helm Elicited Language Program for Syntax Stimulation. Austin, TX: Pro-Ed.]. These treatments were applied in the context of a single-subject alternating treatments plus baseline design. Results indicated that although both treatments produced improvements in spoken language, syntax stimulation was associated with larger improvements, particularly in terms of the proportions of grammatical utterances, correct information units (CIUs), and successful utterances produced by the participant. Analysis of treatment order, however, indicated that the participant's best performances of the syntax treatment and of the probe tasks occurred when relaxation training preceded syntax stimulation. These findings suggest that the simplicity and psychological benefits of relaxation training make it a complementary component to traditional linguistic programs for aphasia. Educational objectives: (1) The reader will understand how psychological responses to stress may affect the language processing abilities of adults with aphasia. (2) The reader will be able to describe how relaxation training complements a traditional language treatment approach for remediating spoken language abilities of adults with chronic nonfluent aphasia.     

A review and critical analysis of treatment research related to articulation and phonological disorders.

This article contains a summary of aspects of research designs and strategies found in 63 published reports in which the effectiveness of treatment of articulation or phonological disorders was evaluated. These research reports were published in four nationally refereed journals that contained most of the literature published in the decades of the 1970s and 1980s. A total of 91 items were evaluated in each report by two reviewers working independently, including types of research designs, details about subjects, sampling, and types of independent and dependent variables used by researchers. Comparisons were made within each decade and across both decades to identify strengths and limitations. Some significant differences in research designs and variables under investigation occurred between the decades. A critical analysis was performed, and suggestions for changes are discussed.     

The role of syntactic complexity in treatment of sentence deficits in agrammatic aphasia: the complexity account of treatment efficacy (CATE).

This experiment examined the hypothesis that training production of syntactically complex sentences results in generalization to less complex sentences that have processes in common with treated structures. Using a single subject experimental design, 4 individuals with agrammatic aphasia were trained to comprehend and produce filler-gap sentences with wh-movement, including, from least to most complex, object-extracted who-questions, object clefts, and sentences with object-relative clausal embedding. Two participants received treatment first on the least complex structure (who-questions), and 2 received treatment first on the most complex form (object-relative constructions), while untrained sentences and narrative language samples were tested for generalization. When generalization did not occur across structures, each was successively entered into treatment. Results showed no generalization across sentence types when who-questions were trained; however, as predicted, object-relative training resulted in robust generalization to both object clefts and who-questions. These findings support those derived from previous work, indicating not only that generalization occurs across structures that are linguistically related, but also that generalization is enhanced when the direction of treatment is from more complex to less complex constructions. This latter finding supports the authors' newly coined "complexity account of treatment efficacy" (CATE).