Single-subject Experiments Research Articles

A computational framework for estimating statistical power and planning hypothesis-driven experiments involving one-dimensional biomechanical continua

Statistical power assessment is an important component of hypothesis-driven research but until relatively recently (mid-1990s) no methods were available for assessing power in experiments involving continuum data and in particular those involving one-dimensional (1D) time series. The purpose of this study was to describe how continuum-level power analyses can be used to plan hypothesis-driven biomechanics experiments involving 1D data. In particular, we demonstrate how theory- and pilot-driven 1D effect modeling can be used for sample-size calculations for both single- and multi-subject experiments. For theory-driven power analysis we use the minimum jerk hypothesis and single-subject experiments involving straight-line, planar reaching. For pilot-driven power analysis we use a previously published knee kinematics dataset. Results show that powers on the order of 0.8 can be achieved with relatively small sample sizes, five and ten for within-subject minimum jerk analysis and between-subject knee kinematics, respectively. However, the appropriate sample size depends on a priori justifications of biomechanical meaning and effect size. The main advantage of the proposed technique is that it encourages a priori justification regarding the clinical and/or scientific meaning of particular 1D effects, thereby robustly structuring subsequent experimental inquiry. In short, it shifts focus from a search for significance to a search for non-rejectable hypotheses.

Efficacy of Neurofeedback Training on Reading and Spelling Skills of 8 to 12 Years Old Children With Dyslexia

Introduction: Progress in understanding dyslexia has led to the discovery of abnormal brain waves in the areas related to reading skill. It seems that improving the function of these areas by regulating their waves is helpful for reading process. This study aimed to investigate the efficacy of neurofeedback training (NFT) in improving children’s reading difficulties. Material and Methods: This was a single-subject experiment with A-B-A design. Four dyslexic boys (age range 8-12 years) received twenty 30-minute sessions of NFT three times a week to reduce their theta and delta waves at F7 and increase their beta wave at T3. Their accuracy, speed, reading comprehension, and spelling skill were assessed using Name reading test before, during, and one month after treatment. Data analysis was done by reliable change index, mean percentage improvement, and effect size. Also results were displayed by graphs. Results: The results showed clinically significant improvement regarding the accuracy and comprehension reading as well as spelling after NFT. Reliable changes (P 2.87) refer to significant improvement of these skills. However speed reading increased in two subjects, but the effect size for the first and second participant was negative (Cohen’s d<0). Conclusion: The results suggest that 20 sessions of NFT improves the spelling, accuracy, and comprehension reading. It seems that the increased attention (due to the reduction of theta and delta waves) and performance tuning at T3 was effective in improving these skills. However, increase in speed reading may require more sessions.

Acute and chronic effects of aquatic treadmill training on land treadmill running kinematics: A cross-over and single-subject design approach

ABSTRACTThe aim of this study was to determine if selected kinematic measures (foot strike index [SI], knee contact angle and overstride angle) were different between aquatic treadmill (ATM) and land treadmill (LTM) running, and to determine if these measures were altered during LTM running as a result of 6 weeks of ATM training. Acute effects were tested using 15 competitive distance runners who completed 1 session of running on each treadmill type at 5 different running speeds. Subsequently, three recreational runners completed 6 weeks of ATM training following a single-subject baseline, intervention and withdrawal experiment. Kinematic measures were quantified from digitisation of video. Regardless of speed, SI values during ATM running (61.3 ± 17%) were significantly greater (P = 0.002) than LTM running (42.7 ± 23%). Training on the ATM did not change (pre/post) the SI (26 ± 3.2/27 ± 3.1), knee contact angle (165 ± 0.3/164 ± 0.8) or overstride angle (89 ± 0.4/89 ± 0.1) during LTM running. Although SI values were different between acute ATM and LTM running, 6 weeks of ATM training did not appear to alter LTM running kinematics as evidenced by no change in kinematic values from baseline to post intervention assessments.

Detection of small bleeds in the brain with electrical impedance tomography

In this paper, we describe and assess feasibility of instrumentation and algorithms for detecting bleeding due to hemorrhagic strokes and traumatic brain injury using electrical impedance tomography, a novel biomedical diagnostic modality in which the body is probed noninvasively with generally imperceptible alternating currents applied in patterns to a set of electrodes placed in contact with the skin. We focus on the GENESIS instrument developed by GE Global Research and on the achievability of our goal to detect a bleed in the center of the head with a volume of several ml. Our main topic is compensation for the large changes in voltages that tend to occur when the electrodes are in contact with biological media, specifically either human subjects or with vegetable matter proxies which seem to exhibit the same ‘drift’ phenomenon. We show that these changes in voltages can be modeled by assuming that each electrode is attached to the body via a discrete complex impedance whose value is time-varying and describe how this discrete component value can be estimated and largely compensated-for. We compare this discrete model with changes in contact impedances estimated using the complete electrode model showing that the two models are roughly comparable in their ability to explain the data from a single human subject experiment with electrodes attached to the head. In a simulation study, we demonstrate that it is possible to detect a small bleed in the center of the head even in the case of large changes in electrode impedances, which can be treated as nuisance parameters.

Vietnamese compounds show an anti-frequency effect in visual lexical decision

Although Vietnamese has a long history of linguistic research, as yet no psycholinguistic studies addressing lexical processing in this language have been carried out. This paper is the first to investigate lexical processing in Vietnamese, and this addresses the reading of Vietnamese bi-syllabic compound words. A large single-subject experiment with 20,000 words was complemented by a smaller multiple-subject experiment with 550 words. We report the novel finding of an inhibitory, anti-frequency effect of Vietnamese compounds’ constituents. We show that this anti-frequency effect is predicted by a computational model of lexical processing grounded in naive discrimination learning. We also show that predictors derived from this model provide a much better fit to the observed reaction times than traditional lexical-distributional predictors. Effects of the density of the compound graph, previously observed for English, were replicated for Vietnamese. Furthermore, tone diacritics were found to be important predictors of silent reading, providing further evidence for the role of phonology in reading.

A translational approach to the functional analysis of language in psychotherapy

The functional analysis of verbal behavior has been successful in establishing basic and advanced forms of language in individuals with developmental disabilities. The development of behavioral approaches to psychotherapy, such as the functional-analytic psychotherapy, have advanced the implementation of operant analyses of verbal behavior among typical adults. The field of behavior-analytic approaches to psychotherapy departs from the applied experimental research in behavior analysis in various ways: (a) minimal use of molecular analyses of behavioral processes using single-subject experimentation, (b) confined use of functional analysis and function-driven intervention, and (c) metaphoric use of mainstream behavioral concepts and methods. The breakthroughs brought about by behavioral approaches to psychotherapy may be supplemented by way of translating some of the findings of the applied experimental literature. The present analysis illustrates how behavioral processes demonstrated in the context of experimental research, often with individuals with developmental and intellectual disabilities, may be relevant to psychotherapy with typically-developed adults. This translational approach is discussed with reference to basic language processes: echoics, mands, tacts, and intraverbal dynamics. This approach could prompt programmatic translational research in the field of behavioral psychotherapies.

Structured flexibility and context-sensitive behavioral support for the chronically cranky

A significant number of individuals with brain injury demonstrate behavioral challenges that negatively affect their ability to live successfully in community settings. While there are a number of treatment approaches that have demonstrable effects in well controlled clinical settings, it is very difficult to implement these approaches in natural settings. The goal of this study was to report the results of an investigation of the effects of a multicomponent behavioral intervention on the challenging behavior of an adolescent and young adult with growing behavioral concerns after acquired brain injury (TBI). The participants were an 16 year old adolescent male and a 24 year old female, with escalating behavior problems after severe TBI. Multiple baseline designs were used to document the effects of an intervention package that integrated cognitive and executive function intervention to address severe challenging behaviors in natural settings. The following dependent variables were used to establish the effectiveness of the interventions: frequency and intensity of aggressive behaviors and participation in scheduled activities. The intervention included integrated components of positive behavior supports, cognitive supports and specific executive function scripts. These single subject experiments demonstrated the effectiveness of a multicomponent intervention on the reduction of the frequency of problem behaviors and the increase of pro-social behaviors. These two successful interventions extended the findings of previously published data for the successful treatment of behavioral challenges using a flexible support-oriented intervention that combines behavioral, cognitive, and executive function components.

Plyometric Training

To evaluate the optimal duration and effects of plyometric training on the gross motor abilities of 3 boys with unilateral spastic cerebral palsy (9 years 11 months, 10 years, and 8 years 9 months). This was a multiple-baseline, multiple-probe, single-subject experiment. The intervention followed the National Strength and Conditioning Association's guidelines for youth. The Gross Motor Function Measure 66, 10×5-m sprint, 20-m run, throw ball, broad jump, and vertical jump tests were used to evaluate gross motor abilities, agility, running speed, and power. Improvements were found in upper extremity power, Gross Motor Function Measure 66 scores, and agility. Findings for lower extremity power and running speed were inconsistent. Training duration ranged from 8 to 14 weeks. This study suggests that plyometric training improves gross motor ability, agility, and upper extremity power in boys with unilateral cerebral palsy. Treatment duration should be determined by an individual's capacity, the task, and the outcome measure.

Initiating Functional Vocabulary Learning for Mental Retardation Students with Educational Technology Approach

This study developed functional vocabulary learning system for mental retardation students to assist three moderate ones enrolled in special education classes of vocational schools, and discusses the learning effect of the within and extra fading strategies. And the alternative treatment design of the single subject experiment design was adopted to evaluate the effectiveness of the learning system. The teaching strategy adopted photos of physical goods as cues combined with the fading strategy within a stimulus-control process. After experiment, this study has the preliminary result: Stimulus fading strategies can assist functional vocabulary learning in moderate mental retardation students enrolled in special education classes of vocational schools; learning achievement with the extra fading strategy exceeded that with the within fading strategy.

Considerations in Art E-therapy for Anxiety Disorders

Brief and online versions of cognitive behavioral therapy (CBT)—the favored treatment for severe anxiety disorders—have answered critiques that traditional CBT is too inaccessible and unaffordable. The integration of art into CBT protocols may address further critiques that the concepts of CBT can be too abstract and verbal by adding tangible components. Therefore, art e-therapy may offer a unique treatment option that is more financially and cognitively accessible. In a previously reported single-subject experiment, art e-therapy combined with a CBT protocol resulted in marginally significant decreases in the self-reported general anxiety of a participant with generalized anxiety disorder. Aspects of the case relating specifically to art e-therapy are discussed, including considerations for art e-therapy best practice. Taking the reported case and related literature into account, potential costs and benefits of using this treatment modality are discussed. Although art e-therapy can involve greater risks to confidentiality and reduced clarity of the art making process than in-person art therapy, it resulted in greater participant independence and convenience in this case.

Children with autism social engagement in interaction with Nao, an imitative robot

This paper presents a series of 4 single subject experiments aimed to investigate whether children with autism show more social engagement when interacting with the Nao robot, compared to a human partner in a motor imitation task. The Nao robot imitates gross arm movements of the child in real-time. Different behavioral criteria (i.e. eye gaze, gaze shifting, free initiations and prompted initiations of arm movements, and smile/laughter) were analyzed based on the video data of the interaction. The results are mixed and suggest a high variability in reactions to the Nao robot. The results are as follows: For Child2 and Child3, the results indicate no effect of the Nao robot in any of the target variables. Child1 and Child4 showed more eye gaze and smile/laughter in the interaction with the Nao robot compared to the human partner and Child1 showed a higher frequency of motor initiations in the interaction with the Nao robot compared to the baselines, but not with respect to the human-interaction. The robot proved to be a better facilitator of shared attention only for Child1. Keywords: human-robot interaction; assistive robotics; autism

Quality Appraisal of Single-Subject Experimental Designs: An Overview and Comparison of Different Appraisal Tools

Critical appraisal of the research literature is an essential step in informing and implementing evidence-based practice. Quality appraisal tools that assess the methodological quality of experimental studies provide a means to identify the most rigorous research suitable for evidence-based decision-making. In single-subject experimental research, quality appraisal is still in its infancy. Seven different quality appraisal tools were identified and compared with respect to their compliance with current standards for conducting single-subject experiments as well as their performance in evaluating research reports. Considerable variability was noted relative to the construction and content of the tools, which consequently led to variability in their evaluation results. Few tools provided empirical support for the validity of item construction and reliability of use. The Evaluative Method , the Certainty Framework , the What Works Clearinghouse Standards , and the Evidence in Augmentative and Alternative Communication Scales were identified as the more suitable instruments currently available for the critical appraisal of single-subject experimental designs, noting their different strengths and limitations. In the absence of a "gold standard critical appraisal tool," applied researchers and practitioners need to proceed with caution when interpreting evaluation results obtained from the existing tools, keeping their context and intent in mind.

Structured Flexibility

This study investigated the effects of a cognitive-behavioral intervention on the escalating behavior problems observed in 2 children with severe traumatic brain injury. Multiple baseline designs were used to document the effects of an intervention package that integrated cognitive and executive function interventions to address severe challenging behaviors in public school settings. The results suggested that the intervention reduced the frequency and intensity of challenging behaviors and increased the quantity of work completed. These 2 successful single-subject experiments expand the findings of previous studies on the use of a support-oriented intervention that uses context-sensitive, flexible cognitive/behavioral scripts combined with positive behavior interventions and supports to reduce challenging behaviors.

Effectiveness of the Picture Exchange Communication System (PECS) on Communication and Speech for Children With Autism Spectrum Disorders: A Meta-Analysis

The Picture Exchange Communication System (PECS) is a popular communication-training program for young children with autism spectrum disorders (ASD). This meta-analysis reviews the current empirical evidence for PECS in affecting communication and speech outcomes for children with ASD. A systematic review of the literature on PECS written between 1994 and June 2009 was conducted. Quality of scientific rigor was assessed and used as an inclusion criterion in computation of effect sizes. Effect sizes were aggregated separately for single-subject and group studies for communication and speech outcomes. Eight single-subject experiments (18 participants) and 3 group studies (95 PECS participants, 65 in other intervention/control) were included. Results indicated that PECS is a promising but not yet established evidence-based intervention for facilitating communication in children with ASD ages 1-11 years. Small to moderate gains in communication were demonstrated following training. Gains in speech were small to negative. This meta-analysis synthesizes gains in communication and relative lack of gains made in speech across the PECS literature for children with ASD. Concerns about maintenance and generalization are identified. Emerging evidence of potential preintervention child characteristics is discussed. Phase IV was identified as a possibly influential program characteristic for speech outcomes.

Random Subspace Ensembles for fMRI Classification

Classification of brain images obtained through functional magnetic resonance imaging (fMRI) poses a serious challenge to pattern recognition and machine learning due to the extremely large feature-to-instance ratio. This calls for revision and adaptation of the current state-of-the-art classification methods. We investigate the suitability of the random subspace (RS) ensemble method for fMRI classification. RS samples from the original feature set and builds one (base) classifier on each subset. The ensemble assigns a class label by either majority voting or averaging of output probabilities. Looking for guidelines for setting the two parameters of the method-ensemble size and feature sample size-we introduce three criteria calculated through these parameters: usability of the selected feature sets, coverage of the set of "important" features, and feature set diversity. Optimized together, these criteria work toward producing accurate and diverse individual classifiers. RS was tested on three fMRI datasets from single-subject experiments: the Haxby data (Haxby, 2001.) and two datasets collected in-house. We found that RS with support vector machines (SVM) as the base classifier outperformed single classifiers as well as some of the most widely used classifier ensembles such as bagging, AdaBoost, random forest, and rotation forest. The closest rivals were the single SVM and bagging of SVM classifiers. We use kappa-error diagrams to understand the success of RS.

Classifier ensembles for fMRI data analysis: an experiment

Functional magnetic resonance imaging (fMRI) is becoming a forefront brain-computer interface tool. To decipher brain patterns, fast, accurate and reliable classifier methods are needed. The support vector machine (SVM) classifier has been traditionally used. Here we argue that state-of-the-art methods from pattern recognition and machine learning, such as classifier ensembles, offer more accurate classification. This study compares 18 classification methods on a publicly available real data set due to Haxby et al. [Science 293 (2001) 2425-2430]. The data comes from a single-subject experiment, organized in 10 runs where eight classes of stimuli were presented in each run. The comparisons were carried out on voxel subsets of different sizes, selected through seven popular voxel selection methods. We found that, while SVM was robust, accurate and scalable, some classifier ensemble methods demonstrated significantly better performance. The best classifiers were found to be the random subspace ensemble of SVM classifiers, rotation forest and ensembles with random linear and random spherical oracle.

What can clinical behaviour analysis contribute to nidotherapy?

AbstractNidotherapy is an approach that involves the assessment and modification of situational or interpersonal aspects. It is used to reduce the impact of severe mental disorder when previous therapies have failed and suggests that its methods result in improved social functioning. We describe nidotherapy as a novel intervention, and to enhance understanding, compare and contrast nidotherapy with clinical behaviour analysis. To facilitate establishing an evidence base, our recommendations include: clarification of the theory underlying nidotherapy; collaboration with clinical behaviour analysts to explore the role of situational and interpersonal changes within the theoretical system; design of single‐subject experiments to gather data pertaining to individuals; consideration of Functional Analytic Psychotherapy to examine the therapeutic bond; a definition of the repertoires and competencies of nidotherapists to guarantee supervision; and long‐term follow‐up to rule out unintended effects of environmental changes. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Expanding Literacy for Learners with Intellectual Disabilities: The Role of Supported eText

A series of single-subject experiments were conducted to evaluate the effects of presentational, translational, illustrative, instructional, and summarizing supports on the reading and listening comprehension of students with moderate intellectual disabilities. The specific eText supports under investigation included digitized voice and text-to-speech, text highlighting, video summaries, text-linked photographs, and graphic organizers. Two eText supports were found to be effective in supporting text comprehension for this population: reading the text out loud (using either recorded voice or text-to-speech), and graphic organizers. The findings also revealed the importance of providing explicit instruction in how to use eText supports. The article summarizes six studies and discusses the implications of the results for students with moderate intellectual disabilities, their teachers, and their parents.

ShopTalk: Independent Blind Shopping Through Verbal Route Directions and Barcode Scans

Independent shopping in modern grocery stores that carry thousands of products is a great challenge for people with visual impairments. ShopTalk is a proof-of-concept wearable system designed to assist visually impaired shoppers with finding shelved products in grocery stores. Using synthetic verbal route directions and descriptions of the store lay- out, ShopTalk leverages the everyday orientation and mobility skills of independent visually impaired travelers to direct them to aisles with target products. Inside aisles, an off-the-shelf barcode scanner is used in conjunction with a software data structure, called a barcode connectivity matrix, to locate target product on shelves. Two experiments were performed at a real world supermarket. A successful earlier single-subject experiment is summarized and a new experiment involving ten visually impaired participants is presented. In both experiments, ShopTalk was successfully used to guide visually im- paired shoppers to multiple products located in aisles on shelves. ShopTalk is a feasible system for guiding visually im- paired shoppers who are skilled, independent travelers. Its design does not require any hardware instrumentation of the store and leads to low installation and maintenance costs.

An Initial Comparison Of Collaborative And Expert-Driven Consultation On Treatment Integrity

Although over 15 years have passed since Witt (1990) noted that no empirical evidence exists to support the contention that a collaborative approach to consultation leads to more positive outcomes than a hierarchical or expert driven approach, this issue generally remains unaddressed (Schulte & Osborne, 2003). While the literature documenting the benefits of consultation has continued to grow, a true head-to-head comparison has not been conducted. The purpose of the present study was to directly address Witt's call by empirically examining the impact of two consultation styles on a critical variable, practitioner treatment integrity. It was hypothesized that the involvement of practitioners in all aspects of intervention design would increase their level of treatment integrity. Two single-subject experiments using multiple baseline across subjects designs were used to examine the difference in level of treatment integrity for an imported, expert-driven intervention and a partnership-designed intervention. The first experiment was divided into three phases: (a) Phase I, Expert-driven Model; (b) Phase II, Treatment Integrity Intervention; and (c) Phase III, Partnership Model. The second experiment presented the three phases in reverse order to address the possibility of presentation effects: (a) Phase I, Partnership Model; (b) Phase II, Expert-driven Model; and (c) Phase III, Treatment Integrity Intervention. In general, the five participants who completed the three phases of the experiments demonstrated higher levels of treatment integrity during the partnership phase. Overall, the results suggest that engaging with consultees in a collaborative approach may increase the level of integrity with which the intervention is applied.