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Biomedical subjects

Mark Onslow

Publications and source records attributed to Mark Onslow.

30 records · Page 2Linked to original sources
PubMed2002

Statistical power in stuttering research: a tutorial.

The capacity to make reliable inductive statements about populations is critical for the advancement of scientific knowledge. An important contribution to that advancement of knowledge is determining that effects are either present or not present in populations. Statistical power is an important methodological qualification for any research that presents statistical results, and particularly so for research that presents null results. In this paper we describe the statistical concept of power, outline parameters of research that influence it, and demonstrate how it is calculated. With reference to selected published research, attention is drawn to the problems associated with a body of underpowered research, one being that population effects may go undetected. One way to prevent this problem is to calculate power a priori in planning research and include confidence intervals when presenting the results of research. However, it is difficult, if not impossible in many cases, to obtain high participant numbers for communication disorders of low prevalence such as stuttering. With this in mind, the paper concludes with an attempt to open discussion about ways to redress the problems associated with statistical power.

Humans↗
PubMedDate not supplied

Speech timing in children after the Lidcombe Program of early stuttering intervention.

It is known that operant treatments can control stuttering in children. However, at present it is unknown why such treatments are effective. Changes in the usual way of speaking are frequently observed after behavioural treatments for adults who stutter, and it is possible that operant treatments for children also invoke such changes. To explore this idea, selected acoustic measures of speech timing were made in eight preschool children before and after receiving the Lidcombe Program, which is an operant treatment for stuttering. No systematic changes were detected after treatment. Considering this finding and a previous report, there is no evidence to suggest that the reductions in stuttering that occur with this treatment are related to systematic changes in speech timing or curtailment of language function.

Child, Preschool↗
PubMedDate not supplied

A preliminary investigation of the impact of stuttering on language use.

This paper reflects on the application of Systemic Functional Linguistics (SFL) to the field of stuttering. It is argued that the SFL theory may offer insight into the impact that stuttering has on language use. Two case studies are presented to illustrate the application of SFL theory. The two SFL analyses found to be of most use in this pilot study were the analysis of how language is modulated in response to interpersonal aspects of communication (modality) and the analysis of how information is foregrounded (theme). The implications of applying the SFL model to consideration of the utilisation of language resources in people who stutter are discussed.

Adult↗
PubMedDate not supplied

Treatment of chronic stuttering: outcomes from a student training clinic.

BACKGROUND: It has been suggested that one way to increase speech pathologists' confidence in working with people who stutter is to provide them with relevant and stimulating clinical experiences during their professional preparation. This paper describes a treatment programme for adults who stutter that is conducted by speech pathology students, under supervision, in an Australian university setting. The aim of the research presented here was to establish speech outcomes for this programme, and to determine whether the programme meets benchmarks set by reports of similar programmes, in addition to providing mentorship for student clinicians. METHODS & PROCEDURE: Participants were 78 adults who were treated in one of five consecutive treatment programmes during a 3-year period. The treatment was a traditional intensive speech restructuring treatment known as Smooth Speech, conducted over a 5-day period. Speech assessments were conducted 1 week and 1 day before the start of the treatment programme. Post-treatment assessments were conducted immediately following the intensive component of the programme, and 3 months, 12 months and 3.5-5 years post-treatment. The student clinic treatment model in this report produced objective speech data for more subjects in one outcome study than has ever been reported before. Data for 87% (68/78) of participants were available at 3.5-5-year follow-up. Results showed that outcomes for stuttering, speech naturalness, and client self-reports were all comparable with existing reports of similar programmes. The present results were attained with a student/supervisor ratio of around 8:1. CONCLUSIONS: We conclude that a clinician-supervised student clinic has the potential to supply services for those with chronic stuttering, as well as providing effective clinical education for student clinicians during their professional preparation. The student clinic treatment model produced varied, objective speech data for more subjects than has ever been reported before in one study. The present findings also replicated a previous finding that stuttering was more severe within the clinic than in speech samples collected in everyday speaking environments.

Adolescent↗
PubMedDate not supplied

Psychological impact of the Lidcombe Program of early stuttering intervention.

The Lidcombe Program is an operant treatment for stuttering in preschool children for which favourable outcome and social validity data have been published. The treatment involves parental praise for stutter-free speech in children's everyday speaking environments, and occasional correction of stuttered speech. Theoretical perspectives on the origins of stuttering have prompted suggestions that the Lidcombe Program may have an adverse psychological impact on children. The present preliminary investigation sought to identify any evidence of such a systematic, pernicious trend, which might justify statistically powerful investigations of the issue with large subject numbers. Subjects were eight preschool children who were successfully treated with the Lidcombe Program. The Child Behavior Checklist (CBCL) detected any post-treatment behavioural markers of changes in children such as anxiety, aggression, withdrawal or depression. The Attachment Q-Set (AQS) measured any changes in the quality of the attachment relationship between child and mother over the course of treatment. These case studies revealed no evidence of a systematic trend in either. In fact, CBCL data suggested improvements in the children after treatment. It is concluded that there is no reason to doubt that the Lidcombe Program is a safe treatment.

Child Behavior↗
PubMedDate not supplied

Predicting treatment time with the Lidcombe Program: replication and meta-analysis.

BACKGROUND: The benefits of treating stuttering close to onset have become obvious in recent years, and the Lidcombe Program has emerged as an effective and safe treatment method for children in their preschool years. The benefits of implementing the programme with young children, however, need to be weighed against the knowledge that many children recover from stuttering without treatment. In light of this, speech-language therapists need to know how long treatment is likely to take and whether treatment time can be predicted. In particular, they need to know if adopting a 'watchful waiting' approach--to see if natural recovery occurs--jeopardizes responsiveness to treatment. A recent Australian study of 250 preschool-age children found that stuttering rate was the only significant predictor of treatment time with the Lidcombe Program. In other words, children whose stuttering was more severe took longer to pass through the programme. There were other trends in the data but they did not reach significance. AIMS: The present study, conducted independently in the UK, was designed to replicate the Australian study. Direct replication enabled pooling of the data from the two studies in a meta-analysis. METHODS & PROCEDURES: The study included 66 children who began treatment before 6 years of age. They were treated with the Lidcombe Program at a specialist stuttering clinic in Norwich. Logistic regression analyses were conducted on the data. The data from both the British and Australian cohorts were pooled in a meta-analysis. OUTCOMES & RESULTS: Results indicated that Stage 1 of the Lidcombe Program was completed in a median of 11 clinic visits, which is in line with the findings of the Australian study. Stuttering rate at first clinic visit was again found to be a significant predictor of treatment time. The remaining data trends were similar to those in the Australian data. In the meta-analysis, stuttering rate was once more found to be a predictor of treatment time. Of particular interest, however, was that the increased power provided by the meta-analysis identified an additional predictor, namely onset-to-treatment interval. Contrary to what is known about the responsiveness of children to the Starkweather and Gottwald treatment, and contrary to what might be expected given what we know about natural recovery, children who had been stuttering for more than 12 months took less time to progress through the programme than children who had been stuttering for less than 12 months. CONCLUSIONS: These findings indicate that delaying intervention with the Lidcombe Program for 1 year after onset, within the preschool years, is unlikely to jeopardize responsiveness to treatment. The clinical implications of these findings are discussed.

Age Factors↗
PubMedDate not supplied

Protection from harm: the experience of adults after therapy with prolonged-speech.

BACKGROUND: It is well documented that adults can control stuttering if they use certain novel speech patterns referred to generically as prolonged-speech (PS). These speech patterns were refined in the 1960s and developed into behavioural treatment programmes. The bulk of available PS treatment research has focused on speech parameters thought to reflect favourable treatment outcome. Considering this, and that post-treatment relapse is known to be common, clinicians and researchers could be usefully informed by knowledge about the experiences of those who receive these treatments. Subsequently, they could use such information in attempts to control stuttering in their clients. Yet, at present, systematic research on this topic is scant. AIMS: The continued development of PS treatments could be usefully informed by research into the experiences of those who use PS to control stuttering. Hence, that is the topic of the present report. METHODS & PROCEDURES: The method used was phenomenology. Participants were a purposive sample of 10 people who had received PS treatment. During a 2-year period, a collaborative approach to the study of the topic was developed between the participants and interviewer. Interviews were from 1.5 to 2 hours, and a total of 34 interviews and discussions were undertaken with participants. Transcripts of these were used to generate text from which themes were identified using line-by-line, holistic and selective approaches. OUTCOMES & RESULTS: The main findings were that even after therapy with PS there is a continued risk of stuttering occurring, and although adults have the novel experience of controlling stuttering, they also continue to experience feeling different from those who do not stutter, which may be exacerbated after therapy. Given the negative consequences associated with stuttering and feeling different, the essence of the experience after therapy with PS is that adults use their own resources to integrate behavioural skills with existing experiences in order to protect themselves from the harm of stuttering as best they can. PS changes speech, but not the dynamic and often unpredictable communication situations of everyday life. Hence, the maximum benefits of PS are attained when clients use a strategic approach to control stuttered speech and daily communication. CONCLUSIONS: These findings are consistent with the results of existing outcome research as well as with other current research from the present group. Their implications are discussed in relation to the structure of PS treatments as well as in relation to future PS outcome research. The clinical implications of these findings are discussed in terms of informing prospective clients of the experiential consequences of PS, selecting clients who might benefit from PS and in terms of assisting clients to achieve optimal benefits from PS.

Adult↗
PubMedDate not supplied

Dismantling the Lidcombe Program of early stuttering intervention: verbal contingencies for stuttering and clinical measurement.

BACKGROUND: Data have accumulated to show that the Lidcombe Program of early stuttering intervention is a safe treatment with positive outcomes for preschoolers who stutter, and a randomized controlled trial is under way at the time of writing. Program components have not been investigated experimentally so the functionality of each component is unknown. AIMS: The aim of this preliminary study was to establish the viability of a programme of research that would assess the clinical value of two program components. These components were parental verbal contingencies for stuttering and severity ratings. METHODS & PROCEDURES: In the present preliminary experiment, 38 preschool children were randomized to an experiment involving a 4-week 'dose' of treatment followed by 4 weeks without treatment. The dependent variable was the percentage of syllables stuttered (%SS) obtained from the mean %SS score from recordings on three recording occasions. OUTCOMES & RESULTS: Some preliminary indications were found that parental verbal contingencies for stuttering contributed to treatment outcomes. No preliminary evidence was found for the contribution of parent severity ratings to treatment outcomes. CONCLUSIONS: It was concluded that a robust, statistical demonstration of these result would be desirable, but effect size estimates from the present data show that access to more than 650 families of stuttering preschool children would be required for such a study. Such a project would be beyond the resources of any one research group to complete in a timely manner, and a method to address this problem is proposed.

Behavior Therapy↗
PubMedDate not supplied

Effects of self-modelling on stuttering.

BACKGROUND: The paper reports on a laboratory investigation of the effects of self-modelling on stuttering rate in adolescents and adults. Self-modelling refers to a therapeutic or training method, usually involving videotape, that uses exposure to oneself performing selected error-free behaviours as the conduit for promoting behaviour change. AIMS: To investigate self-modelling in single-subject experiments to determine whether any reductions in stuttering could be directly attributable to watching self-modelling videotapes and to ascertain whether instruction to focus attention on the target behaviour, namely stutter-free speech, was necessary for experimental effects. METHODS & PROCEDURES: A single-subject withdrawal design was employed with two adult men and an adolescent boy. Speaking sessions during all phases of the study were of 3-min duration. During the B Phase, subjects watched one of their self-modelling videotapes, which had been edited to remove all stuttered speech, before each speaking session. In the B + C Phases, subjects continued to watch the self-modelling videotapes before each speaking session and, in addition, were instructed to attempt to speak during the session as they had spoken on the videotape. OUTCOMES & RESULTS: Stuttering reduced under self-modelling conditions for one of the three subjects. This effect was observed during the B + C Phases, which included instruction to attend to the target behaviour. CONCLUSIONS: The study provides laboratory evidence that self-modelling can ameliorate stuttering. The clinical implications of this finding are that treatments for adults may well benefit from the inclusion of self-modelling procedures, and self-modelling procedures may form a part of relapse prevention and management strategies.

Adolescent↗
PubMedDate not supplied

Connecting stuttering management and measurement: V. Deduction and induction in the development of stuttering treatment outcome measures and stuttering treatments.

BACKGROUND: The development of evidence-based practice, which is increasingly popular in stuttering treatment, is closely linked to the development of outcome measures. AIMS: Two approaches to the development of stuttering treatment outcome measures are outlined. The first is the deductive, top-down approach, where the development of specific outcome measures is guided by a priori general conceptualizations of the nature of the disorder. A competing approach to the development of stuttering treatment outcome measures is outlined. This is the inductive, or bottom up approach. This approach uses Baer's (1988, 1990) notion of specific complaints of clients as the starting point to develop inductive statements for use as general guidance for developing treatment outcome measures. MAIN CONTRIBUTION: It is argued that the deductive approach to development of outcome measures has limitations. It is overly prescriptive, generating numerous and increasingly complex outcome measures that are potentially confusing for clinicians. Further, it is arbitrary and fragile, being linked to conceptualizations and theories about stuttering, which, by necessity, are limited themselves. Further, the development of numerous outcome measures is not compatible with the conduct of randomized controlled trials, which allow a maximum of two primary outcome measures. In contrast, the inductive approach to the development of outcome measures has in its favour that it is empirically driven rather than arbitrary, and that it facilitates a yoking of the development of clinical outcomes and the clinical methods to attain those outcomes. The approach is unlikely to lead to the development of fruitless treatment methods. Further, the approach is parsimonious to the extent that it is likely to produce few guiding generalities for treatment outcome assessment -- perhaps as few as two in the case of adults and one in the case of preschoolers. This is well suited to the use of the randomized controlled trial as a source of evidence for treatment efficacy. CONCLUSIONS: One inductive statement that can be used to guide the development of outcome measures is that the ill effects of stuttered speech could be troubling for those who seek clinical help. The other is that those who seek clinical help are likely to experience speech-related anxiety. Together, these sources of information provide sound guidance for the development of outcome measures relating to stuttered speech and speech-related anxiety, and guidance for the development of treatments to offset those ill effects of the condition. Until another outcome measure can be derived from inductive processes, those treatment developments should serve all the needs of those who stutter and the clinicians who provide those needs.

Anxiety↗
PubMedDate not supplied

Connecting stuttering management and measurement: IV. Predictors of outcome for a behavioural treatment for stuttering.

BACKGROUND: Clinical trials have shown that behavioural treatments based on variants of prolonged-speech (PS) are best practice for reducing the stuttering rate in adults. However, while stuttering is significantly reduced or eliminated for most adults in the short-term with such treatment, relapse in the longer-term is common. Consequently, there has been interest in attempting to establish variables that predict responsiveness to PS-based treatments. Identifying such variables would enable risk prediction and also contribute to the tailoring of treatments to suit individuals who are less likely to benefit in the long-term from the conventional PS-based treatments. Variables that have been investigated to date are the stuttering severity, the attitude to communication and the locus of control. AIMS: The present study revisited this issue with methodological improvements. METHODS AND PROCEDURES: Prospective, continuous measures of outcome several years after treatment, and well-powered, least-squares multivariate regression, with backwards elimination, were used to determine the best model to predict short- and long-term outcomes of a PS-based treatment. Other predictor variables were also included. The stuttering rates of 78 participants were measured immediately after the intensive stage of treatment, and during a surprise telephone call 3.5-5 years after treatment. OUTCOMES AND RESULTS: Attitude to communication and locus of control were separate constructs to stuttering rate. While the stuttering rate predicted outcome, neither of the two non-behavioural variables predicted outcome in either the short- or the long-term. CONCLUSIONS: The most significant finding is that the non-behavioural variables of attitude to communication and locus of control did not predict treatment outcomes. This is contrary to the findings of most previous studies.

Adolescent↗