Purpose: Adults with stuttering (AWS) commonly demonstrate verbal avoidance behaviours as a result of speech-related anxiety. This can result in an experience of ‘communication restriction’. By nature, verbal avoidance and communication restriction are difficult to evaluate objectively, and existing evidence consists primarily of self-report data from qualitative interviews. However, recent preliminary evidence indicates the potential utility of systemic functional linguistics (SFL; Halliday, 1985) to this area of research. The SFL framework provides quantitative analyses for the objective examination of language use in sociolinguistic contexts. Recent data also suggest that the confrontation naming paradigm may be a second possible means for quantitatively evaluating aspects of functional linguistic behaviour in AWS. The purpose of the present study was to identify specific patterns of conversational language and confrontation naming behaviour in AWS using an objective methodology, and to explore these behaviours within the context of stuttering intervention and with reference to the experience of communication restriction.

Method: Twenty AWS (14 males, 6 females) and 20 matched controls (AWNS), aged between 16 and 56 years, were recruited for this study. All participants were native speakers of English with no cognitive, language, motor speech, or hearing impairment (with the exception of stuttering in AWS). All participants completed: (a) self-rating scales of general and communication-related attitudes and anxiety; (b) the UC Picture ID (O’Beirne, 2011) picture naming task, designed to objectively evaluate verbal avoidance behaviour; and (c) 10 minutes of spontaneous conversation with an examiner, loosely structured around a range of set topics. For the AWS participants, these procedures were completed pre- and post-attendance at either the Naturalness Intensive Programme in Christchurch, New Zealand (NZ), or the Intensive Stuttering Clinic (Blomgren, 2009) in Salt Lake City, USA (US). All conversational samples were analysed using both conventional and SFL-based analyses. Specifically, the quantity and complexity of verbal output, as well as the frequency of use of transitivity, modality, appraisal, and thematic resources, were examined.

To identify group differences on all measures between AWNS and AWS at both pre- and post-treatment, two-tailed independent samples t-tests and Mann-Whitney U-tests were conducted. To compare the performance of AWS between pre- and post-treatment, two-tailed paired t-tests and Wilcoxon matched pairs signed ranks tests were used. Group comparisons were conducted for the full participant group, as well as separately for the NZ and US subgroups. Pearson correlation matrices were also constructed, to identify linear relationships between measures. Correlations between conventional and SFL analyses of linguistic behaviour were of particular interest.

Results: Group differences for each subgroup were generally consistent with those for the full participant group. (a) AWS demonstrated higher social anxiety than AWNS at pre-treatment, but self-reported anxiety levels and stuttering impact decreased following treatment. (b) No differences were found across comparisons for confrontation naming performance on the UC Picture ID task. (c) In conversation, AWS produced consistently less language than AWNS, and produced less complex language than AWNS at pre-treatment, as shown by conventional and SFL indices. Specific SFL measures revealed fewer politeness-marking modal operators, more frequent comment adjuncts, and reduced expression of appraisal in the spontaneous language of AWS. Improvements in most of these areas were seen following treatment. The results of the correlational analyses showed that self-report scale outcomes were not linearly correlated to actual performance on any linguistic measures. However, positive correlations were observed between basic linguistic indices (i.e., language productivity and complexity) from the conventional and SFL approaches. An interesting negative correlation between language productivity and frequency of use of comment adjuncts was also seen.

Conclusions: The current study extends available preliminary evidence on language use in AWS. Linguistic patterns identified in the conversational language of AWS suggest a reduced openness to interpersonal engagement within communication exchanges, which may restrict the experience of such exchanges. The data indicate that conventional and SFL analyses are interchangeable at a basic level, but also exemplify the unique utility of the SFL framework for examining specific aspects of language functionality within social context. Although AWS and AWNS were not found to differ in performance on the UC Picture ID task, the observations provide insight into the conditions under which verbal avoidance behaviours may be prone to occurring. Finally, the lack of straightforward correlations between self-reported anxiety and avoidance on the one hand, and various linguistic-behavioural indicators on the other, highlights the importance of a multidimensional, holistic approach to clinical stuttering evaluation.