Influence of stuttering variation on talker group classification in preschool children: Preliminary findings

Abstract

The purpose of this study was to investigate whether variations in disfluencies of young children who do (CWS) and do not stutter (CWNS) significantly change their talker group classification or diagnosis from stutterer to nonstutterer, and vice versa. Participants consisted of seventeen 3- to 5-year-old CWS and nine 3- to 5-year-old CWNS, with no statistically significant between-group difference in chronological age (CWS: M = 45.53 months, S.D. = 8.32; CWNS: M = 47.67 months, S.D. = 6.69). All participants had speech, language, and hearing development within normal limits, with the exception of stuttering for CWS. Both talker groups participated in a series of speaking samples that varied by: (a) conversational partner [parent and clinician], (b) location [home and clinic], and (c) context [conversation and narrative]. The primary dependent measures for this study were the number of stuttering-like disfluencies (SLD) per total number of spoken words [%SLD] and the ratio of SLD to total disfluencies (TD) [SLD/TD]. The results indicated that significant variability of stuttering did not exist as a result of conversational partner or location. Changes in context, however, did impact the CWS, who demonstrated higher SLD/TD in the conversation sample versus a narrative sample. Consistent with hypotheses, CWS and CWNS were accurately identified as stutterers and nonstutterers, respectively, regardless of changes to conversational partner, location or context for the overall participant sample. Present findings were taken to suggest that during assessment, variations in stuttering frequency resulting from changes in conversational partner, location or context do not significantly influence the diagnosis of stuttering, especially for children not on the talker group classification borderline between CWS and CWNS.

Learning outcomes: Readers will be able to: (1) Describe the role of variability in stuttering frequency for young children who stutter; (2) Identify three fundamental measurements of the frequency of stuttering-like and nonstuttering-like disfluencies; (3) Describe the effects of stuttering variation on talker group classification of stuttering or nonstuttering.

Introduction

Variability is considered to be one hallmark of childhood stuttering (e.g., Ingham & Riley, 1998; Johnson, 1961, Meyers, 1986; Sawyer & Yairi, 2006; Yaruss, 1997). In essence, a child who stutters (CWS) may demonstrate differences in frequency and/or severity of stuttering across various situations, over a given period of time (Guitar, 1998) or as a result of changes in speaking or articulatory rate (see Hall, Amir, & Yairi, 1999, for a review of speaking rate in CWS). Although the exact reason(s) for the variability of childhood stuttering is still unknown, investigators have assessed several variables in attempts to determine those communicative contexts, events, etc. associated with such variability.

Specifically, researchers have investigated how stuttering varies or changes in relation to conversational partner (e.g., Martin, Haroldson, & Kuhl, 1972; Yaruss, 1997), conversational location (e.g., Onslow, Costa, & Rue, 1990; Silverman, 1971, Silverman and Silverman, 1971), as well as conversational context (e.g., Johnson, 1961, Yaruss, 1997). Central to all of these investigations is the notion that stuttering is most apparent when the child is conversing with a conversational partner, a situation that most closely emulates the child's real-life speaking experiences (Ingham & Riley, 1998) and less apparent during a narrative or story-telling task (Yaruss, 1997). Thus, bi-directional communication, between a child who stutters and his or her conversational partner, typically a mother or father, in a naturalistic environment (i.e., home) is considered to be one key prerequisite for childhood stuttering to manifest itself (Martin, Kuhl, & Haroldson, 1972). In contrast, CWS are less likely to exhibit more atypical disfluencies during a monologue-type task (i.e., a narrative or story telling task) (Yaruss, 1997) when compared to dialogue-type tasks (i.e., conversational task).

Although less well studied than conversational discourse, stuttering variability within narrative tasks (i.e., story-retelling and story generation) has also been explored (e.g., Trautman, Healey, Brown, Brown, & Jermano, 1999). Specifically, findings indicated that the percentage of stuttering was significantly higher during a story-retelling task in comparison to a story generation task. It is important to note that empirical studies of narrative abilities (e.g., Scott, Healey, & Norris, 1995; Weiss & Zebrowski, 1994) and stuttering variability (Trautman et al., 1999) in children who stutter have typically involved school-aged children with limited discussion regarding preschool-age children (e.g., Yaruss, 1997). Thus, if stuttering frequency of school-age children varies as a result of narrative task elicitation, one might expect to observe the same with preschool children who stutter. This assumption, however, awaits empirical verification.¹

Interestingly, in most of the above studies there is minimal discussion of whether differences or variability of childhood stuttering actually have a significant impact in terms of the child being diagnosed or classified as a stutterer. For example, would a child conversing with the same conversational partner, in the child's home versus a typical clinical setting, exhibit enough variability of stuttering to result in a different diagnosis of stuttering in the home versus clinic? In essence, would variability in stuttering frequency, from one situation or conversational partner to another be sufficient to lead a clinician or researcher to classify a child a stutterer one time but a normally fluent speaker another?

Realistically, not all clinicians have access to other communication partners (i.e., the parent), locations (i.e., home), or contexts (i.e., narrative). This fact would seem to suggest that obtaining multiple sampling of partners, location and context is the ideal or recommended protocol rather than the real protocol that most clinicians must perforce typically employ. It seems reasonable, therefore, to explore whether this relatively common practice – of using less than multiple samples of various communication partners, locations and contexts – significantly impacts a clinician's ability to determine talker group classification.

We hasten to note, however, that none of the above suggests that variability in stuttering frequency does not occur with changes in partners, situations or context. Instead, what it does suggest is that such variability may not make a significant difference when determining whether a child should be classified or diagnosed as someone who stutters. Indeed, we are suggesting that the importance of stuttering variability should be considered in reference to how it may or may not impact a variety of diagnostic, treatment or research decisions like talker group classification. These are, of course, all empirical issues in wait of objective examination.

It is apparent, upon reflection, that the number of permutations of different conversations, conversational partners and conversational situations is beyond the scope of any one empirical study. Nevertheless, some reasonable beginning can and should be initiated in attempts to determine whether variation, at both groups as well as individual levels, is sufficient to impact diagnostic decisions. It would seem that if such variability was of sufficient magnitude, most preschool-age CWS would frequently be diagnosed as a person who stutters in one situation but not in another. Although not an unreasonable conjecture, such possibilities do not appear to be supported, one way or the other, based on clinical experience as well as empirical data.

Again, the present writers are not questioning whether variability exists among CWS. Variability in stuttering frequency is apparent to anyone who treats and studies childhood stuttering. Indeed, variability in stuttering is one of the main reasons prudent clinicians attempt to characterize the degree (as well as possible sources) of variability of stuttering for the child they are treating (Ingham & Riley, 1998). This window of variability serves as a referent or benchmark against which to assess whether the child's therapeutic intervention is more or less effective. Those are sound practices that we do not question. What we do question, however, is whether variability of stuttering frequency is sufficient to “cross” diagnostic boundaries for most children who stutter.

We speculate that for children who stutter as a group – averaging across those who are mild, moderate and severe in nature – variations in stuttering make little differences diagnostically. We further speculate that this is particularly true for those who are moderate to severe. Conversely, we believe this is less the case for children whose stuttering is very mild and closer to the boundary between being a child who does or does not stutter (CWNS). For these children whose stuttering is relatively mild, we speculate that some may appear not to stutter in one situation but stutter in another. If the above speculation is supported after manipulation of some of the more typical aspects of bi-directional communication (e.g., changes in conversational partner, location and conversational context), we will need more systematic empirical assessment of the oft-suggested notion that CWS should be examined in various situations, with various partners, etc.

Diagnostically and empirically, the frequency of stuttering-like (SLD) and nonstuttering-like disfluencies (nSLD) is commonly used to help determine the presence or absence of stuttering (e.g., Cordes & Ingham, 1994; Pellowski & Conture, 2002; Yairi & Ambrose, 2005; Yaruss, 1998). Typically, presence or frequency of stuttering is based on two fundamental measurements: (1) number of total disfluencies (SLD + nSLD) per total number of spoken words [%TD] and (2) number of SLDs per total number of spoken words [%SLD] (Yaruss, 1998). Empirical evidence suggests that for CWS, the %TD and %SLD are typically greater than 10% and 3%, respectively (see Conture, 2001; Cordes & Ingham, 1994; Sawyer & Yairi, 2006).

The ratio of SLD to TD (%SLD/TD) is another diagnostic index that has been used empirically to reliably distinguish between CWS and CWNS. On average, the %SLD/TD for CWS has been found to be approximately 65% or greater whereas the %SLD/TD for CWNS has been reported at 40% or lower (Ambrose & Yairi, 1999; Pellowski & Conture, 2002; Yairi, 1997). However, the question that remains unanswered is whether known variability in childhood stuttering significantly affects the diagnostic categories driven by the %SLD/TD.

Thus, the purpose of the present study was to determine whether variations in disfluencies of young CWS and young CWNS significantly influence their diagnosis from stutterer to nonstutterer, and vice versa. Specifically, we wanted to assess whether changes in diagnostic categories would occur as a result of changes in conversational partner (parent–clinician), location (home–clinic setting) and context (conversation–narrative).

If, for most children, the diagnostic category (CWS or CWNS) does change in association with changes in conversational partner, location and context, this would imply that basing the diagnosis of stuttering on a limited number and type of samples is contraindicated, even if the clinician has limited access to obtaining additional samples (i.e., in the home or with the parent). If, however, the diagnostic category does not change substantially, this would imply that clinicians should be able to diagnosis stuttering (or nonstuttering) in preschool-age children with some level of confidence for most children based on a limited number and type of speech samples. This latter implication would seem to provide support for those clinicians who have limited to no access to other conversational partners (i.e., the parent), other locations (i.e., home), or contexts (i.e., narrative).

Given the above, we developed two hypotheses. First, we hypothesized, for both preschool CWS and CWNS, that their respective diagnostic categories would not significantly change as a result of changes in conversational partner, context or location. Secondly, it was hypothesized that changes in these variables (i.e., conversational partner, context, and location), would have their greatest impact on children on or around the borderline for each talker group classification (CWS or CWNS).