Dichotic speech perception: A comparison between stuttering and nonstuttering children

A stop consonant-vowel dichotic listening task was administered to 90 right- handed boys, 30 in each age group of 5, 7, and 9 yr. Half in each group were stutterers, half nonstutterers. Two and a half times as many stutterers as nonstutterers were found to display either a left-ear advantage (LEA) or no ear advantage (NEA). This finding suggested a greater tendency on the part of stutterers, as opposed to nonstutterers, for reversed or bilateral representation of the auditory speech areas of the brain. In addition, both stutterers and nonstutterers displayed significant developmental increases in the number of times they were able to identify both dichotic speech stimuli, thereby supporting the hypothesis of an age-related increase in children's total information processing capacity. The results are discussed in terms of the differences between stutterers and nonstutterers with respect to the issues of motor representation, cognitive modes, and higher-order linguistic processes.     

A tachistoscopic study of hemispheric processing in stuttering and nonstuttering children

Hemispheric processing, expressed as mean reaction time to various visual stimuli presented to the left and right visual fields, was investigated in eighteen stuttering and nonstuttering children. Tachistoscopic procedures were used to present linguistic stimuli (words and nonwords) as well as nonlinguistic stimuli (familiar and unfamiliar geometric figures) to the visual fields. Subjects responded by pressing a telegraph key when they perceived a real word or a familiar geometric figure. They were to make no response when they perceived nonwords or unfamiliar geometric figures. Faster reaction times were taken as an index of the most efficient or dominant hemisphere for a given task. No significant differences were found in mean reaction times for groups, visual fields, type of task, nor any of their interactions. Likewise, the data on accuracy also did not suggest that a larger proportion of stutters responded more accurately when linguistic stimuli were presented to the right hemisphere. Based on mean reaction times and on accuracy data, the stuttering and nonstuttering children performed with similar efficiencies and processing patterns.     

Oral form perception skills of stuttering and nonstuttering children measured by stereognosis

It has been suggested that a primary causative factor in stuttering is a disordered feedback mechanism. Some researchers have explored the relationship between stuttering and the integrity of the feedback mechanism through studies of oral form perception. The studies on the relationship between stuttering and oral form perception have been carried out largely on adult populations. The results of those studies have been contradictory. The purpose of this study was to explore the relationship of stuttering to oral form perception in a school-age population. The results are in agreement with previous studies which have indicated that stutters do not do as well as non-stutters on tasks of oral form perception.     

A comparison of interactions between stuttering children,nonstuttering children,and their mothers

Conversations between eight stuttering children, eight nonstuttering children, and their respective mothers were observed, recorded, and analyzed. Results indicate that mothers of stutterers made significantly more demands, commands, and requests when talking with their children; on the other hand, mothers of nonstutterers uttered more statements. Additional findings reveal that the stuttering children were more verbal, while their nonstuttering peers communicated more frequently with gestures and other means of expression. The data are discussed in light of theories that parent-child interactions are critical to the onset and development of stuttering. Implications for clinical management of young stutterers are presented.     

Language task effects A comparison of stuttering and nonstuttering children

This study examined the effects of language-elicitation tasks and syntactic complexity on disfluencies of stuttering and nonstuttering children. The total disfluencies occurring on the production of imitated and modeled sentences of varying syntactic complexity was compared for the two groups. Results indicated a significant task effect, but nonsignificant complexity and group effects. Results are discussed within the framework of the “Demands and Capacities” model.     

Performance differences between stuttering and nonstuttering subjects on a sound fusion task

This study investigated the possibility that there are central auditory level processing differences between stutterers and nonstutterers. The experimental subjects were eight male and three female stutterers ranging in age from 20–45 yr, with a mean age of 31.2 yr. The control group consisted of the same number of males and females, ranging in age from 20–45 yr, with a mean age of 30.1 yr. Each subject participated in a sound fusion task under three variable conditions: 1) group performance (nonstutterers vs. stutterers); 2) ears (right vs. left); and 3) lead-time presentation (0–100 msec). Statistically significant differences were found for lead-time presentation.     

Communicative behavior of mothers of stuttering and nonstuttering high-risk children prior to the onset of stuttering

This portion of a multiyear prospective study was designed to investigate the communicative style, speaking rate, and language complexity of 93 mothers of preschool children with a parental history of stuttering. At the initial session none of the children sampled was regarded as being a stutterer. One year later, 26 of the children were classified as stutterers. Statistical analyses revealed that prior to the onset of stuttering the mothers of these children did not differ from the mothers of the children who continued to be seen as nonstutterers with respect to either communicative style or speaking rate. The only significant difference between the two groups of mothers was the complexity of their language. The pre-onset mean lengths of utterance (MLUs) of the mothers of children who later came to be regarded as stutterers were significantly shorter than those of the mothers whose children continued to be viewed as being fluent. These findings suggest that the communicative behavior of mothers of normally fluent children do not contribute to the development of stuttering.     

Voice reaction time of stuttering and nonstuttering children and adults

The voice reaction time (VRT) of 5-yr old, 9-yr old, and adult stutterers and nonstutterers was investigated. Subjects initiated the sound / Λ / in response to fifty-five 1000-Hz tones of 1 sec duration. The tones were presented in five equal sets of 11 tones each with the silent intervals between the tones randomly selected to be 3, 4, 5, or 6 sec. Data analysis was based on responses 2–11 for each set. The VRTs for both the stutterers and the nonstutterers decreased significantly as an inverse function of age, with the largest decrease in reaction time occuring between 5 and 9 yr. The VRTs for the stutterers, however, were significantly slower than those of the nonstutterers at each of the three age levels. The results suggest that observed disruption in the laryngeal behavior for at least some stutterers may not result from the development of stuttering with age, but may contribute to early difficulty in the child's ability to produce fluent speech. Consideration of central factors are discussed.     

A comparative study of speech disfluencies in nonstuttering black and white college athletes

Speech samples elicited from nonstuttering black subjects and from nonstuttering white subjects were compared for degree and nature of disfluencies. Ninety-two male college athletes were screened in the areas of articulation, voice, fluency, and hearing. A 100-word conversational speech sample and a 200-word reading sample were elicited from subjects who passed the screening (28 black athletes and 29 white athletes). Both the spontaneous speech samples and the reading samples were rated for disfluency by three clinically certified speech-language pathologists. The black subjects exhibited significantly more total disfluencies in reading than did the white subjects; in terms of disfluency differences by type, the black subjects displayed significantly more word and phrase repititions. No significant differences were found between the subject groups for total disfluencies in conversation, although the white subjects did display significantly more hesitations. Grammatically, both subject groups were most disfluent on pronouns, nouns, adverbs, verbs, and adjectives, consistent with research findings on the loci of speech disfluencies.     

Perceptual analyses of stuttering and nonstuttering children's fluent speech productions

Several investigators have reported a significant perceptual difference between adult stutterers' and nonstutterers' fluent speech productions. However, there is only limited information concerning the perceptual evaluation of stuttering and nonstuttering children's fluent speech. Therefore, in this study identical fluent sentences from nine stuttering children (mean age = 6 yrs, 8 mos) and nine nonstuttering children matched individually for sex and age (within 6 mos) were analyzed perceptually in both a paired- and single-stimulus paradigm by 12 sophisticated listeners. Individual subject analyses revealed that only one-half or fewer of the stutterers could be discerned in either paradigm. In the remaining cases, either no discrimination could be made or a nonstutterer was incorrectly identified as a stutterer. When averaged for subject group comparison, these findings indicated that listeners could not discriminate between the two groups. Possible explanations for this discrepancy in results between child and adult stutterers are proposed.     

Traits attributed to stuttering and nonstuttering children by their mothers

Traits attributed to 34 stuttering and 34 nonstuttering male children by their mothers using an adjective checklist were studied. Mothers of school-aged male stutterers were found to perceive their children as being more insecure, sensitive, anxious, withdrawn, fearful, and introverted than did mothers of nonstutterers. It was concluded that although research has not demonstrated a characteristic stuttering personality, stutterers continue to be perceived as having characteristic personality patterns.     

Voice initiation and termination time in stuttering and nonstuttering children

Voice initiation time (VIT) and voice termination time (VTT) was measured in seven stuttering and eight nonstuttering children ranging in age from 4 yr, 6 mo to 6 yr, 10 mo. The experimental task was the production of /a/ in response to a 1000-Hz pure tone. Voice initiation time was defined as the period of time elapsing between the onset of the auditory stimulus and the onset of the subject's response of /a/, as displayed on an oscilloscope. Voice termination time was defined as the latency between termination of the stimulus tone and the point at which the oscilloscopic signal decreased by 90%. No statistically significant differences were found between the two groups with respect to either VIT or VTT. In addition, no apparent relationships were present among VIT, VTT, or stuttering severity.     

The effects of simulated stuttering and prolonged speech on the neural activation patterns of stuttering and nonstuttering adults

Functional magnetic resonance imaging was used to investigate the neural correlates of passive listening, habitual speech and two modified speech patterns (simulated stuttering and prolonged speech) in stuttering and nonstuttering adults. Within-group comparisons revealed increased right hemisphere biased activation of speech-related regions during the simulated stuttered and prolonged speech tasks, relative to the habitual speech task, in the stuttering group. No significant activation differences were observed within the nonstuttering participants during these speech conditions. Between-group comparisons revealed less left superior temporal gyrus activation in stutterers during habitual speech and increased right inferior frontal gyrus activation during simulated stuttering relative to nonstutterers. Stutterers were also found to have increased activation in the left middle and superior temporal gyri and right insula, primary motor cortex and supplementary motor cortex during the passive listening condition relative to nonstutterers. The results provide further evidence for the presence of functional deficiencies underlying auditory processing, motor planning and execution in people who stutter, with these differences being affected by speech manner.     

Reading ability and disfluency in stuttering and nonstuttering elementary school children

This study was aimed at comparing the reading abilities of elementary school children who stutter with their nonstuttering peers. Forty-four stuttering children from four grade levels were matched with a group of normally fluent controls on the basis of age, sex, and grade level. Reading ability was assessed by means of three Dutch standardized tests yielding a total of six scores. Disfluency scores during oral reading were also obtained for each subject. Results indicated significant differences between the two groups on reading rate and reading errors, but not on reading comprehension. Analysis of reading errors did not show qualitative differences among subjects: stuttering and nonstuttering children made the same kinds of reading errors. Similarly, the two groups did not differ with respect to performances at different grade levels. Among both groups of subjects performances became better with increasing grade on four of the six measures. Correlational analyses indicated that the measures of reading ability used in this study were significantly associated with frequency of disfluency for the nonstuttering children. In contrast, no significant relationship was found between reading ability and disfluency in the stuttering group, except for reading rate. Results are discussed with respect to the possible interaction between verbal performance and linguistic competence in reading ability measures, particularly for the stuttering child.     

Timing and stiffness in speech motor control of stuttering and nonstuttering adults

Twelve stutterers and 12 nonstutterers were investigated in order to measure speech movements of the jaw. They spoke the nonsense word /papapas/ with stress on either the first or second syllable and with three speech rates (fast, moderate, and slow). During these trials, jaw movements were analyzed with a selspot-like optical tracking system. It was shown that stutters and nonstutterers applied the same strategies for realizing jaw movements of accented and unaccented syllables. The first strategy (stiffness variation) was used to achieve fast jaw movements while the second strategy (timing) was used in order to realize jaw movements for accented syllables. These results were taken as evidence for the assumption that, in general, stutterers and nonstutterers used the same control strategies when speaking fluently. However, it was also evident that stutterers produced lengthened jaw opening and closing durations as well as reduced peak velocities and maximal opening and closing displacements. This deviating movement pattern was supposed to reflect motor compensations necessary to achieve fluent speech rather than anomalies of the speech neuromotor system.     

The effect of syntactic structure upon speech initiation times of stuttering and nonstuttering speakers

Past research has shown that adults who stutter tend to be slower than adults who do not stutter at initiating various speech-like movements, nonsense syllables, words, short phrases, and simple sentences. The present study sought to extend this research by examining the effect that syntactic structure has upon stutterers' and nonstutterers' ability to initiate sentences. Eleven persons who stutter (mean age=22.2 years) and 11 nonstuttering controls (mean age=23.3 years) read, rehearsed, and then reproduced a series of 96 sentences within a simple reaction time paradigm. The sentences were presented in four blocks of 24 sentences, and each block contained one version of each of the 24 base sentences. Versions of the base sentences varied, from simple to complex, along four levels of syntactic complexity. Results indicated that speech initiation times (SITs) were significantly longer for participants who stutter than they were for nonstuttering controls for three of the four sentence types. There was no significant difference in SITs across the four sentence types for either group. Among the stuttering participants, there was no significant correlation between stuttering severity and overall initiation time for the sentences. Consistent with other studies, the present findings suggest that persons who stutter are slower than persons who do not stutter at planning and/or initiating motor movements associated with speech production. EDUCATIONAL OBJECTIVES: The reader will be able to (1). describe how persons who stutter typically perform during various reaction time tasks, (2). explain the rationale for examining the effect of syntactic complexity upon speech initiation time, (3). discuss how the speech initiation times of persons who stutter compare to those of persons who do not stutter during the production of various types of sentences, (4). identify future research needs in this area.     

A pilot study into a possible relationship between diet and stuttering

PurposeThere are theoretical and empirical reasons to consider a potential role for copper metabolism in the brain in how it could influence stuttering. However, a link between stuttering and dietary intake has never been researched in a systematic way. This pilot study therefore aimed to explore a possible association between ingested amounts of copper and thiamine (vitamin B1) with stuttering frequency using a double blind cross-over longitudinal paradigm.Methods19 adults who stutter between 20 and 51 years old filled out an online survey for 9 consecutive weeks. The survey consisted of self-assessed fluency and mood state scales, as well as food journals. After 4 weeks, the participants consumed either copper or thiamine supplements for 2 weeks, followed by a 1-week washout period, and another period of two weeks taking the other supplement. Formal speech assessments were done pre/post baseline and at the end of each supplement intake. Participants were not informed about the nature of the supplements during the experiment and the investigators were blinded to the order of the supplements.ResultsThe results demonstrated that copper and thiamine had no measurable effect on the amount of stuttering (self and formal assessments) but there was a moderate, significant correlation between mood state and fluency.ConclusionThe findings do not support notions of dietary influences of ingested copper or thiamine on stuttering but do provide modest support for a relationship between variations in stuttering and self-perceived anxiety.     

Hemispheric alpha asymmetries of stuttering males and nonstuttering males and females for words of high and low imagery

Alpha hemispheric asymmetries of nonstuttering males, nonstuttering females, and stuttering males were explored with electroencephalographic procedures during exposure to two lists of one-syllable words which the subjects were required to recall following presentation. One word list contained low-imagery words while the other contained high-imagery words. Stuttering males were found to have significantly less alpha in their right hemispheres, suggesting right hemispheric processing strategies. This finding was interpreted as supporting the “segmentation dysfunction” explanation of stuttering suggested by Moore and Haynes (1979b). Nonstuttering males showed less left than right alpha while nonstuttering females revealed no difference between their right and left hemispheres. Differences between nonstuttering males and females are discussed as being task and stimuli dependent relative to the segmental/nonsegmental nature of both task and stimuli. Differential hemispheric asymmetries for words of high or low-imagery were not observed.