Language task effects

J. FLUENCY DISORD. 16 (1991), 275-287

LANGUAGE TASK EFFECTS A Comparison of Stuttering and Nonstuttering Children PEARL A. GORDON The University

of Tennessee,

Knoxville

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.

INTRODUCTION Although there is a developing body of research that has examined the relationship(s) between language and early disfluencies, little of that research has examined the effects of language-elicitation tasks on disfluenties in young children. Much of the recent research pertaining to the influences of language on disfluencies has focused on the effects of syntactic complexity. Previous research has reported that the disfluencies of nonstuttering children increase as the complexity of an utterance increases (Colburn and Mysak, 1982a, 1982b; Haynes and Hood, 1978; Pearl and Bernthal, 1980; Ratner and Sih, 1987). Additionally, this complexity effect on the disfluencies of nonstuttering children has been reported to be related to language formulation task and age (Gordon et al., 1986; Gordon and Luper, 1989). McLaughlin and Cullinan (1989) reported that disfluencies of young nonstuttering children were significantly affected by length and complexity; furthermore, they reported that significantly greater overall disfluencies and “stutterings” occurred on more complex utterances. Gordon and Luper (1989) reported that disfluencies of 3-, 5, and 7year-old nonstuttering children are significantly affected by syntactic complexity and elicitation task. They concluded that “sufficient similarities exist between the disfluencies of stuttering and nonstuttering children to suggest that the young stuttering child may exhibit similar increased Address correspondence to Pearl A. Gordon, Ph.D, The University of Tennessee, Department of Audiology and Speech Pathology, 457 South Stadium Hall, Knoxville, TN 379960740. 0 1991 by Elsevier Science Publishing Co.. Inc. 655 Avenue of the Americas, New York, NY 10010

275 0094-73OX!91/$3.50

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disfluencies” (p. 442) as syntactic complexity is varied and as languageelicitation tasks are changed. A primary motivation for examining the effects of both language-elicitation tasks and syntactic complexity on the occurrence of disfluencies in young nonstuttering children was to acquire data on nonstuttering children as a basis for comparison to young stuttering children. Ratner and Sih (1987) reported a significant relationship between disfluencies and complexity for stuttering and nonstuttering children. This relationship was further supported by a significant correlation between fluently uttered and correctly imitated sentences; that is, the least number of disfluencies tended to occur on correctly imitated sentences. The current study was designed as an investigation to compare the difference in the number of disfluencies of young stuttering and nonstuttering groups as syntactic complexity was varied in a sentence-imitation and a sentencemodeling task.

METHODS Subjects Fourteen children, seven stutterers and seven nonstutterers, served as subjects. Subjects were matched for age, t 3 months. The stuttering group (ST) ranged in age from 3 years 7 months to 7 years 11 months with a mean age of 5 years 4 months. The nonstuttering group (NST) ranged in age from 3 years 5 months to 7 years 10 months, with a mean age of 5 years 5 months. All subjects were native monolingual speakers from middle-class backgrounds. Speech, language, and other developmental and social history data were reported in a case history questionnaire that was completed by one parent of each prospective subject. All subjects demonstrated normal hearing and normal speech and language development based on normal limits performance on subject-selection language and hearing screening tests. The hearing screening was conducted in accordance with America Speech-Language Hearing Association (ASHA) guidelines for identification audiometry (1985) at 20 dB HL (re ANSI-1969) at octave frequencies between 0.5 and 4 kHz. All subjects demonstrated articulation skills within normal limits for their age as determined by performance scores on the Templin-Darley Screening Test of Articulation (Templin and Darley, 1969). Normal receptive and expressive language skills as measured by the Northwestern Syntax Screening Test (NSST) (Lee, 1971) were also demonstrated by all subjects. Only subjects who scored between the 25th and 75th percentiles on the NSST were selected as experimental subjects. The stuttering subjects were identified by referral from parents, speech-language pathologists, and the clinic director of the University

LANGUAGE TASK EFFECTS

277

of South Florida Communicative Disorders Center. All stuttering subjects were considered to be stutterers by both parents, as well as by clinical diagnosis by a certified speech-language pathologist. The stuttering diagnosis was confirmed by a review of the case history questionnaire and an evaluation of the subjects by the author (a certified speech-language pathologist). Analysis of spontaneous speech samples from the Stuttering Severity Instrument (SSI) for each subject revealed a mean of 12.7% (range 8%-21%) repetitions and prolongation of sounds and syllables and severity ratings in the mild (I subject), moderate (5 subjects), and severe (1 subject) classifications/categories. The group demonstrated a mean of 20 months (SD = 14.9) of stuttering, based on parental report. The range of stuttering history was from 3 months to 47 months. All subjects were currently enrolled in fluency treatment. None had diagnoses nor histories of concomitant speech or language disorders. stimuli

The experimental stimuli for the two language-elicitation tasks were the same as those used and described by Gordon and Luper (1989). The Imitation Task consisted of 30 sentences representing 3 syntactic constructions: (1) simple afftrmative active declarative with auxiliary + ing (SAAD) (example: The man is painting the fence); (2) future (FUT) (example: The man will paint the fence); and (3) passive (PAS) (example: The fence is painted by the man) constructions. The Modeling Task consisted of 30 sentence stimulation pictures representing the same 3 syntactic constructions. See Gordon and Luper (1989) for a more detailed description of the experimental stimuli. Procedures The subject selection screenings (i.e., hearing screening, NSST, etc.) were administered to each subject in a preliminary screening session. The subjects’ training for both tasks was completed during these screening sessions. The training consisted of practice by the subjects on six training items for each task. The training session followed the same format as the experimental session with three exceptions: (1) in the training session stimulus items and instructions were repeated as often as required for the subject to provide a correct response; (2) the experimenter gave verbal feedback and praise to the subjects to reinforce correct responses and participation; and (3) the training stimuli did not duplicate any experimental items. The experimental tasks were administered to each subject following the screening and training. The experimental tasks were administered in a fixed order, with the Sentence Imitation Task administered first. The Sentence Imitation Task was administered first to provide the subjects

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with practice on responding in complete sentences. Additionally, this order was selected to avoid a possible “picture-description” response mode from the subjects rather than the desired “construction-modeling” mode. Following practice of six training items, the subjects were required to repeat the stimulus sentences from the imitation stimuli. For the Modeling Task, the subjects were shown a picture frame in which two pictorial examples of a syntactic construction were represented. The examiner produced a sentence from one picture and the subjects were required to model that syntactic construction for the second picture (example: Experimenter [pointing to first picture on plate] “The dog is chasing the cat.” Subject [as Experimenter points to second picture] “The man is painting the fence.“). Six training items and pictures were also presented prior to administration of the Modeling Task. The subjects’ responses were tape-recorded on a Sony TCM 5000-EV portable cassette audiotape recorder. Disfluencies were identified by the classification system of Williams, Silverman, and Kools (1968). Disfluencies included interjections, partword repetitions, word repetitions, phrase repetitions, revisions, incomplete phrases, disrhythmic phonations, and tense pauses. The number of disfluencies was counted for each response sentence for each subject. Tape-recorded responses of two subjects from each group were randomly selected for restoring by the experimenter and one other independent listener. Intrajudge and interjudge agreement for the identification of (1) total disfluencies and (2) total number of sentence imitation and modeling production errors was determined by use of the Sander’s Agreement Index (Sander, 1961) (Agreement/Agreement + Disagreement = Agreement Index). The intrajudge index of agreement was 0.96 for identification of total disfluencies and was 0.99 for identification of sentence imitation and modeling production errors. The interjudge index of agreement was 0.91 for identification of total disfluencies and 0.96 for identification of sentence imitation and modeling production errors. RESULTS The total number of disfluencies for each of the three sentence constructions for all subjects on both tasks was tabulated. The total, mean, and range of disfluencies for each group on the two experimental tasks are summarized in Table 1. The Stutterers produced an overall mean of 23.14 disfluencies on the two tasks with a mean of 3.00 disfluencies on the Sentence Imitation Task and 20.14 on the Sentence Modeling Task. The Nonstutterers had an overall mean of 10.85 disfluencies on the two tasks with a mean of 2.00 on the Sentence Imitation Task and 8.86 disfluencies on the Modeling Task.

LANGUAGE

279

TASK EFFECTS

Table 1. Total (TOT), Mean (M), and Range (RNG) for Number

Disfluencies for Stuttering (ST) and Nonstuttering Sentence Imitation and Sentence Modeling Tasks Imitation

Modeling

task

GRP

TOT

M

RNG

TOT

ST NST

21 14

3.00 2.00

o-9 O-6

141 62

of (NST) Groups (GRP) on the Combined

task

tasks

M

RNG

TOT

M

RNG

20. I4 8.86

7-42 2-22

162 76

23.14 10.85

II-51 3-28

The total and mean number of disfluencies per syntactic construction were also tabulated for each subject. These data for each group are summarized in Table 2. The Stuttering Group (ST) exhibited a mean of 6.57 disfluencies on the SAAD constructions, 9.43 on the FUT, and 7.14 disfluencies on the PAS constructions for the two tasks. The NST Group had a combined mean of 3.57 disfluencies on the SAAD, 3.71 on the FUT, and 3.57 on the PAS constructions. A three-factor analysis of variance (ANOVA) with repeated measures on two factors, Task and Complexity, was utilized to determine the effects of Group, Task, and Complexity. The results are summarized in Table 3. The results revealed no significant difference between the two GROUPS (F = 3.87, df = 1, 12) nor among the three levels of syntactic Complexity (F = 0.60, df = 2, 24). However, a significant difference was observed between the two Tasks (F = 28.02, df = 1, 12, p < 0.0002). Group Effects The Stuttering Group demonstrated a mean of three disfluencies on the Imitation Task and 20.14 disfluencies on the Modeling Task and a combined mean for the two tasks of 23.14 disfluencies. The Nonstuttering Group demonstrated a mean of 2 disfluencies on the Imitation Task and 8.86 disfluencies on the modeling task; their combined mean disfluencies

Mean (M) and Range (Rng) for Number of Disfluencies for Stuttering (ST) and Nonstuttering (NST) Groups per Syntactic Construction per Task Table 2.

Imitation

task

Modeling

task

Combined

tasks

SAAD

FUT

PAS

SAAD

FUT

PAS

SAAD

FUT

PAS

M Rng NST

0.57 o-2

I .85 O-6

1.43 o-3

6.00 3-11

8.43 2-24

5.73 l-9

6.57 3-11

9.43 2-30

7.14 3-10%

M Rw

0.29 O-1

0.71 O-6

1.00 o-3

3.29 o-9

3.00 l-6

2.57 l-7

3.57 O-IO

3.71 1-8

3.57 l-10

Group ST

SAAD = Simple Active Affirmative Declarative; FUT = Future: PAS = Passive

P. A. GORDON Table 3. Summary of the Analysis of Variance for the Factors Group (GRP), Task (TSK), and Complexity (COMP) with Repeated Measures on Task and Complexity

Source Total Between Subjects GRP Erl-Or” Within subjects TSK COMP GRP x TSK GRP x COMP TSK x COMP GRP x TSK x COMP Error” Errorb Error’

ss 1215.67 361.34 88.05 273.29 854.33 336.00 8.88 61.71 7.1-l 13.50 7.19 143.96 177.29 98.04

df

MS

83 13

-

12 70

2 2 2 12 24 24

F

P

-

-

88.05 22.17

3.87

336.00 4.44 61.71 3.58 6.15 3.89 11.99 7.39 4.09

28.01 0.60 5.14 0.49 1.65 0.95

-

co.07

10.0002 NS 10.04 NS NS NS

-

on the two tasks was 10.85. The main effect was not significant at the 0.05 level; however, it was significant at a somewhat lower level (F = 3.87, df = 1, 12, p < 0.07).

Complexity Effects The earlier reported disfluency/complexity effect was not replicated in this study. Although the subjects demonstrated a modest trend for more disfluencies on the FUT and PAS constructions (see Table 2), this difference was not statistically significant.

Task Effects The Modeling Task significantly affected the occurrence of disfluencies in the speech of both young stuttering and nonstuttering subjects. More disfluencies occurred for both groups within the Modeling Task than on the Sentence Imitation Task. (See Figure 1.) The effects of task were examined further by analyzing the relationships between the number of sentence imitation errors and the number of sentence-modeling errors and number of disfluencies. Pearson Product-Moment correlations were computed for the total number of sentence production errors and total number of disfluencies for each task, across subjects and for each Group. The correlation (r = +0.42, p > 0.05) between the number of sentences incorrectly imitated (n = 30) and the total number of disfluencies (n = 35) on the Sentence Imitation Task was

LANGUAGE

281

TASK EFFECTS

0

25--

nonstutterers 0 stutterers

u-l

w

0 5

20--

3

IL

E 15-L 0 E

lO--

5 Z z

5--

s I

St TASK Figure 1. Mean number

and Sentence

SM TASK

of disfluencies produced on the Sentence Imitation Modeling (SM) Tasks by stuttering and nonstuttering groups.

(SI)

not significant. The correlation (I. = +0.53, p < 0.05) between the number of sentences incorrectly modeled (n = 252) and the number of disfluencies (n = 203) on the Sentence Modeling Task was significant. The group data indicated a nonsignificant correlation (r = +0.39, p > 0.05) between the number of sentences incorrectly imitated (n = 12) and total number of disfluencies (n = 14) on the Sentence Imitation Task for the Nonstutterers. Likewise, the correlation (r = +0.27, p > 0.05)between the number of sentences incorrectly modeled (n = 122) and the number of disfluencies (n = 62) on the Sentence Modeling Task was also nonsignificant for the Nonstuttering Group. For the Stuttering Group, the correlation (r = +0.41, p > 0.05) between the number of sentences incorrectly imitated (n = 18) and the total number of disfluencies (n = 21) was also nonsignificant. Whereas, a significant positive correlation existed (r = +0.88,p < 0.005)between the number of sentences incorrectly modeled (n = 130) and the number of disfluencies (n = 141) on the Sentence Modeling Task for the Stuttering subjects.

282

P. A. GORDON

Interactions As shown in Table 3, there was a significant group x task interaction (F = 5.14, df = 1, 12, p < 0.04). The difference between the two groups was not consistent across the two tasks. F-tests for simple effects indicated no significant difference between the two groups on the Imitation Task; however, the Stuttering Group was significantly different (F = 35.60, df = 1,36, p < 0.01) from the Nonstuttering Group on the Modeling Task. This difference is also illustrated in Figure 1.

DISCUSSION Group Effects Although the stuttering subjects in this study exhibited more disfluencies (See Figure 1) on both tasks than their nonstuttering peers, this difference was not statistically significant. Why was there no significant difference between the two groups? First, we must consider that the criterion for determining group differences was based on a mean number of disfluenties and disfluencies were defined based on the Williams et al. (1968) classification criteria. Thus, the result does not reflect a difference between the two groups for “stuttering” types of disfluencies, but for all disfluencies, “stuttered” and “normal.” Figure 2 illustrates a comparison of the two groups for frequency of disfluencies by type. The Stuttering Group exhibited more of all types of disfluencies than the Nonstuttering Group, with the exception of revisions (a normal type of disfluency); but, the figure illustrates that the two groups were markedly different for the number of some specific types of disfluencies. For “stuttered” types of disfluencies, the Stuttering Group had noticeably more part-word repetitions and disrhythmic phonations. The Stuttering Group exhibited markedly more word repetitions, a common feature of both stuttering and nonstuttering children, than the Nonstuttering Group when this comparison was made. The significant group x task interaction also indicates that both group and task are related to the number of disfluencies. As illustrated in Figure 1, the mean number of disfluencies was greater for the stutterers than the nonstutterers on both tasks; however, the difference between the two groups was only significantly greater on the Modeling Task. Further explanation for the nonsignificant group difference in frequency of disfluencies can be made by examination of the case histories of the stuttering subjects. Five of the seven children within the Stuttering Group had mean durations of stuttering of 11.5 months. The remaining two subjects (also the oldest subjects in the group) had been stuttering 33 and 47 months, respectively. So the majority of the stuttering subjects were rel-

283

LA1VGUAGE TASK EFFECTS

65 60

-

0

55 50 45

-

40

-

35 30

-

Groups Nonstutterers m Stutterers

25 20 15 10 5 0 ,l,a INTJ

PWR

WR

PR

IL&

RV

DP

TP

TYPES OF DISFLUENCIES Figure 2. Comparison

of stuttering

and nonstuttering

groups for frequency of

disfluencies.

atively early stutterers. Additionally, the five subjects within the group who had the shorter interval of stuttering (mean = 11.5 months) were also the younger subjects in the Stuttering Group (mean age = 60.4 months, an age period still marked by a relatively high occurrence of normal disfluencies). The presence of normal disfluencies, plus stuttered disfluencies, in the speech of the majority of the stuttering subjects may account for more overlap between the two groups for number of disfluenties; and thus, the nonsignificant group effect. Additionally, it can not be ignored that the Nonstuttering Group also exhibited some of the types of disfluencies more commonly associated with stuttering children (See Figure 2). As Conture pointed out “. . . the distinction between stuttering and stutterer is blurred . . . as much as we would like absolute precise cut-offs for deciding who is and who is not a stutterer, the behavioral overlap between the two populations makes this a difficult proposition” (Conture, 1990, p. 11). The nonsignificant group difference in this study illustrates that “behavioral overlap” to which Conture refers.

P. A. GORDON

284

A final explanation that should be considered when attempting to explain the failure to identify a difference between the two groups, of course, is the small sample size when examining these data. There were only seven subjects in each group; a significant difference may have been revealed had the subject pool been larger. The ANOVA results indicating a significant difference at the 0.07 level suggest that a more highly significant difference may have been evident with a larger data pool. Complexity Effects Only three levels of complexity were represented in the experimental tasks; thus, as Ratner and Sih (1987) suggested, these may not have been sufficient to measure the effects of syntactic complexity on disfluent speech behavior. The age of the subjects within the groups represents another possible explanation of these results. Although the mean age of the two groups was 5 years, individual subjects within the groups differed in their linguistic maturity. That is, the manner in which the youngest subject (age 3 years 5 months) handled the syntactic complexity within the two tasks was different from that of the older subject (age 7 years, 11 months). This age difference for managing syntactic complexity was reported by Gordon and Luper (1989) and is further illustrated in the failure to replicate syntactic complexity effects in this study. Studies in which a complexity effect has been reported have either included singleage groups of subjects (Gordon et al., 1986; Gordon and Luper, 1989; Haynes and Hood, 1978; McLaughlin and Cullinan, 1989), younger subjects (Colburn and Mysak, 1982a, 1982b; Pearl and Bernthal, 1980), or a wider range of complexity within the experimental stimuli (Ratner and Sih, 1987). The use of the mixed age group of subjects might be described as a weakness of the present study. Task Effects This finding was first reported by Gordon et al. (1986) and again by Gordon and Luper (1989). In their stated rationale for examining the relationship of disfluencies to utterance length and linguistic complexity within a modeling procedure, McLaughlin and Cullinan (1989) used this finding to support their use of an elicitation task that more closely approximated conditions of natural communication. They stated: the results of Gordon et al. (1986) call into question the validity of fluency and language data obtained through elicited imitation. . . . Certainly, in attempting to examine the relationship between disfluency and linguistic complexity, a paramount consideration should be the naturalness with which both variables are sampled.” (pp. 18-19)

LANGUAGE

TASK EFFECTS

285

It has been suggested earlier by Gordon and Luper (1989) that a sentence-modeling task may require linguistic processing skills that are more similar to those required of children when they generate and formulate spontaneous utterances. The relationship between language, stuttering, fluency, and disfluency has not, and the author contends will not, be identified as a singular simple “connection.” When we examine the significant difference between the two tasks within this study, we find one additional variable that is a factor in the language connection. The language processing or language formulation demands of the Modeling Task appeared to tax the capacities of both the stuttering and nonstuttering subjects. Both groups of subjects exhibited more production errors on the specific constructions within the Modeling Task than on the Sentence Imitation Task-another possible sign of breakdown as a result of the demands of the task. If one is interested in determining whether or not a child’s fluency is affected by sentence complexity, that effect can best be identified in an elicitation task in which the linguistic demand to formulatefluent complex utterances exceeds the child’s capacities for both fluent and complex utterances. The sampling task or language-elicitation task is a factor as language formulation represents a linguistic demand. As syntactic complexity is manipulated within such a task, disfluency can be measured as a manifestation of the child’s capacity for fluency within the context of the defined syntactic complexity demand and the defined language formulation demand. As pointed out by Adams (1990), the Demands and Capacities model does not require that we presume that all stuttering children have deficient or abnormal linguistic skills or that unusually high linguistic demands are placed on them. It only requires that we accept that fluency breaks down when demands for fluency exceed the capacities for fluency. Adams offered a range of hypothetical conditions to illustrate the relationship between demands and capacities. In this study, a number of possible conditions might be proposed to illustrate the possible language demands and capacities related to fluency break downs in young stuttering and nonstuttering children. Within the framework of Adams’ proposed conditions it appears that the abnormally high, linguistic demands of the Modeling Task may have exceed the subjects’ normal capacities. Furthermore, it appears that the demands of the Modeling Task had a greater affect on the Stuttering Group. Future research should examine differences in the type of disfluencies exhibited by stuttering and nonstuttering children as syntactic complexity and task complexity are manipulated. Additionally, as Adams (1988) suggested in his most recent 5-year retrospective, future research should take into account the “complex interaction between fluency, disfluency, grammatical complexity, age, and mode of experimental responding. . .” (p.

286

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402). If viewed within the Demand/Capacities framework, the language connection is not a static connection, but apparently a network of connections that are adjusted and altered as the child’s capacities for fluency and language develop.

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