ارتباط پیچیدگی طولی و دستوری نسبت به خطاهای سیستماتیک و غیر سیستماتیک گفتاری و لکنت زبان کودکانی که لکنت زبان دارند

The purpose of this study was to evaluate whether increased utterance length and grammatical complexity are associated with changes in frequency of systematic speech errors (i.e., phonological processes, or sound changes affecting an entire class of sounds or sound sequence [Edwards & Shriberg, 1983]), and nonsystematic speech errors (i.e., a word or string of words that apparently deviates from the speaker's intention, but that is not characteristic of the child's systematic [phonological process]) of children who stutter (CWS). Subjects were 10 boys (S's mean age = 50.6 months; SD = 13.07 months) who exhibited both stuttering and disordered phonology, each of whom was audiotaped and videotaped while interacting with his/her mother during a 30-minute play/conversation period. Twenty-five stuttered and 25 nonstuttered utterances from each subject's conversational speech sample were measured in terms of utterance length, grammatical complexity, and systematic and nonsystematic speech errors. An utterance was then categorized as “high” or “low” in length and grammatical complexity relative to the subject's median for each of the two variables, and then related to total frequency of systematic and nonsystematic speech errors. Results indicated that stuttered utterances were significantly more complex and longer than nonstuttered utterances; however, there were no significant differences in systematic and nonsystematic errors for either stuttered or nonstuttered utterances relative to the grammatical complexity or length of utterance. Findings were taken to suggest that increased length and/or grammatical complexity of an utterance does not influence the frequency of systematic and nonsystematic speech errors, but does seem, as others have shown, to influence the frequency of stuttering.

Thirty to 40% of children who stutter (CWS) reportedly have a concomitant phonological disorder (e.g., St. Louis & Hinzman 1988 and Wolk et al. 1993), considerably more than the 2 to 6% found in the general population (Beitchman, Nair, Clegg, & Patel, 1986). Although no totally adequate explanation for this fact exists, one speculation based on the Covert Repair Hypothesis (CRH) (Postma & Kolk, 1993), a hypothesis grounded in Levelt's (1989) psycholinguistic theory of speech production, suggests that both problems (stuttering and disordered phonology) relate to difficulties in phonological encoding (for an overview of the possible relationship between phonological disorders and stuttering, see Louko, Edwards, & Conture 1990, Louko, Conture, & Edwards 1999, Nippold 1990 and Paden & Yairi 1996). However, as Yaruss and Conture (1996) report, stutterings are more apt to occur on non-systematic (“slips of the tongue”) rather than systematic (phonological processes) speech errors. Thus, it is unclear what may cause both problems (stuttering and phonological disorders) to commonly co-occur in young children. Perhaps one way to better understand why stuttering and phonological disorders commonly coexist is to explore whether variables that affect one may also affect the other. For example, increased length and grammatical complexity of utterances are known to influence stuttering (e.g., Bernstein Ratner & Sih 1987, Logan & Conture 1995 and Yaruss 1999). Thus, utterance length and grammatical complexity, as well as other linguistic variables (e.g., Aram & Kamhi 1982, Camarata & Schwartz 1985, Camarata & Leonard 1986, Campbell & Shriberg 1982, Menyuk & Looney 1972, Pangos, Quine, & Klich 1979, Paul & Shriberg 1982 and Shriberg & Kwiatkowski 1980) may also influence systematic and nonsystematic speech errors. In addition, because both utterance length and grammatical complexity are known to increase with chronological age, such changes may also influence systematic and nonsystematic speech errors. Perhaps as Dell (1988) suggests, speech errors may occur because the speaker is trying to say too many words too quickly (for an overview of speech errors and self-repairs of same, see, e.g., Bredart 1991, Butterworth 1991 and Levelt 1983). In other words, when people who stutter (in)appropriately increase their utterance length (and rate of speech), it may lead them to increases in the frequency of their phonological errors. It seems reasonable to suggest that this might occur since increased utterance length requires a longer period of planning (i.e., increased time for cognitive/linguistic processing) and if this planning is rushed and/or interrupted, phonological errors, among other difficulties, may result. Although several researchers (e.g., Bernstein Ratner & Sih 1987, Guitar, Shaefer, Donahue-Kilburg, & Bond 1992, Logan & Conture 1995 and Logan & Conture 1997) have reported that increased length and grammatical complexity of utterances are associated with increased stuttering, it remains unclear what effect (if any) increased grammatical complexity and utterance length may have on associated systematic and nonsystematic speech errors in the context of stuttering. Furthermore, while findings regarding the relationship between phonological accuracy and syntactic complexity in normal and children with phonological and grammatical disorders appear equivocal Kamhi et al. 1984 and Masterson and Kamhi 1992, such relationships have not been studied with children who stutter. At present, without extending its basic assumptions, (e.g., Yaruss & Conture, 1996), the CRH appears unable to explain the apparent co-occurrence of stuttering and systematic speech errors (i.e., phonological processes) within the same individual. Thus, it seems reasonable to suggest that such co-occurrence may need to be examined from a different perspective. Perhaps by assessing how changes in systematic and nonsystematic errors are associated with changes in length and grammatical complexity of utterances, we may find comparable changes in both instances of stuttering and phonological processes. Furthermore, assessing how chronological age influences these variables may assist in describing the interaction between speech fluency and phonology. Thus, even though stuttering and phonological processes appear to have less than a direct influence on one another (e.g., stuttering infrequently occurs on words containing phonological processes [see Throneburg, Yairi, & Paden 1994 and Yaruss & Conture 1996]), these two behaviors may significantly vary as a result of changes in similar linguistic and chronological variables. In essence, it was hypothesized that increases in both systematic and nonsystematic errors may be associated with linguistic conditions that influence stuttering (i.e., increases in utterance length and grammatical complexity) because, according to the CRH, stutterings are by-products of self-repairs. In other words, if the frequency of stuttering is greater for longer and more complex utterances, than the reason for this increase may be a greater number of phonological errors, errors that are detected, repaired, and hence stuttered on. Therefore, it was the purpose of this study to examine changes in systematic and nonsystematic errors associated with changes in the length and grammatical complexity of conversational utterances of children who stutter. Specifically, the following questions were addressed: 1) Does the frequency of systematic and nonsystematic errors differ with changes in grammatical complexity of nonstuttered and stuttered utterances of children who stutter? 2) Does the frequency of systematic and nonsystematic errors differ with changes in utterance length of nonstuttered and stuttered productions of children who stutter? 3) Is there an interaction between the frequency of systematic and nonsystematic errors change in association with the four possible combinations of utterance length and grammatical complexity within the nonstuttered and stuttered utterances of children who stutter (i.e., long length, high grammatical complexity; short length, high grammatical complexity; long length, low grammatical complexity; and short length, and low grammatical complexity)? and 4) Is there are a relationship between chronological age and systematic and nonsystematic speech errors of children who stutter?

Results indicated that the frequency of stuttering increased with both increased utterance length and grammatical complexity, a finding consistent with previous studies. Furthermore, several studies including the present have all reported roughly the same number and type of phonological processes among children who stutter. However, there was no significant relationship between the frequency of systematic and nonsystematic errors, grammatical complexity, or utterance length during either stuttered or nonstuttered utterances of children who stutter. In essence, the study supports that notion that stuttering is related to grammatical complexity and utterance length (e.g., Logan & Conture 1997 and Yaruss 1999), but that changes in these linguistic variables seem to have less influence on systematic and nonsystematic errors. Thus, while it is clear that stuttering and phonological disorders co-occur frequently in young children, variables such as grammatical complexity and utterance length do not appear to readily account for such co-occurrence.Riley 1980