Effects of time-interval judgement training on real-time measurement of stuttering

The purpose of this study was to investigate whether a previously developed interval-based training program could improve judges' stuttering event judgments. Two groups of judges made real-time stuttering event judgments (computer-mouse button presses) in 3 to 6 trials before the response-contingent judgment training program and in another 3 to 6 trials after training, for recordings of 9 adults who stuttered. Their judgments were analyzed in terms of number of stuttering events, duration of stuttering, and 5-s intervals of speech that could be categorized as judged (or not judged) to contain stuttering. Results showed (a) changes in the amount of stuttering identified by the judges; (b) improved correspondence between the judges' identifications of stuttering events and interval-based standards previously developed from judgments made by experienced, authoritative judges; (c) improved correspondence between interval-based analyses of the judges' stuttering judgments and the previously developed standards; (d) improved intrajudge agreement; (e) improved interjudge agreement; and (f) convergence between the 2 judge groups, for samples and speakers used during training tasks and also for other speakers. Some implications of these findings for developing standardized procedures for the real-time measurement of stuttering are discussed.

The Gab1 protein is a docking site for multiple proteins involved in signaling by the B cell antigen receptor

Gab1 is a member of the docking/scaffolding protein family which includes IRS-1, IRS-2, c-Cbl, p130(cas), and p62(dok). These proteins contain a variety of protein-protein interaction motifs including multiple tyrosine residues that when phosphorylated can act as binding sites for Src homology 2 (SH2) domain-containing signaling proteins. We show in the RAMOS human B cell line that Gab1 is tyrosine-phosphorylated in response to B cell antigen receptor (BCR) engagement. Moreover, tyrosine phosphorylation of Gab1 correlated with the binding of several SH2-containing signaling proteins to Gab1 including Shc, Grb2, phosphatidylinositol 3-kinase, and the SHP-2 tyrosine phosphatase. Far Western analysis showed that the SH2 domains of Shc, SHP-2, and the p85 subunit of phosphatidylinositol 3-kinase could bind directly to tyrosine-phosphorylated Gab1 isolated from activated RAMOS cells. In contrast, the Grb2 SH2 domain did not bind directly to Gab1 but instead to the Shc and SHP-2 associated with Gab1. We also show that Gab1 is present in the membrane-enriched particulate fraction of RAMOS cells and that Gab1/signaling protein complexes are found in this fraction after BCR engagement. Thus, tyrosine-phosphorylated Gab1 may recruit cytosolic signaling proteins to cellular membranes where they can act on membrane-bound targets. This may be a critical step in the activation of multiple BCR signaling pathways.

Activation of the Rap1 GTPase by the B cell antigen receptor

The B cell antigen receptor (BCR) activates Ras, a GTPase that promotes cell proliferation by activating the Raf-1/MEK/ERK signaling module and other signaling enzymes. In its active GTP-bound form, the Rap1 GTPase may act as a negative regulator of Ras-mediated signaling by sequestering Ras effectors (e.g., Raf-1) and preventing their activation. In this report, we show that BCR engagement activates Rap1 and that this is dependent on production of diacylglycerol (DAG) by phospholipase C-gamma. Activation of Rap1 by the BCR was greatly reduced in phospholipase C-gamma-deficient B cells, whereas both a synthetic DAG and phorbol dibutyrate could activate Rap1 in B cells. We had previously shown that C3G, an activator of Rap1, associates with the Crk adaptor proteins in B cells and that BCR engagement causes Crk to bind to the Cas and Cbl docking proteins. However, the DAG-dependent pathway by which the BCR activates Rap1 apparently does not involve Crk signaling complexes since phorbol dibutyrate could activate Rap1 without inducing the formation of these complexes. Thus, the BCR activates Rap1 via a novel DAG-dependent pathway.

Children recovered from stuttering without formal treatment: perceptual assessment of speech normalcy

Current evidence suggests that young children who recover from stuttering are essentially stutter-free. However, there is no evidence to indicate if their speech is perceptually indistinguishable from normally fluent peers or whether they retain perceptually unusual speech. One important example of recovery from stuttering is children who have recovered without receiving formal treatment. An investigation was conducted to determine if the speech of these children is perceptually different from the speech of children who have never stuttered. Speakers consisted of 10 preschool and early school-age children documented as recovered from stuttering without benefit of formal treatment. In a series of studies they were compared with 10 children who had never stuttered. Three groups of judges-sophisticated, unsophisticated, and experienced-were separately asked, using videotaped speech samples of the children, to decide which samples were from children who used to stutter. Results revealed that the children who recovered from stuttering were perceptually indistinguishable from the normal controls. The same result was obtained regardless of whether the samples were presented in paired-stimulus or single-stimulus mode. Two of the groups of judges were also instructed to rate the speech naturalness of the speech samples. The speakers were not distinguished on this measure either. Methodological issues and the implications of the findings are discussed.

Identifying the authoritative judgments of stuttering: comparisons of self-judgments and observer judgments

Reliable and accurate stuttering measurement depends on the existence of unambiguous descriptions or exemplars of stuttered and nonstuttered speech. The development of clinically meaningful and useful exemplars, in turn, requires determining whether persons who stutter judge the same speech to be stuttered that other observers judge to be stuttered. The purpose of these experiments, therefore, was to compare stuttering judgements from several sources: 15 adults who stutter, judging their own spontaneous speech; the same adults who stutter, judging each other's speech; and a panel of 10 authorities on stuttering research and treatment. Judgments were mode under several conditions, including self-judgments made while the speaker was talking and self- and other-judgements made from recordings in continuous and interval formats. Results showed substantial differences in stuttering judgments across speakers, judges, and judgment conditions, but across-task comparisons were complicated by low self-agreement for many judges. Some intervals were judged consistently by all judges to be Stuttered or Nonstuttered, across multiple conditions, but many other intervals were either not assigned replicable judgments or were consistently judged to be Nonstuttered by the speaker who had produced them but were not assigned consistent judgments by other judges. The implications of these findings for stuttering measurement are considered.

Experimental investigation of the effects of frequency-altered auditory feedback on the speech of adults who stutter

A series of single-subject experiments evaluated the effects of frequency-altered auditory feedback (FAF) on the speech performance of four adult males who stutter. Using alterations of plus or minus one octave, FAF was compared with normal auditory feedback (NAF) in oral reading and spontaneous speech with measurements made of stuttered intervals, stutter-free speech rate, and speech naturalness. The effects of extended FAF conditions on spontaneous speech were also evaluated for two subjects who demonstrated a positive response to FAF. Results showed no consistencies across subjects in responses to FAF: One subject showed no response, another produced an initial temporary response, a third showed a deterioration in speech quality with minimal reductions in stuttering, and a fourth displayed substantial and sustained improvements in speech performance. Some implications of these findings for current research and theory about the relationship between stuttering and FAF are discussed.

Effect of speech dialect on speech naturalness ratings: a systematic replication of Martin, Haroldson, and Triden (1984)

This study investigated the effect of speech dialect on listeners' speech naturalness ratings by systematically replicating Martin, Haroldson, and Triden's (1984) study using three groups of speaker samples. Two groups consisted of speakers with General American dialect--one with persons who stutter and the other with persons who do not stutter. The third group also consisted of speakers who do not stutter but who spoke non-General American dialect. The results showed that speech naturalness ratings distinguished among the three speaker groups. The variables that appeared to influence speech naturalness ratings were type of dialect, speech fluency, and speaking rate, though they differed across speaker groups. The findings also suggested that strength of speech dialect may be a scaleable dimension that judges can rate with acceptable levels of reliability. Dialect may also be an important factor that needs to be incorporated or controlled within systems designed to train speech naturalness ratings. It may also be an important factor in determining the extent to which stuttering treatment produces natural sounding speech.

B cell antigen receptor signaling induces the formation of complexes containing the Crk adapter proteins

Crk proteins are Src homology (SH) 2/SH3-containing adapter proteins that can mediate the formation of signaling complexes. We show that engaging the B cell antigen receptor (BCR) on the RAMOS B cell line caused both Crk-L and Crk II to associate with several tyrosine-phosphorylated proteins. We identified two of these phosphoproteins as Cas and Cbl and showed that both bound to the Crk SH2 domain after BCR engagement. BCR ligation also increased the amount of Crk proteins in the particulate fraction of the cells and induced the formation of Crk.Cas and Crk.Cbl complexes in the particulate fraction. We propose that tyrosine phosphorylation of membrane-associated Cas and Cbl creates binding sites for the Crk SH2 domain and recruits Crk complexes to cellular membranes. Thus, Crk proteins may participate in BCR signaling by using their SH2 domains to direct the interactions and subcellular localization of proteins that bind to their SH3 domains. In RAMOS cells, we found that the SH3 domains of Crk-L and Crk II bound C3G. Since C3G activates Rap, a negative regulator of the Ras pathway, Crk proteins may participate in regulation of Ras signaling by the BCR.

Functional-lesion investigation of developmental stuttering with positron emission tomography

Positron emission tomographic (PET) H2(15)O measurements of resting-state regional cerebral blood flow (CBF) were obtained in 29 right-handed men, 10 of whom stuttered and 19 of whom did not. PET images were analyzed by sampling 74 regions of interest (ROIs), 37 per hemisphere. ROI placement was guided both physiologically and anatomically. Physiological ROI placement was based on speech motor activations. Anatomical ROIs were positioned by reference to a stereotactic, neurosurgical atlas with positions confirmed and finely adjusted by co-registered magnetic-resonance images (MRIs). For all subjects, PET and MR images were normal to visual inspection. Highly significant (p < 0.0001) between-region and between-hemisphere effects were found for both groups, as have been previously reported for normal subjects, but no significant between-group differences were found for any regional CBF values. Analysis by a laterality index found a weakly significant between-groups effect (p = 0.04) that was isolated to five regions, four of which are implicated in speech or hearing. However, these regional laterality effects showed no consistent directionality, nor did these regions have absolute differences in regional blood flow between groups. Present findings do not support recent suggestions that developmental stuttering is associated with abnormalities of brain blood flow at rest. Rather, our findings indicate an essentially normal functional brain terrain with a small number of minor differences in hemispheric symmetry.

A PET study of the neural systems of stuttering

The cause of stuttering is unknown. Failure to develop left-hemispheric dominance for speech is a long-standing theory although others implicated the motor system more broadly, often postulating hyperactivity of the right (language nondominant) cerebral hemisphere. As knowledge of motor circuitry has advanced, theories of stuttering have become more anatomically specific, postulating hyperactivity of premotor cortex, either directly or through connectivity with the thalamus and basal ganglia. Alternative theories target the auditory and speech production systems. By contrasting stuttering with fluent speech using positron emission tomography combined with chorus reading to induce fluency, we found support for each of these hypotheses. Stuttering induced widespread overactivations of the motor system in both cerebrum and cerebellum, with right cerebral dominance. Stuttered reading lacked left-lateralized activations of the auditory system, which are thought to support the self-monitoring of speech, and selectively deactivated a frontal-temporal system implicated in speech production. Induced fluency decreased or eliminated the overactivity in most motor areas, and largely reversed the auditory-system underactivations and the deactivation of the speech production system. Thus stuttering is a disorder affecting the multiple neural systems used for speaking.

Time-interval measurement of stuttering: establishing and modifying judgment accuracy

The purpose of this study was to determine whether accuracy training for interval judgments of stuttering might generalize to increased accuracy and/or interjudge agreement for intervals other than those used during training. Ten upper-division speech-language pathology students judged 5-s audiovisually recorded speech intervals as stuttered or nonstuttered in a series of group and single-subject experiments. Judgment accuracy was determined with respect to judgments provided previously by 10 recognized authorities on stuttering and its treatment. Training occurred within single-subject experiments that used multiple baselines across speakers and repeated generalization probes to assess training effects. Results showed that judgment accuracy tended to increase after training for speakers used during the training process as well as for unfamiliar speakers. Results also replicated previous findings of slight increases in interjudge and intrajudge agreement after interval-judgment training. The implications of these results for developing a valid and reliable stuttering measurement system are discussed.

Identifying the onset and offset of stuttering events

This study was designed to investigate the apparent contradiction between recent reports of physiological and interpersonal research on stuttering that claim or imply high agreement levels, and studies of stuttering judgment agreement itself that report much lower agreement levels. Four experienced stuttering researchers in one university department used laser videodisks of spontaneous speech, from persons whose stuttering could be described as mild to severe, to locate the precise onset and offset of individual stuttering events. Results showed a series of interjudge disagreements that raise serious questions about the reliability and validity of stuttering event onset and offset judgments. These results highlight the potentially poor reliability of a measurement procedure that is currently widespread in stuttering research. At the same time, they have isolated some few highly agreed stuttering events that might serve as the basis for the further development of either event-based or interval-based judgment procedures.

Stuttering includes both within-word and between-word disfluencies

A growing practice divides stuttered disfluencies from normal disfluencies by defining the former as "within-word" and the latter as "between-word." After reviewing the available logical and empirical evidence, this note concludes that the unstated implications of a strong form of this definition (that no between-word disfluencies are stuttering and that all within-word disfluencies are stuttering) cannot currently be supported. A weaker form of this definition might prove useful for the definition and measurement of stuttering, but only if such a definition can be both internally consistent and consistent with available clinical and empirical information.

Judgments of stuttered and nonstuttered intervals by recognized authorities in stuttering research

The study reported in this paper gathered judgments of stuttering on brief (5.0-sec) audiovisual speech samples taken from six adults who stuttered. Judgments were made by 10 highly experienced authorities on stuttering treatment and research, located in seven different universities or clinical research centers. Results showed considerable agreement between pairs of judges working in the same center, but large and potentially fundamental differences were identified in the amount of stuttering recorded in different centers. Approximately 40% of the 5.0-sec speech intervals used in this study were assigned the same judgment, either Stuttered or Nonstuttered, by all judges on two judgment occasions. The possibility that these intervals may serve as a core for establishing an across-center standard for behavioral judgments of stuttering is discussed.

Time-interval measurement of stuttering: effects of training with highly agreed or poorly agreed exemplars

This study required six groups of judges, three experimental groups and three control groups (all n = 5), to categorize consecutive 5.0-sec speech intervals as Stuttered or Nonstuttered on four judgment occasions. Between the second and third occasions, each experimental group was trained to categorize correctly one of three sets of speech intervals: agreed intervals, which had been unanimously prejudged to be Stuttered or Nonstuttered; disagreed intervals, which had been prejudged to be Stuttered by approximately half of a large group of judges; or randomly selected intervals, including both agreed and disagreed intervals. Results replicated and extended an earlier finding of improved interjudge agreement for judges trained with highly agreed intervals (Ingham, Cordes, & Gow, 1993): Training with highly agreed intervals was shown to be more effective than equivalent exposure to those intervals without feedback, and training with highly agreed intervals was shown to be more effective than training with, or exposure to, poorly agreed or randomly selected intervals.

Activation and serine phosphorylation of the p56lck protein tyrosine kinase in response to antigen receptor cross-linking in B lymphocytes

We show that cross-linking the B cell AgR with anti-Ig Abs activates p56lck (Lck) in both the immature B cell line WEHI-231 and mature resting B cells from mouse spleen. Anti-Ig-stimulated Lck activity peaked after 1 to 2 min, but remained elevated for at least 15 min. Consistent with the proposed role for src family tyrosine kinases in AgR signaling, we found that Lck could phosphorylate the cytoplasmic tails of the Ig-alpha and Ig-beta components of the B cell AgR in vitro. Lck phosphorylated both of the tyrosines in the Ig-beta AgR homology motif and one of the two tyrosines in the Ig-alpha AgR homology motif. Finally, we show that AgR ligation in B cells caused a significant portion of the Lck to migrate with an apparent molecular mass of 60 kDa on SDS-PAGE gels. Conversion of p56lck to p60lck was maximal at 5 to 15 min, at which times Lck activity in the cells was decreasing. This Lck "band shift" has been observed previously in activated T cells and correlates with phosphorylation of Lck at serine 59. We show that the 60-kDa form of Lck induced by AgR cross-linking in B cells is also phosphorylated at serine 59. Phosphorylation of Lck at this site in vitro decreases its activity. Thus, in B cells, AgR cross-linking activates Lck and subsequently activates a kinase that phosphorylates Lck at serine 59, a potential negative regulatory site.

Activation and serine phosphorylation of the p56lck protein tyrosine kinase in response to antigen receptor cross-linking in B lymphocytes

We show that cross-linking the B cell AgR with anti-Ig Abs activates p56lck (Lck) in both the immature B cell line WEHI-231 and mature resting B cells from mouse spleen. Anti-Ig-stimulated Lck activity peaked after 1 to 2 min, but remained elevated for at least 15 min. Consistent with the proposed role for src family tyrosine kinases in AgR signaling, we found that Lck could phosphorylate the cytoplasmic tails of the Ig-alpha and Ig-beta components of the B cell AgR in vitro. Lck phosphorylated both of the tyrosines in the Ig-beta AgR homology motif and one of the two tyrosines in the Ig-alpha AgR homology motif. Finally, we show that AgR ligation in B cells caused a significant portion of the Lck to migrate with an apparent molecular mass of 60 kDa on SDS-PAGE gels. Conversion of p56lck to p60lck was maximal at 5 to 15 min, at which times Lck activity in the cells was decreasing. This Lck "band shift" has been observed previously in activated T cells and correlates with phosphorylation of Lck at serine 59. We show that the 60-kDa form of Lck induced by AgR cross-linking in B cells is also phosphorylated at serine 59. Phosphorylation of Lck at this site in vitro decreases its activity. Thus, in B cells, AgR cross-linking activates Lck and subsequently activates a kinase that phosphorylates Lck at serine 59, a potential negative regulatory site.

Time-interval measurement of stuttering: effects of interval duration

The study reported in this article used a binary forced-choice judgment procedure to investigate the effects of sample duration on observers' judgements of stuttering. Two groups of judges, differing in their previous experience with stuttering, categorized 270 speech intervals as stuttered or nonstuttered; the intervals were drawn from 30 persons who stuttered and ranged from 1 sec to 15 sec in duration. Results showed that judgments were consistently related to interval duration, with shorter intervals significantly more likely than longer intervals to be labeled nonstuttered. Interjudge agreement levels, however, were largely unaffected by the different interval durations for most speakers and for both judge groups, with the exception of the longest and shortest intervals drawn from speakers evidencing the mildest and most severe stuttering. An interval duration in the 3- to 5-sec region appeared to attract the most satisfactory level of agreement. The implications of these findings for interval-based clinical and experimental measurements of stuttering are discussed.

The reliability of observational data: II. Issues in the identification and measurement of stuttering events

Much attention has been directed recently toward the problem of measuring occurrences of stuttering with satisfactory levels of interjudge agreement. This paper reviews the prominent concepts of the stuttering event, arguing that they may be one cause of the stuttering measurement problem. The evidence that has led to concerns about the reliability of stuttering event measurements is also reviewed. Reliability and measurement issues that were discussed in the first paper of this series (Cordes, 1994) emerge as basic to the interpretation of much stuttering research, and it is argued that the stuttering measurement problem is not confined to research on stuttering judgments but actually permeates other important stuttering research areas. Some recent attempts to resolve the stuttering measurement problem are reviewed, and the implications of developing an improved measurement system for this disorder are discussed.

Stutterers' self-ratings of how natural speech sounds and feels

The efficacy of stuttering treatment has been a contentious issue in recent years. Two issues of primary concern include the treated stutterer's abnormal speech quality and the problem of continually self-monitoring fluency skills. One approach to addressing these issues is to obtain stutterers' self-ratings of speech quality and levels of speech monitoring. However, the reliability and validity of such self-ratings need to be assessed before they are suitable for use in stuttering treatment. The present study investigated one method of estimating the reliability and validity of stutterers' self-ratings of how natural their speech sounds (speech naturalness), and how natural they feel about the amount of attention they are paying to the way they are speaking (feel naturalness). Twelve adult stutterers were instructed to self-rate the speech and feel naturalness of their speech under a variety of rhythmic stimulation conditions across repeated rating occasions. With some qualifications, the results showed that stutterers were relatively consistent and valid self-raters of speech quality and levels of speech monitoring.

Purification and identification of tyrosine-phosphorylated proteins from B lymphocytes stimulated through the antigen receptor

The activation of protein tyrosine kinase (PTKs) and subsequent tyrosine phosphorylation of cellular proteins is a critical initial signal in the response of eukaryotic cells to mitogens, differentiative signals, and other stimuli. A number of PTK substrates have been identified and many of these are components of signal transduction pathways that regulate cell function. However, the majority of proteins that are tyrosine-phosphorylated in response to receptor signaling remain unidentified. As some of these unidentified PTK substrates may also be signal-transducing proteins, their identification and functional characterization is an important objective towards understanding receptor signaling. We describe the development of a comprehensive and general process for the isolation and structural characterization of tyrosine-phosphorylated proteins. The method involves enrichment by anti-phosphotyrosine affinity chromatography, electrophoretic concentration and separation, and proteolytic fragmentation of individual purified phosphoproteins. Resulting peptide fragments are separated by microbore reverse-phase high performance liquid chromatography (RP-HPLC) and a portion of the eluted peptides are subjected to electrospray-mass spectrometry (ES/MS) for accurate determination of peptide masses. Proteolytic fragmentation of a protein produces a characteristic set of peptide masses that can be used to rapidly identify the protein by searching databases containing the peptide mass "fingerprints" for all known proteins. The identity of the protein established by this method can be confirmed by sequence analysis of selected peptides. We have applied this procedure to the analysis of PTK substrates from B lymphocytes that have been stimulated through the B cell antigen receptor (BCR). Signaling by this receptor is involved in the generation of antibodies against foreign molecules (antigens). The BCR activates multiple PTKs which phosphorylate at least 30 different proteins. We have identified several of these tyrosine-phosphorylated proteins, including Syk, a PTK that is known to be tyrosine-phosphorylated in activated B cells. Thus, the procedure described here can be used to identify regulatory proteins of low abundance. The process consists of a logical succession of compatible steps that avoids pitfalls inherent to prior attempts to characterize low abundance phosphoproteins and should find wide use for the identification of tyrosine-phosphorylated proteins in other cell types.

Time-interval measurement of stuttering: systematic replication of Ingham, Cordes, and Gow (1993)

The study reported in this paper was designed to replicate and extend the results of an earlier study (Ingham, Cordes, & Gow, 1993) that investigated time-interval judgments of stuttering. Results confirmed earlier findings that interjudge agreement is higher for these interval-recording tasks than has been previously reported for event-based analyses of stuttering judgments or for time-interval analyses of event judgments. Results also confirmed an earlier finding that judges with intrajudge agreement levels of 90% or better show higher interjudge agreement than judges with lower intrajudge agreement scores. This study failed to find differences between audiovisual and audio-only judgment conditions; between relatively experienced and relatively inexperienced student judges; and, most importantly, between the judgments made, and the agreement levels achieved, by judges from two different clinical research settings. The implications of these findings for attempts to develop a reliable measurement method for stuttering are discussed.

Time-interval measurement of stuttering: modifying interjudge agreement

This paper reports the results of two experiments that investigated interval-by-interval inter- and intrajudge agreement for stuttered and nonstuttered speech intervals (4.0 sec). The first experiment demonstrated that interval-by-interval interjudge agreement could be significantly improved, and to satisfactory levels, by training judges to discriminate between experimenter-agreed intervals of stuttered and nonstuttered speech. The findings also showed that, independent of training, judges with relatively high intrajudge agreement also showed relatively higher interjudge agreement. The second experiment showed that interval-by-interval interjudge agreement was not significantly different if judges rated 4-sec speech intervals from different samples under three conditions: in random order, separated by 5-sec recording intervals; in correct order, also separated by 5-sec recording intervals; or after brief judgment signals that occurred every 4 sec during continuous samples. The implications of these findings for stuttering measurement are discussed.