Stimulation of spinach (Spinacia oleracea) chloroplast fructose-1,6-bisphosphatase by mercuric ions.

Chloroplast fructose-1,6-bisphosphatase can exist in an active reduced form or a less active oxidised form. Oxidised fructose bisphosphatase from spinach (Spinacia oleracea) could be stimulated up to many hundred-fold by 0.1 mM HgCl2 whereas fructose bisphosphatases from rabbit, yeast, a non-chloroplast enzyme from spinach and the reduced chloroplast enzyme were only inhibited by HgCl2. Stimulation of the enzyme was maximal at pH 8.0 and low magnesium concentrations where the oxidised enzyme normally has little activity.

Control of children's stuttering with response-contingent time-out: behavioral, perceptual, and acoustic data.

Many stuttering treatments incorporate contingencies for stuttering that are thought to contribute to treatment effectiveness. One contingency used in a number of treatment programs for children is time-out (TO) from speaking. However, although TO has been shown to control stuttering in adults there are no clear demonstrations of this effect in children. One aim of the present study was to demonstrate in the laboratory that TO reduces stuttering in children. Three school-age children spoke in a single-subject ABA experiment. In the B phase, a red light was illuminated for 5 seconds when the subject stuttered, during which time the subject stopped talking. Two of the three children showed clear reductions in stuttering in response to TO. The second aim of the study was to detect whether the children who responded to To adopted an unusual speech pattern in order to control their stuttering. Listeners did not detect any differences between the perceptually stutter-free speech of baseline conditions and that of TO conditions, and a subsequent acoustic analysis revealed a reduction in the variability of vowel duration during TO in one subject and no changes in the other. The theoretical and clinical implications of the findings are discussed.

Interjudge agreement in videofluoroscopic studies of swallowing.

Videofluoroscopic swallowing examinations of 3 patients with dysphagia were reviewed independently by 10 speech-language pathologists. Prior to viewing each video, clinicians were provided with information about the patient's history, the results of a bedside swallow examination, and oral-facial and oral motor control examinations. Clinicians completed a swallowing observation protocol as they viewed each video. They then recommended, from a list of treatment strategies, intervention techniques that would be most appropriate for each patient. Interjudge agreement was calculated by determining how many clinicians observed a given swallowing event or deficit, and how many recommended a given treatment strategy. Results suggest that the level of interjudge agreement for videofluoroscopic evaluations is not encouragingly high.

Effects of distance on vocal intensity.

The vocal response of speakers to change of distance from a listener is in dispute. Warren (1968) found that speakers obeyed the inverse square law when compensating for distance changes; that is, they decreased their vocal intensity by 6 dB when distance was halved. However, speakers in a study of Johnson, Pick, Siegel, Cicciarelli, and Garber (1981) changed their vocal intensity by much less than 6 dB. This study was an attempt to reconcile the conflicting results and to gain better understanding of what people know implicitly about the effects of distance on intensity. Speakers in the present study significantly changed their vocal intensity to compensate for changes in distance, but by a maximum of 2.46 dB. Possible reasons for the different results are discussed.

Language acquisition after mutism: a longitudinal case study of autism.

This longitudinal case study challenges the assumption that individuals with autism who have severely restricted speech and language skills have a poor prognosis for further development of expressive oral language. The study follows the development of a woman with autism from mutism at age 10 to acquisition of a range of spoken and written language skills at age 26. The intervention in which the woman participated and her skills pre- and post-intervention and at two follow-up assessments are documented. The results support the hypotheses that speech and language development may proceed after mutism associated with limited verbal imitation and phoneme production skills, that some skills may plateau or decline, and that both spoken and written language may become viable forms of communication.

Modifications in sign under conditions of impeded visibility.

This study investigated the effects of reduced visibility on the distance of signing hands from the bodies of adult signers who are deaf and on their rates of sign production. Subjects were videotaped as they signed with partners in each of three experimental conditions: unimpeded, moderately impeded, and severely impeded visibility. Visual impedance was created by placing screens between signing partners. The distance of a hand from the body, in terms of lateral, vertical, and forward-depth dimensions, was determined from digitized measurements of single video frames randomly selected from those in which the subject was actively signing. Sign rate was calculated as the number of signs produced in a given segment of time. Signs produced in the severely impeded visibility condition were found to be made at a slower rate and with a mean hand position further forward and vertically higher than signs produced in the unimpeded visibility condition.

The effects of auditory and visual interference on speech and sign.

Hearing adults produced signed and spoken monologues under conditions of quiet or 80 dB SPL of noise and with their vision unobstructed or obstructed. Their signs were videotaped and a random sample of 24 frames was analyzed in each condition through a computer program that determined the overall distance of the hand from a marker placed on the signer's torso. Vocal intensity was digitized from the tape recordings and analyzed by computer for 1 min of continuous speech in each condition. The visual obstruction had no effect either on the distance of the signs or on the vocal intensity of their speech. The subjects increased vocal intensity by about 55% when the noise was introduced (the usual Lombard effect), but the noise had no effect on the distance of the signs. Sign performance was not influenced by visual feedback, and sign and speech were independent communication systems, even in bilingual speaking and signing subjects.

Imitation of intonation by infants.

Children between 9 and 12 months of age were studied to determine if they would spontaneously imitate either the average fundamental frequency or the fundamental frequency contour of their speaking partners. In the first experiment, children were recorded at home as they interacted with their fathers and mothers. Acoustic analyses failed to reveal any tendency on the part of the infants to adjust vocal pitch, amplitude, or duration to those of their speaking partners. In a second experiment, children were recorded while interacting with their parents in a laboratory setting. Again, there were no indications that the children imitated the vocal patterns of their speaking partners.

Inhibiting the Lombard effect.

The Lombard effect is the tendency to increase one's vocal intensity in noise. The present study reports three experiments that test the robustness of the Lombard effect when speakers are given instructions and training with visual feedback to help suppress it. The Lombard effect was found to be extremely stable and robust. Instructions alone had little influence on the response to the noise among untrained speakers. When visual feedback correlated with vocal intensity was presented, however, subjects could inhibit the Lombard response. Furthermore, the inhibition remained after the visual feedback was removed. The data are interpreted as indicating that the Lombard response is largely automatic and not ordinarily under volitional control. When subjects do learn to suppress the effect, they seem to do so by changing overall vocal level rather than their specific response to the noise.

The limits of science in communication disorders.

Science is a powerful tool when it addresses the kinds of questions it was designed to answer, but there are also important questions in communication disorders that fall outside the limits of science. Three such areas are discussed: Questions concerning social and personal values, questions that call for logical rather than scientific endeavors, and questions that should not be posed because we already know the answers and would not be influenced by contrary findings.

Group designs in clinical research.

Single-subject research designs, with their concentration on the individual subject over extended time durations, are similar in form to the design of therapy and have been represented as the best, if not the only, appropriate method for carrying out clinical research. Despite the similarity between single-subject research sessions and clinical sessions, it is argued that such designs are not intrinsically more appropriate than group designs for clinical research. Single-subject and group research strategies are alternative and often competing approaches to the same research question, and the choice resides as much in the predilections of the researcher as in any intrinsic advantage in one or the other research strategy.

Theory and science in communication disorders.

The role of theory and of science for communication disorders is discussed. It is argued that communication disorders is a unique discipline, committed to the understanding and remediation of disordered communication, but that it is also fully invested in the theories and paradigms that inform all of behavioral science, and so it is inappropriate to expect it to generate its own theories. Theory contributes to research and to therapy in communication disorders, and we discuss the ways in which our discipline can make rational use of theory for both enterprises.

Communication skills of elderly adults.

The communication performance of young and elderly adults was studied in dyads that were either homogeneous or heterogeneous for age. The members of each dyad were given identical matrix boards and sets of objects and were instructed to place the objects on the boards in precisely the same arrangement. The partners could see each other, but not the other's test materials. The elderly subjects were between 58 and 81 yr old, and were living independently. The young subjects were college students. There were 10 dyads consisting of pairs of older persons, 9 dyads with only young persons, and 9 dyads that involved an old and a young subject. Different subjects were used in the three groups. The groups did not differ in their accuracy or the time required to complete the task, in contrast to suggestions that the elderly communicate slowly and ineffectually. There were significantly more meta-comments in the old-young group than in the other groups; that is, in the mixed dyads, the partners commented more about the task and strategies for dealing with it than in the homogeneous pairs.

Auditory stimulation, rhythm, and stuttering.

In a previous experiment, Martin, Siegel, Johnson, and Haroldson (1984) found that stutterers reduced their stuttering under amplified sidetone, but only if the amplified sidetone condition had been preceded by a condition of speaking in noise. The authors speculated that when stutterers were exposed initially to loud noise and its attendant reduction in stuttering, they became "sensitized" to reduced stuttering in any subsequent condition where their auditory feedback was modified. The current experiment tested that hypothesis with 24 adult stutterers divided evenly into three groups. One group of stutterers spoke with no auditory stimulation (quiet), then while receiving 100 dB SPL white noise, and then while receiving amplified sidetone (0, +10, +20 dB SPL). A second group spoke in quiet, then while receiving amplified sidetone, and then while receiving amplified sidetone again. A third group spoke in quiet, then while receiving rhythmic stimulation, and then while receiving amplified sidetone. Relative to vocal intensity in quiet, stutterers spoke with increased vocal intensity during noise, with decreased vocal intensity during amplified sidetone, and with no significant change in vocal intensity during rhythmic stimulation. Relative to stuttering frequency in quiet, subjects spoke with decreased stuttering frequency during loud noise and during amplified sidetone, but only when the amplified sidetone was preceded by the loud noise condition. These results are discussed in terms of the "sensitization" hypothesis.

Therapy and research.

The thesis is developed that therapy and research are not necessarily the same activity and that clinicians are not necessarily researchers. Though there are commonalities between research and therapy, especially as the use of single-subject research designs has increased, using the scientific method to guide therapy is not the same as doing science. The requirements of good therapy and good research are often different in critical ways. Both research and therapy are important to the vitality of the profession, and the profession is strengthened when the differences are acknowledged.