AN ANALYSIS OF A GROUP TEACHING PROCEDURE FOR PERSONS WITH DEVELOPMENTAL DISABILITIES

This study evaluated whether a concurrent group teaching procedure, in which all students respond simultaneously, could be used for persons with moderate or severe mental retardation. The teaching procedure used was the Task Demonstration Model, a program based on stimulus-control research and the fading techniques of behavioral psychology. Three teachers and three groups of students participated. Results showed that the teachers increased their rates of questions and instructions, positive feedback, and use of functional materials, but they reduced their rate of prompts to almost zero. Students increased their percentage and rate of correct responding as well as their engaged time. In addition, maladaptive responding, for which there were never any direct consequences, decreased from 45% to 10% for 8 of the 14 students. Results are discussed primarily in two areas: (a) changing stimulus control from teacher prompts to critical elements of the items being taught, and (b) reasons for the reduction of maladaptive behavior for 8 of the subjects.     

Detectability of duration and intensity increments in melody tones: A partial connection between music perception and performance

Two experiments demonstrate positional variation in the relative detectability of, respectively, local temporal and dynamic perturbations in an isochronous and isodynamic sequence of melody tones, played on a computer-controlled piano. This variation may reflect listeners’ expectations of expressive performance microstructure (thetop-down hypothesis), or it may be due to psychoacoustic (pitch-related) stimulus factors (thebottom-up hypothesis). Percent correct scores for increments in tone duration correlated significantly with the average timing profile of pianists’ expressive performances of the music, as predicted specifically by the top-down hypothesis. For intensity increments, the analogous perception-performance correlation was weak and the bottom-up factors of relative pitch height and/or direction of pitch change accounted for some of the perceptual variation. Subjects’ musical training increased overall detection accuracy but did not affect the positional variation in accuracy scores in either experiment. These results are consistent with the top-down hypothesis for timing, but they favor the bottom-up hypothesis for dynamics. The perception-performance correlation for timing may also be viewed as being due to complex stimulus properties such as tonal motion and tension/relaxation that influence performers and listeners in similar ways.     

Single formant contrast in vowel identification

Subjects rated ambiguous steady-state vowels from a continuum with respect to the categories/i/ and /I/ (Experiment 1) or/ε/ and/ae/ (Experiment 2). Each target was preceded, .35 sec earlier, by one of the following precursors: (1) one endpoint from the target continuum, (2) the other endpoint, (3) the isolated first formant (F1) from (1), (4) the isolated F1 from (2), or (5), a hissing noise. Although (3) and (4) did not sound like they came from the target continuum, they produced reliable contrast in both experiments. In the /i/-/I/ experiment, contrast was as powerful from single formants as from the full vowels. These results suggest a sensory, rather than a judgmental, basis for the vowel contrast effects obtained.     

REDUCING AGGRESSIVE AND SELF-INJURIOUS BEHAVIOR OF INSTITUTIONALIZED RETARDED CHILDREN THROUGH REINFORCEMENT OF OTHER BEHAVIORS1

Aggressive and self-injurious behaviors of four retarded children were reduced by combining various techniques with the differential reinforcement of other behaviors (DRO). In one study, aggressive responses of a severely retarded child were reduced when DRO was combined with a 30-sec timeout. In a second study, various aggressive classroom behaviors were reduced when the child was told “no” for an inappropriate response but earned puzzle pieces for periods of time when inappropriate responses did not occur. Exchangeable tokens were given to a third subject for every 15 min in which aggressive responding did not occur, while each inappropriate response resulted in the loss of all tokens accrued. Responding was decreased to a level far below baseline. For a fourth child, self-injurious responses were followed by “no”, and intervals of time in which no self-injurious responding occurred earned candy. The rate of this behavior reduced significantly. In each case, the DRO procedure combined with the other techniques proved to be manageable for the teacher and successful in reducing the inappropriate behavior.     

AN EVALUATION OF GENTLE TEACHING AND VISUAL SCREENING IN THE REDUCTION OF STEREOTYPY

Gentle teaching and visual screening techniques have been used to control severe behavior problems in persons with mental retardation. An alternating treatments design was used to compare gentle teaching, visual screening, and a task-training condition in the reduction of the high-level stereotypy of 3 persons with mental retardation. Following a baseline phase, a task-training condition using standard behavioral techniques was implemented to establish the effects of training the subjects on the tasks. Results showed a modest decrease in stereotypy. This phase was followed by an alternating treatments phase in which visual screening, gentle teaching, and baseline conditions were compared. Both procedures were superior to the control condition in reducing stereotypic behavior, with visual screening being more effective than gentle teaching. When compared with data from the prior phase, gentle teaching was found to be more effective than task training for 2 subjects but less effective for the 3rd, whose stereotypy increased during gentle teaching. Two succeeding phases in which visual screening was implemented across two and then all three daily conditions reduced stereotypy further to near-zero levels. An additional phase with 1 subject demonstrated that the treatment effects of visual screening were easily replicated across therapists. Mixed and idiosyncratic changes in collateral behaviors occurred. For example, “bonding,” the goal of gentle teaching, occurred at the same low levels under both treatments, contrary to the predictions of gentle teaching's proponents. The results indicate that gentle teaching may not be the universal treatment of choice for stereotypy its proponents suggest, and that it requires further empirical evaluation.     

Compensation for subliminal timing perturbations in perceptual-motor synchronization

 It is sometimes assumed that limits of temporal discrimination established in psychophysical tasks constrain the timing information available for the control of action. Results from the five perceptual-motor synchronization experiments presented here argue against this assumption. Experiment 1 demonstrates that subliminal (0.8–2%) local changes in interval duration in an otherwise isochronous auditory sequence are rapidly compensated for in the timing of synchronized finger tapping. If this compensation is based on perception of the highly variable synchronization error (SE) rather than of the local change in stimulus period, then it could be based solely on SEs that exceed the temporal order threshold. However, that hypothesis is ruled out by additional analyses of Exp. 1 and the results of Exp. 2, a combined synchronization and temporal order judgment task. Experiments 3–5 further show that three factors that affect the detectability of local deviations from stimulus isochrony do not inhibit effective compensation for such deviations in synchronized tapping. Experiment 5, a combined synchronization and detection task, shows directly that compensation for timing perturbations does not depend on explicit detection. Overall, the results suggest that the automatic processes involved in the temporal control of action have access to more accurate timing information than do the conscious decision processes of auditory temporal judgment. Received: 19 November 1998 / Accepted: 18 March 1999     

Sensorimotor synchronization: A review of the tapping literature

Sensorimotor synchronization (SMS), the rhythmic coordination of perception and action, occurs in many contexts, but most conspicuously in music performance and dance. In the laboratory, it is most often studied in the form of finger tapping to a sequence of auditory stimuli. This review summarizes theories and empirical findings obtained with the tapping task. Its eight sections deal with the role of intention, rate limits, the negative mean asynchrony, variability, models of error correction, perturbation studies, neural correlates of SMS, and SMS in musical contexts. The central theoretical issue is considered to be how best to characterize the perceptual information and the internal processes that enable people to achieve and maintain SMS. Recent research suggests that SMS is controlled jointly by two error correction processes (phase correction and period correction) that differ in their degrees of cognitive control and may be associated with different brain circuits. They exemplify the general distinction between subconscious mechanisms of action regulation and conscious processes involved in perceptual judgment and action planning.