Effects of reinforced directed rehearsal on expressive sign language learning by persons with mental retardation

This study used a multielement design to compare standard training (prompting and reinforcement) with and without reinforced directed rehearsal as a correction procedure in teaching expressive sign language to 10 nonverbal students with moderate to severe mental retardation. Standard training consisted of either sequential prompting or graduated guidance and 5 students were randomly assigned to each condition. Directed rehearsal involved 10 practices of the correct sign contingent on an error or no response; praise was given during directed rehearsal for cooperation and attempted signing. A stimulus control analysis revealed that only 6 of the 10 students (3 from each standard training condition) completely discriminated the trained signs within the maximum training period of 160 trials (3 of the 4 students who failed the stimulus control test were hearing impaired; the remaining 6 who showed stimulus control were not). Using only these six students' data, we found that directed rehearsal increased: (a) accuracy (percent correct), (b) speed of learning (required fewer trials to criterion), (c) efficiency (decreased total instruction time), and (d) generalization (across trainers, objects, and settings). There were no obvious interactions between directed rehearsal and the type of prompting strategy employed. Very little agitated behavior occurred in any of the sessions, and a treatment acceptability survey indicated that 10 of 14 direct-care staff and the trainers in this study preferred corrective directed rehearsal (as used in this study) over standard training alone. The results indicate that directed rehearsal may be a valuable adjunct to sign language training with nonverbal students with mental retardation.     

The perception of shrinking in apparent motion

Apparent motion was produced using two triangular patterns of different sizes, each exposed for 100 msec, with a 50-msec interstimulus interval and 200-msec recycle interval. The triangles were aligned either on center or on the midpoints of the bases. Experiment 1, filled, outline, and three-dot triangles were viewed over four backgrounds: a blank illuminated field, and texture gradients constructed from horizontal lines, perspective lines, or a combination of these (full texture). In Experiment 2, outline and dot triangles were presented in one of three orientations: base down, base right, and base up over a blank background. Subjects made two forced-choice responses: apparent size was categorized as shrinking or not shrinking, and apparent motion was categorized as motion in depth or motion in a fixed frontal plane. The type of alignment was the major determiner of responses. When the midpoints of the base were aligned, the predominant response described a shrinking object in a fixed-position in depth. When the centers were aligned, the predominant response described an object of constant size moving in depth.     

Size-distance invariance: Kinetic invariance is different from static invariance

The static form of the size-distance invariance hypothesis asserts that a given proximal stimulus size (visual angle) determines a unique and constant ratio of perceived-object size to perceived object distance. A proposed kinetic invariance hypothesis asserts that a changing proximal stimulus size (an expanding or contracting solid visual angle) produces a constant perceived size and a changing perceived distance such that the instantaneous ratio of perceived size to perceived distance is determined by the instantaneous value of visual angle. The kinetic invariance hypothesis requires a new concept, an operating constraint, to mediate between the proximal expansion or contraction pattern and the perception of rigid object motion in depth. As a consequence of the operating constraint, expansion and contraction patterns are automatically represented in consciousness as rigid objects. In certain static situations, the operation of this constraint produces the anomalous perceived-size-perceived-distance relations called the size-distance paradox.     

Letter memory loads change more than visual-field advantage: Interhemispheric coupling effects

A derivation from Denenberg's (Denenberg, 1980. American Journal of Physiology, 238, R3-R13) model of brain organization is that significant correlations between left-hemisphere (LH) and right-hemisphere (RH) measures indicate that the hemispheres are coupled together in a general system. Two formally similar visual-field (VF) reaction-time (RT) tasks, one a LH-right (R) VF and the other a RH-left (L) VF advantage task, were performed by 30 female and 30 male right-handers under single-task (zero load) and dual task (three or six consonants in memory) conditions. Expected letter load effects upon VF performances were obtained. Particularly for RT variability, correlations of measures lateralized to different hemispheres (i.e., LVF-RVF, LH and RH tasks) increased linearly as load increased, while correlations of measures lateralized to the same hemisphere (i.e., two LH tasks) did not. Bihemispheric cortical activation may play a role in this general system coupling caused by complexity or load. Females demonstrated greater interhemispheric coupling.     

The Prevention of Cigarette Smoking in Children: A Comparison of Four Strategies1

Adolescent cigarette smoking remains a serious public health problem. Recent preventive efforts have concentrated on the social influences which encourage smoking onset. They appear more effective than earlier efforts which considered primarily the long term health risks of smoking. In spite of this progress, it has not been possible to identify the necessary or sufficient conditions for the reported treatment effects due largely to issues of research design. We report data from two consecutive studies designed to address this problem. In each study, four treatment strategies were compared for their effectiveness in deterring smoking onset and in minimizing future smoking levels. In the second study, an untreated reference condition was also included. Approximately 7000 students participated in the two studies. Baseline data were gathered in September of the seventh-grade year, interventions were conducted during the full year, and post-test and followup data were collected annually beginning in May of that year. These data suggest that a program which teaches specific skills to resist social pressures to begin smoking and which teaches students about the short term physiological consequences of smoking is more effective than a program which concentrates on long term health consequences. Perhaps most important, the use of same-age peer leaders as teachers appears to be a necessary condition for successful use of this intervention program.     

Regional cerebral blood flow patterns during verbal and nonverbal auditory activation

Current views of the relationship between audition and cerebral function suggest that increases in regional cerebral blood flow (rCBF) would occur in the superior, mid, and posterior portions of the temporal lobes, and that these changes would be more lateralized to the left hemisphere for a verbal than a nonverbal auditory task. We measured rCBF using the xenon inhalation technique in a group of healthy subjects during three conditions: (1) resting baseline, (2) auditory verbal activation (listening for word meaning), and (3) auditory nonverbal activation (listening for reduction of intensity in a series of noise bursts). Both verbal and nonverbal conditions produced highly significant increases in rCBF over the left posterior Sylvian region with a trend for verbal activation to evoke a wider area of flow increase than the nonverbal task.     

Foundationalism with infinite regresses of probabilistic support

There is a long-standing debate in epistemology on the structure of justification. Some recent work in formal epistemology promises to shed some new light on that debate. I have in mind here some recent work by David Atkinson and Jeanne Peijnenburg, hereafter “A&P”, on infinite regresses of probabilistic support. A&P show that there are probability distributions defined over an infinite set of propositions {\(p_{1}, p_{2}, p_{3}, {\ldots }, p_{n}, {\ldots }\}\) such that (i) \(p_{i}\) is probabilistically supported by \(p_{i+1}\) for all i and (ii) \(p_{1}\) has a high probability. Let this result be “APR” (short for “A&P’s Result”). A&P oftentimes write as though they believe that APR runs counter to foundationalism. This makes sense, since there is some prima facie plausibility in the idea that APR runs counter to foundationalism, and since some prominent foundationalists argue for theses inconsistent with APR. I argue, though, that in fact APR does not run counter to foundationalism. I further argue that there is a place in foundationalism for infinite regresses of probabilistic support.