Effects of category diversity on learning,memory, and generalization

In this study, we examined the effect of within-category diversity on people's ability to learn perceptual categories, their inclination to generalize categories to novel items, and their ability to distinguish new items from old. After learning to distinguish a control category from an experimental category that was either clustered or diverse, participants performed a test of category generalization or old-new recognition. Diversity made learning more difficult, increased generalization to novel items outside the range of training items, and made it difficult to distinguish such novel items from familiar ones. Regression analyses using the generalized context model suggested that the results could be explained in terms of similarities between old and new items combined with a rescaling of the similarity space that varied according to the diversity of the training items. Participants who learned the diverse category were less sensitive to psychological distance than were the participants who learned a more clustered category.     

Operant psychology goes to the fair: Marian and Keller Breland in the popular press, 1947-1966

Marian and Keller Breland pioneered the application of operant psychology to commercial animal training during the 1940s and 1950s. The Brelands' story is relatively unknown in the history of behavior analysis. Using information from the Breland-Bailey papers, this paper describes the development and activities of Animal Behavior Enterprises (ABE), the Brelands' animal training business. We also review popular press coverage of the Brelands between 1947 and 1966 to investigate the level of public exposure to ABE-trained animals and to the principles and methods of operant psychology. An examination of 308 popular print articles featuring the Brelands indicates that there was public exposure of behavior analysis through the popular press coverage of ABE-trained animals. Furthermore, the expansion of operant methods to the marine mammal and bird training industries can be linked to the Brelands' mass media exposure.     

Newborn screening for fragile X syndrome

Newborn screening for fragile X syndrome (FXS) is technically possible, and in the relatively near future accurate and inexpensive screening technologies are likely to be available. When that happens, will America's public health system adopt newborn screening for fragile X syndrome? This article addresses this issue by first placing screening for FXS in the context of the history and current status of newborn screening policy and practice. Lack of a proven medical treatment may stand as a barrier to newborn screening, but strong arguments can be made that early intervention provides important services for identified newborns and their families. Furthermore, other arguments could be used to justify newborn screening, including informed reproductive risk, medically necessary information, and consumer demand. Fragile X syndrome is offered as a prototype for many of the issues that will face society as more genetic disorders are discovered and new technologies for screening are developed.     

ON THE EFFECTS OF NONCONTINGENT DELIVERY OF DIFFERING MAGNITUDES OF REINFORCEMENT

We conducted a parametric analysis of response suppression associated with different magnitudes of noncontingent reinforcement (NCR). Participants were 5 adults with severe or profound mental retardation who engaged in a manual response that was reinforced on variable-ratio schedules during baseline. Participants were then exposed to NCR via multielement and reversal designs. The fixed-time schedules were kept constant while the magnitude of the reinforcing stimulus was varied across three levels (low, medium, and high). Results showed that high-magnitude NCR schedules produced large and consistent reductions in response rates, medium-magnitude schedules produced less consistent and smaller reductions, and low-magnitude schedules produced little or no effect on responding. These results suggest that (a) NCR affects responding by altering an establishing operation (i.e., attenuating a deprivation state) rather than through extinction, and (b) magnitude of reinforcement is an important variable in determining the effectiveness of NCR.     

Adaptive behavior of retarded,slow-learner,and average intelligence children

Scores on the WISC-R and the AAMD Adaptive Behavior Scale, Part I, Public School Version, were obtained for 94 elementary school children referred for psychological services in a southeastern rural area. Some of the adaptive behavior scores differentiated among children classified as EMR, slow-learners, or average intelligence. Some of the domain subscores of the ABS seem of questionable validity and reliability.     

STIMULUS OVERSELECTIVITY IN LEARNING DISABLED CHILDREN

Stimulus overselectivity, a phenomenon exhibited by autistic and institutionalized retarded individuals, was examined in mildly handicapped and nonhandicapped public school children. Subjects were 16 young, educable mentally retarded, 16 learning disabled, 15 nonhandicapped first- and second-graders, and 16 older, educable retarded students. The children were trained on a 3-component visual discrimination task and then tested on individual elements to determine which element or elements were controlling subject responses. Nine of the young educable mentally retarded children and eight of the learning disabled students showed some overselectivity. The majority of overselective retarded children were controlled by only one of the three components of the training cue, whereas the majority of the overselective learning disabled children responded to the discrimination task on the basis of two of the three components. No overselectivity was exhibited by the nonhandicapped students. All three cue components were also functional in controlling the responding of 14 of the 16 older retarded students, but two children were under the control of only one cue. The research indicated that in terms of overselectivity, learning disabled children respond more like young, mildly retarded children than they do like nonhandicapped ones. The demonstration of stimulus overselectivity in a sizable portion of a learning disabled sample may have implications for a more empirically based approach to this handicapped population.     

THE MODIFICATION OF LEISURE BEHAVIOR IN A HALF-WAY HOUSE FOR RETARDED WOMEN1

A multi-element baseline design combined with a multiple-baseline design, was used to investigate the effect of availability of materials, prizes for participation, and instruction on the leisure behavior of 14 mentally retarded women in a half-way house. A leisure program was conducted on weekday evenings, during which residents could choose to participate in any of six activities offered: puzzles, card games, clay, painting, weaving, and rug making. It was found that instruction in weaving and rug making significantly increased the percentage of residents participating in these activities, and that following instruction, prizes were not necessary to maintain high levels of participation. In contrast, prizes were more effective than mere availability of materials in maintaining participation in the other activities.     

Effects of training, prompting, and self-monitoring on staff behavior in a classroom for students with disabilities

This study extended the limited research on the utility of tactile prompts and examined the effects of a treatment package on implementation of a token economy by instructional assistants in a classroom for students with disabilities. During baseline, we measured how accurately the assistants implemented a classroom token economy based on the routine training they had received through the school system. Baseline was followed by brief in-service training, which resulted in no improvement of token-economy implementation for recently hired instructional assistants. A treatment package of prompting and self-monitoring with accuracy feedback was then introduced as a multiple baseline design across behaviors. The treatment package was successfully faded to a more manageable self-monitoring intervention. Results showed visually significant improvements for all participants during observation sessions.     

Transcranial magnetic stimulation as a tool for cognitive studies

Transcranial Magnetic Stimulation (TMS) is a tool for the non-invasive stimulation of the human brain. It allows the activation of arbitrary sites of the superficial cortex and, combined with other brain-imaging techniques such as EEG, PET, and fMRI, it can be used to evaluate cortical excitability and connectivity. This is of major importance in, for example, the study of cognitive processes such as language, learning, memory and self-representation, which are thought to be represented in multiple brain areas. The mechanisms of action of TMS are known on a basic level, but its effect on the activation state of brain tissue is still poorly understood. Clinical applications of TMS have also been proposed and guidelines for its safe use drafted.