Analysis of discriminative control by social behavioral stimuli

Visual discriminative control of the behavior of one rat by the behavior of another was studied in a two-compartment chamber. Each rat's compartment had a food cup and two response keys arranged vertically next to the clear partition that separated the two rats. Illumination of the leader's key lights signaled a “search” period when a response by the leader on the unsignaled and randomly selected correct key for that trial illuminated the follower's keys. Then, a response by the follower on the corresponding key was reinforced, or a response on the incorrect key terminated the trial without reinforcement. Accuracy of following the leader increased to 85% within 15 sessions. Blocking the view of the leader reduced accuracy but not to chance levels. Apparent control by visual behavioral stimuli was also affected by auditory stimuli and a correction procedure. When white noise eliminated auditory cues, social learning was not acquired as fast nor as completely. A reductionistic position holds that behavioral stimuli are the same as nonsocial stimuli; however, that does not mean that they do not require any separate treatment. Behavioral stimuli are usually more variable than nonsocial stimuli, and further study is required to disentangle behavioral and nonsocial contributions to the stimulus control of social interactions.     

SOME EFFECTS OF REINFORCEMENT SCHEDULES IN TEACHING PICTURE NAMES TO RETARDED CHILDREN1

The effects of several different schedules of primary reinforcement were compared in a picture-naming task with retarded children. In Experiment I, number of correct responses and learning rate were higher under fixed-ratio schedules than under continuous reinforcement. In Experiment II, number of correct responses and learning rate tended to be greater under intermediate than under low or high fixed-ratio schedules. In Experiment III, number of correct responses was higher under interlocking schedules, in which the response requirement increased with time following the previous reinforcement, than under comparable fixed-ratio schedules. Learning rates were generally low and, perhaps because of this, not very different under the two types of schedules in this experiment. Accuracy (i.e., proportion of trials on which correct responses occurred) was typically high and insensitive to variations in schedule and schedule parameter throughout each experiment.     

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.     

Nonhumans have not yet shown stimulus equivalence

Recently, two published articles have reported finding stimulus equivalence in nonhumans. One suggested that equivalence was due to the mediation of names. The procedure used trained all components of all tested relations. Because nothing was derived, the defining characteristics of equivalence were not achieved. In the second study a definition of equivalence was proposed that fails to distinguish functional stimulus classes from equivalence classes. The resulting data are not clearly relevant to stimulus equivalence in Sidman's sense of the term. Stimulus equivalence has not yet been shown in nonhumans.     

TEACHING MENTALLY RETARDED ADULTS TO TIME-MANAGE IN A VOCATIONAL SETTING

Three retarded adults who had minimal ability to tell time were trained to “time-manage.” Each was given a card with clock face representations on which the hands of the clock were drawn, representing each trainee's assigned lunch and break times. Instruction was given before work to perform each of the required behaviors when the “real” clock matched the clock faces. Praise was given following correct responses, and reprimands, instruction, and, in some instances, delay or omission of the scheduled activity followed incorrect responses. Pre-instruction and instructional feedback were then sequentially withdrawn. Results indicated that the package consisting of pre-instruction, instructional feedback, and picture cues was effective in producing independent time management responding. When the first two components were withdrawn, two trainees maintained high levels of correct responding. Correct responding decreased for one trainee when pre-instruction was withdrawn. Reintroduction and subsequent withdrawal of the components resulted in maintenance by this trainee. Little improvement in time-telling ability resulted.     

MULTIPLE TREATMENT INTERFERENCE IN THE ALTERNATING TREATMENTS DESIGN AS A FUNCTION OF THE INTERCOMPONENT INTERVAL LENGTH

In experimental designs requiring the administration of more than one treatment to the same subject(s), the effect of one treatment may be influenced by the effect of another treatment (Campbell & Stanley, 1963), a phenomenon known as multiple treatment interference. We conducted two studies in which multiple treatment interference in an alternating treatments design was shown to be a function of the length of the intercomponent interval (ICI) separating treatment conditions. In the first study, we evaluated the effects of four different treatments on the mouthing of a severely retarded boy. Under a 1-min ICI no consistent differential responding to treatment was obtained. Differential responding emerged when the ICI was increased from 1 min to 120 min, thus suggesting multiple treatment interference in the lack of differential responding under a 1-min changeover interval. Functional control of the nondifferential and differential responding as a function of the ICI length was replicated in a reversal phase. In the second study, we compared two treatment procedures for the disruptive noncompliant behavior of a moderately retarded boy. Multiple treatment interference (i.e., the lack of differential responding) occurred with the 1-min intercomponent interval. An increase to a 120-min ICI again resulted in differential responding. A replication of multiple treatment interference by a reversal to a short interval phase was not achieved in the second subject. Results of this study support much of the basic literature on discrimination and multiple treatment interference. Major findings of this study are twofold: Multiple treatment interference can depend on the length of the changeover interval between treatments and multiple treatment interference can take the form of a lack of differential responding to various treatments. Implications for future research are discussed.     

发展性阅读障碍的视觉拥挤效应

发展性阅读障碍的核心缺陷一直是研究者关注的焦点。近年来,国内外大量研究发现视觉加工缺陷可能是导致阅读障碍的一个重要原因,其中视觉拥挤效应与阅读障碍密切相关。本文将回顾视觉拥挤效应的概念及其理论基础、拼音文字和汉语阅读障碍者视觉拥挤效应的相关研究,提出汉语阅读障碍视觉拥挤效应研究的未来发展方向,以便更好地了解汉语阅读障碍与视觉拥挤效应之间的关系。     

Sub-threshold cuing: Saccadic responses to low-contrast,peripheral, transient visual landmark cues

Dorsal stream visual encoding was studied in three experiments, by examining effects of peripheral landmark cues on eye movements. Stimulus features and task structure were tailored to physiological and functional characterisations of the dorsal visual stream. Sub-discriminable peripheral stimuli served as landmark cue stimuli. In Experiments 1 and 2, orienting behaviour in response to cues and targets differed for participants with relatively low and relatively high peripheral contrast thresholds. In Experiment 1, low, but not high-threshold participants oriented towards landmark cues that could not be discriminated consciously. However, in Experiment 3, high-, but not low-threshold participants oriented towards near threshold cues. Hence, under appropriate conditions both groups of participants oriented in response to brief, low-contrast, peripheral information. We propose that landmark cueing may provide a useful tool for measuring individual differences in dorsal stream processing and dynamic aspects of visual functioning and awareness.