Stimulus overselectivity is said to occur when behavior is under the control of a restricted set of stimuli from a stimulus complex. Three studies investigated the effects of specific multiple-stimulus training histories upon the overselective responding of normal preschool children. In Experiment 1, eight children 3 to 5 years of age, were trained to discriminate forms presented on cards. Each form was labelled with a nonsense syllable, and each card (multiple stimulus) consisted of two forms. A time-delay training procedure was used. Four subjects were trained using Concurrent training in which two of the three S- response choices contained components of the S+. Four subjects were trained using Sequential training in which the choices did not contain S+ components, but S+s were trained in order such that one component of a previously- trained S+ was present in the next S+. Subjects trained using Concurrent training acquired the discriminations in fewer trials, and had fewer errors during training. However, they responded to single components at chance level, whereas subjects trained using Sequential training recognized components and were able to recombine them into novel combinations. Experiment 2 was designed to investigate the effects of interspersing component probes among review trials of previously learned S+s that contained those components. Responses of two subjects to components were probed with interspersed review trials. Subjects with a Sequential training history demonstrated higher levels of correct responding to recombinations of components, whereas subjects with a Concurrent history continued to respond at chance level. In Experiment 3, two subjects with a history of Concurrent training were trained using Sequential training. The subjects learned to respond to recombinations and components at criterion level. It was concluded that multiple-stimulus training, in which S+ components are presented sequentially, is an effective method for training subjects to respond to components as well as to the total multiple stimulus. Findings are discussed in relation to: (a) attention theory and implications for related areas, such as stimulus salience and functionality; (b) a reassessment of the definition of overselectivity; and (c) implications for research with other populations.

The reaction time of four groups of elderly human subjects were examined to determine the effects of stimulus presentation and task practice. Each group practiced different tasks, each requiring a response when more than one alternative was available. Two tasks involved making responses based on either visually or auditorily presented stimuli only. One task required decisions to be made on the basis of both auditory and visual stimuli. The fourth group acted as a comparison group and did not practice a reaction-time task; although they did perform a task on the computer and their reaction times were measured. Before and after practicing these tasks, each group was given a single trial involving a completely different decision-making task, and reaction time was measured. Results show that practice led to decreased reaction times on the practiced task in all treatment groups. The comparison group did not improve. Practicing any of the three reaction time tasks also led to decreased reaction time on the unpracticed task. These findings indicate that elderly individuals can decrease their reaction time with practice and that after practicing one task, changes will generalize to a different task. If the older population can alter performance on this task, then they nay also be capable of altering performance on other tasks.

The purpose of this current study was to evaluate the use of a stimulus equivalence paradigm to teach emerging adults with developmental disabilities to accurately estimate portion sizes. This study also aimed to integrate nutritionally recommended foods to incorporate a socially significant component to promote health related behaviors. Three emerging adults with various developmental disabilities participated in this study. A pre/post-test embedded in a multiple baseline design across food was used to demonstrate experimental control. Results of this study indicated that all participants exhibited accurate portion size estimations following stimulus equivalence direct training trials and test of untrained relations. When asked about their perceptions of the training methods through a social validity questionnaire participants indicated that this training method were effective and acceptable. Limitations and directions for further research are also discussed.

The purpose of the study was to evaluate the efficacy of the procedures described in the PEAK-E curriculum in teaching addition skills to children with developmental disabilities. In the present study, three participants were taught to match sample addition problems (A) to a number of pictures (B) corresponding to the sum of A (A-B), and to match sample pictures (B) to textual numbers (C) (B-C). They were then tested to see if they could match sample addition problems (A) to with the textual numbers (C) that were the solution of the addition problems A (A-C). Following mastery of the A-B and B-C relations, none of the participants were able to demonstrate the derived transitive A-C relation. An additional training phase was conducted across all participants whereby two of the five stimulus classes were provided “equivalence” C-A training (matching the textual number C to the equation A), after which all of the participants were able to demonstrate the derived transitive A-C relations across all stimulus classes without direct training of any of the stimulus classes. The results expand on previous research evaluating behavioral approaches to teaching math skills by showing how the development of equivalence class can result in the untrained emergence of novel math skills. Keywords: Stimulus Equivalence, PEAK, Addition, Autism, Developmental Disabilities

<p> Two experiments, involving 140 subjects, were performed to study the effects of two partial reinforcement variables on measures of stimulus control in extinction. Pigeons were required to make a fixed number of responses ranging from 1 to 64) to terminate discrete trial presentations and were rewarded on a predetermined percentage (ranging from 100% to 25%) of those completed trials. Generalization tests involved repeated nonreinforced presentations of the training stimulus and a new stimulus until animals ceased responding. Stimulus control measured by differences or ratios of responding to the two stimuli increased as response requirement increased. The percent of trials reinforced had no significant effect on either measure of control. Within-trial analyses showed that maximum stimulus control is exerted over the first response, some control continues to be exerted over successive responses, and there is a tendency for control to increase near the end of the requirement. Implications of the research were discussed.</p> / Thesis / Doctor of Philosophy (PhD)

<p> Three experiments, involving 250 subjects, were performed which support the conclusion that a tone cue presented shortly before a tachistoscopic stimulus facilitates tachistoscopic recognition. With tone-stimulus intervals below two seconds no threshold differences occurred. With intervals between two and eight seconds, the shorter the interval was, the lower thresholds were, and the more practice decrement observed. Experiment II showed that while the tone-stimulus interval affects thresholds the most, the interval between successive exposures of a stimulus affects thresholds. We concluded that as this interval is lengthened, the subject forgets information already gained. Experiment III showed that training in a reaction time task transferred positively to a tachistoscopic task when a two second tone-stimulus interval was used in both tasks. Reasons for the facilitative effect of the tone were discussed.</p> / Thesis / Master of Arts (MA)

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No description available.

No description available.

This thesis is concerned with intensity characteristics of conditioned stimuli in acquisition of a conditioned emotional response (CER) in rats. A comparison was made of CSs which differed (between groups) with respect to amount and direction of change in white noise from a constant background stimulation level. The measure of conditioning was the degree to which the CS disrupted ongoing, food-motivated, bar-pressing activity. The major findings were (1) that rate of conditioning was a monotonic increasing function of amount of intensity change in either direction; and (2) an increase in noise intensity from background X to CS Y produced more rapid acquisition of the CER than did a decrease from background Y to CS X. (3) During pretests, a noise increase produced a small, but reliable, Increase in rate of bar-pressing, while a noise decrease produced a slight suppression. / Thesis / Master of Arts (MA)