Equivalence relations in individuals with language limitations and mental retardation

The study of equivalence relations exhibited by individuals with mental retardation and language limitations holds the promise of providing information of both theoretical and practical significance. We reviewed the equivalence literature with this population, defined in terms of subjects having moderate, severe, or profound mental retardation. The literature includes 55 such individuals, most of whom showed positive outcomes on equivalence tests. The results to date suggest that naming skills are not necessary for positive equivalence test outcomes. Thus far, however, relatively few subjects with minimal language have been studied. Moreover, we suggest that the scientific contributions of studies in this area would be enhanced with better documentation of language skills and other subject characteristics. With recent advances in laboratory procedures for establishing the baseline performances necessary for equivalence tests, this research area is poised for rapid growth.     

Responding for sucrose and wheel-running reinforcement: effects of sucrose concentration and wheel-running reinforcer duration

Six male albino rats were placed in running wheels and exposed to a fixed-interval 30-s schedule of lever pressing that produced either a drop of sucrose solution or the opportunity to run for a fixed duration as reinforcers. Each reinforcer type was signaled by a different stimulus. In Experiment 1, the duration of running was held constant at 15 s while the concentration of sucrose solution was varied across values of 0, 2.5. 5, 10, and 15%. As concentration decreased, postreinforcement pause duration increased and local rates decreased in the presence of the stimulus signaling sucrose. Consequently, the difference between responding in the presence of stimuli signaling wheel-running and sucrose reinforcers diminished, and at 2.5%, response functions for the two reinforcers were similar. In Experiment 2, the concentration of sucrose solution was held constant at 15% while the duration of the opportunity to run was first varied across values of 15, 45, and 90 s then subsequently across values of 5, 10, and 15 s. As run duration increased, postreinforcement pause duration in the presence of the wheel-running stimulus increased and local rates increased then decreased. In summary, inhibitory aftereffects of previous reinforcers occurred when both sucrose concentration and run duration varied; changes in responding were attributable to changes in the excitatory value of the stimuli signaling the two reinforcers.     

Evaluation of antecedent stimulus parameters for the treatment of escape-maintained aberrant behavior

We evaluated a methodology for identifying the range of stimulus features of antecedent stimuli associated with aberrant behavior in demand contexts in natural settings. For each participant, an experimental analysis of antecedents (Phase 1) was conducted to confirm the hypothesis that task instructions occasioned increases in aberrant behavior. During Phase 2, specific stimulus features associated with the presentation of task instructions were assessed by evaluating the child's behavior across two distinct settings, therapists, and types of tasks in a sequential fashion. Aberrant behavior occurred immediately across settings and therapists, presumably because the presence of a discriminative stimulus for escape-maintained behavior (the delivery of a task instruction) occasioned aberrant behavior. However, aberrant behavior decreased initially across tasks, suggesting that familiarity with the task might be a variable. During Phase 3, an experimental (functional) analysis of consequences was conducted with 2 participants to verify that aberrant behavior was maintained by negative reinforcement. During Phase 4, a treatment package that interspersed play with task instructions was conducted to disrupt the ongoing occurrence of aberrant behavior. Immediate and durable treatment effects occurred for 2 of the 3 participants.     

提取抑制:来自听觉定向遗忘的证据

两个实验采用语音材料考察了词表表达方式下听觉通道的定向遗忘效应以及相应的机制。实验一中,采用2（组别）×2（词表）混合实验设计获得了听觉通道的定向遗忘效应,但是较为模糊,部分数据显示可能是额外的被试个体差异导致的;实验二中,采用2（性别）×2（词表）×2（条件）×2（科系）混合实验设计,严格控制了被试个体差异等因素,获得了较清晰的定向遗忘效应,且支持提取抑制理论。     

Promoting the emergence of advanced knowledge: A review of peak relational training system: Direct training module by Mark R. Dixon

Mark Dixon's (2014) manual, PEAK Relational Training System: Direct Training Module, proposes a novel approach to manualized evaluation and curriculum development. Dixon's PEAK system, introduced in the book as the first of four modules, translates derived relational responding methodology into a new verbal‐behavior approach. The PEAK system is firmly rooted in the basic, conceptual, and applied behavior‐analytic tradition; however, it differs substantially from the competition in its unique application of relational frame theory to produce efficient learning. The manual's accessible nature renders it a viable product for many users and readers. The growing empirical support for PEAK’s efficacy, usability, and psychometrics is impressive and provides a robust empirical basis for the system that is not described within the pages of the manual. Behavior analysts may shy away from a manualized system that explicitly omits discussion of scholarship and empirical bases but would be remiss in doing so, given the potential of PEAK to revolutionize the way clinicians and parents apply the verbal behavior approach.     

Modality,Quantification, and Many Vlach-Operators

Consider two standard quantified modal languages \(\textbf{\textsf{A}}\) and \(\textbf{\textsf{P}}\) whose vocabularies comprise the identity predicate and the existence predicate, each endowed with a standard S5 Kripke semantics where the models have a distinguished actual world, which differ only in that the quantifiers of \(\textbf{\textsf{A}}\) are actualist while those of \(\textbf{\textsf{P}}\) are possibilist. Is it possible to enrich these languages in the same manner, in a non-trivial way, so that the two resulting languages are equally expressive—i.e., so that for each sentence of one language there is a sentence of the other language such that given any model, the former sentence is true at the actual world of the model iff the latter is? Forbes (1989) shows that this can be done by adding to both languages a pair of sentential operators called Vlach-operators, and imposing a syntactic restriction on their occurrences in formulas. As Forbes himself recognizes, this restriction is somewhat artificial. The first result I establish in this paper is that one gets sameness of expressivity by introducing infinitely many distinct pairs of indexed Vlach-operators. I then study the effect of adding to our enriched modal languages a rigid actuality operator. Finally, I discuss another means of enriching both languages which makes them expressively equivalent, one that exploits devices introduced in Peacocke (1978). Forbes himself mentions that option but does not prove that the resulting languages are equally expressive. I do, and I also compare the Peacockian and the Vlachian methods. In due course, I introduce an alternative notion of expressivity and I compare the Peacockian and the Vlachian languages in terms of that other notion.     

On the discriminability of stimulus duration.

The performance of pigeons trained to detect differences in the duration of stimuli was analysed using a matching model of signal detection. Two white stimuli, S1 and S2, differing in duration, were arranged with equal probability on the center key of a three-key chamber. S1 was systematically varied from 5 seconds to 25 seconds while S2 remained constant at 30 seconds. On completion of the center-key stimulus, a peck on the center key turned on the two red side keys. A left-key response was "correct" when S1 had been in effect on the center key and a right-key response was "correct" on S2 trials. A correct response produced a 3-second magazine light accompanied intermittently by food. Incorrect responses produced 3-second blackouts. Detection performance was measured under two procedures. In the first, the obtained reinforcement ratio was uncontrolled by allowing the number of food reinforcements obtained for correct left- and right-key responses to vary as the stimuli were changed. In the second procedure, the presentation of food reinforcement was controlled by holding the obtained reinforcement ratio constant. Discriminability changed as a function of stimulus differences under both procedures. No such trend was found in response bias.     

Stimulus control in the use of landmarks by pigeons in a touch-screen task

Pigeons were tested in a search task on the surface of a monitor on which their responses were registered by a touch-sensitive device. A graphic landmark array was presented consisting of a square outline (the frame) and a colored “landmark.” The unmarked goal, pecks at which produced reward, was located near the center of one edge of the frame, and the landmark was near it. The entire array was displaced without rotation on the monitor from trial to trial. On occasional no-reward tests, the following manipulations were made to the landmark array: (a) either the frame or the landmark was removed; (2) either one edge of the frame or the landmark was shifted; and (3) two landmarks were presented with or without the frame present. On these two-landmark tests, the frame, when present, defined which was the “correct” landmark. When the frame was absent, the “correct” landmark was arbitrarily determined. Results showed that pecks of 2 pigeons were controlled almost solely by the landmark, pecks of 3 were controlled primarily by the landmark but the frame could distinguish the correct landmark, and 1 bird's behavior was controlled primarily by the frame. Stimulus control in this search task is thus selective and differs across individuals. Comparisons to other search tasks and to other stimulus control experiments are made.     

A comparison of multiple versus single examples of the correct stimulus on task acquisition and generalization by persons with developmental disabilities

In teaching discriminations to persons with retardation, we often presume we will improve acquisition and generalization if we use multiple examples of boththe correct and incorrect stimuli. Two experiments were conducted to test this hypothesis. In the first experiment, 7 persons with moderate retardation learned to discriminate between functional words under two conditions. In one condition, Multiple Example of S- Only,1 example of the correct stimulus (S+) and 10 examples of the incorrect stimulus (S-) were used during acquisition. In the other condition, Multiple Examples of S+ and S-,10 examples of the S+ and 10 examples of the S- were used. Results showed that the condition which presented only a single example of S+ was superior 16 times and inferior 4 times during acquisition, generalization, and maintenance. A second experiment was conducted to (a) replicate the methodology and procedures in Experiment 1 with different participants, (b) determine whether the results were replicable, and (c) obtain efficiency data. Results replicated the findings of the first experiment. The condition which presented only a single example of S+ was superior on measures of (a) trials to criterion, (b) percent correct during acquisition, and (c) minutes to criterion. On measures of generalization, the two conditions were relatively equal. Thus, the condition which presented only a single example of the correct stimulus was more efficient and was just as effective in generalization as the condition which presented multiple examples of both the S+ and S-. These surprising results were discussed in terms of stimulus control, why students performed just as well during generalization when only one example of the S+ was used, why acquisition was also poorer for this condition, and how future studies might address these points.     

Discrimination of methadone and cocaine by pigeons without explicit discrimination training.

Pigeons were trained to peck a key on a variable-interval 2-min schedule of food reinforcement. Prior to each session, either 2.0 mg/kg methadone (n = 3), 3.0 mg/kg cocaine (n = 4), or 5.6 mg/kg cocaine (n = 2) was administered. When each pigeon's rate of pecking was stable, a range of doses of the training drug and saline were administered prior to 20-min extinction sessions separated by at least four training sessions. Rate of pecking during these extinction tests was generally an increasing function of dose, with the lowest rates obtained following saline and low doses and the highest rates obtained following doses near the training doses. Dose functions from pigeons trained with 5.6 mg/kg cocaine were steeper than those from pigeons trained with 3.0 mg/kg cocaine. Pigeons trained with methadone or 3.0 mg/kg cocaine were then given discrimination training, in which food reinforcement followed drug administration and 20-min extinction sessions followed saline administration. Rates of pecking under these conditions quickly diverged until near-zero rates were obtained following saline and high rates were obtained following drug. Discrimination training steepened dose functions for the training drugs, and the effects of several other substituted drugs depended on the pharmacology of the training drug. The pigeons trained with 5.6 mg/kg cocaine were tested with d-amphetamine, methadone, and morphine prior to discrimination training. d-Amphetamine increased rates dose dependently, and methadone and morphine did not. The results suggest that discriminative control by methadone and cocaine was established without explicit discrimination training.