Applications of computer-based instruction: using specialized software to aid letter-name and letter-sound recognition

We evaluated computerized training and testing programs with children who were having difficulties learning prereading skills. The programs were derived from equivalence research and were written in authoring software designed for educators. After learning to match uppercase and lowercase printed letters to the corresponding letter names (Tasks 1 and 2), the children matched the letters to one another (Tasks 4 and 5). Then, after learning to match uppercase letters to sounds (Task 3), they also matched lowercase letters to sounds (Task 6) and matched printed to spoken words (Tasks 7 and 8). The results recommend equivalence-based protocols and user-friendly software in further development of prereading instruction.     

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.     

On Selective Left Neglect during Walking in a Child

In this article we describe a child affected by right parieto-occipital lesion due to head injury. The patient showed left hemianopia, but not unilateral spatial neglect on traditional paper-and-pencil tests and on "ecological" tests. However, his parents reported frequent collisions with obstacles on the left side. A specific test was set up: The patient had to kick down skittles put on both sides of a route traced on the floor. He kicked down 89% of skittles on the right, but only 38% on the left side. These findings are discussed in light of recent theories on unilateral neglect.     

Relations among equivalence, naming, and conflicting baseline control

Three studies were conducted with different groups of 6 students each to explore the effects of training class-inconsistent relations and naming on demonstrations of emergent arbitrary stimulus relations. In all studies, two three-member equivalence classes of Greek symbols (A1B1C1 and A2B2C2) emerged as a result of training in conditional discriminations. Two new symbols were introduced (X and Y), and additional conditional discriminations were trained, whereby X was designated as the positive discriminative stimulus (S+) and Y was designated as the negative discriminative stimulus (S-) for A1 and B2. Conversely, Y was designated as the S+ and X as the S- for B1 and A2. This introduced conflicting sources of control within and between classes. In Study 1, subjects were not provided with names for the stimuli. In Study 2, the experimenter provided common names for the stimuli within each class. In Study 3, the subjects were required to use the common names during conditional discrimination training and test-trial blocks. In all experiments, equivalence responding with respect to the original classes was disrupted for some subjects subsequent to learning the new relations. Furthermore, in Studies 2 and 3, there were frequent examples of noncorrespondence between observed (listener or speaker) naming patterns and derived relations. These results support the view that demonstrations of equivalence are subject to control from a variety of sources rather than being fundamentally dependent on naming.     

A discrimination analysis of training-structure effects on stimulus equivalence outcomes.

Experiments designed to establish stimulus equivalence classes frequently produce differential outcomes that may be attributable to training structure, defined as the order and arrangement of baseline conditional discrimination training trials. Several possible explanations for these differences have been suggested. Here we develop a hypothesis based on an analysis of the simple simultaneous and successive discriminations embedded in conditional discrimination training and testing within each of the training structures that are typically used in stimulus equivalence experiments. Our analysis shows that only the comparison-as-node (many-to-one) structure presents all the simple discriminations in training that are subsequently required for consistently positive outcomes on all tests for the properties of equivalence. The sample-as-node (one-to-many) training structure does not present all the simple discriminations required for positive outcomes on either the symmetry or combined transitivity and symmetry (equivalence) tests. The linear-series training structure presents all the simple discriminations required for consistently positive outcomes on tests for symmetry, but not for symmetry and transitivity combined (equivalence) or transitivity alone. Further, the difference in the number of simple discriminations presented in comparison-as-node training versus the other training structures is larger when the intended class size is greater than three or the number of classes is larger than two. We discuss the relevance of this analysis to interpretations of stimulus equivalence research, as well as some methodological and theoretical implications.     

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.     

远、近空间内注意加工的分离

临床证据发现空间忽视症病人对于近处和远处空间内的注意加工存在差异,表现为空间忽视只发生于近处空间或只发生于远处空间,提示近处空间与远处空间在脑内可能是分别表征的。对健康成人的研究也发现了与之类似的近处空间和远处空间注意的分离现象,即在近处空间表现出左偏的伪忽视现象,在远处空间表现出左偏减弱或者右偏的趋势。本文综述了远、近空间内注意加工分离的实验证据以及采用线段二分任务这一主要的研究范式相关的实验结果,并且着重指出了远、近空间的划分不是绝对的,而是动态可变的研究证据。最后,指出了将来的研究需要深入考察空间参照系统在远、近空间知觉中的作用,以及关注社会交互情境下的远、近空间距离认知的动态变化。     

THE EFFECTS OF THE QUESTION “WHAT IS THIS?” ON TACT-TRAINING OUTCOMES OF CHILDREN WITH AUTISM

Tact training is a common element of many habilitative programs for individuals with developmental disabilities. A commonly recommended practice is to include a supplemental question (e.g., “What is this?”) during training trials for tacts of objects. However, the supplemental question is not a defining feature of the tact relation, and prior research suggests that its inclusion might sometimes impede tact acquisition. The present study compared tact training with and without the supplemental question in terms of acquisition and maintenance. Two of 4 children with autism acquired tacts more efficiently in the object-only condition; the remaining 2 children acquired tacts more efficiently in the object + question condition. During maintenance tests in the absence of the supplemental question, all participants emitted tacts at end-of-training levels across conditions with no differential effect observed between training conditions.Key words: autism, language training, stimulus control, tacts, verbal behaviorSkinner (1957) defined the tact as a response “evoked by a particular object or event or property of an object or event” (p. 82) and considered it to be one of the most important verbal operants. Tacts are maintained by generalized social reinforcement and, thus, they are central to many social interactions. For example, the tact “That cloud looks like a horse” (under the control of a visual stimulus) could evoke a short verbal interaction about the sky or horses. The tact “My tummy hurts” (under the control of an interoceptive stimulus) could evoke soothing statements from a parent. A child who tacts “doggie” in the presence of a cat likely would evoke a correction statement from an adult, further refining two stimulus classes (i.e., dog and cat). These examples illustrate that, despite their topographical differences, the tact relations share antecedent control by a nonverbal discriminative stimulus (S^D) and are maintained by generalized social reinforcement.In habilitative programs for individuals with language impairments, autism, and intellectual disabilities, tacts often are taught for objects (e.g., ball), object features (e.g., color, size, shape), activities (e.g., jumping), prepositions (e.g., between), and emotions (e.g., sad) among others. Although conceptualized differently among therapeutic approaches, the tact relation occupies a central position in many early-intervention curricula. For example, Lovaas (2003) and Leaf and McEachin (1999) describe these relations as expressive labels and recommend that they be taught early in language training using three-dimensional objects accompanied by the supplemental questions “What is it?” or “What''s this?” Alternatively, Sundberg and Partington (1998) explicitly refer to the relation as a tact and recommend beginning instruction by including the question “What is it?” before eventually fading the question. In addition to these clinical manuals, the use of supplemental questions during tact training has appeared in some empirical studies on tact or expressive-label training (e.g., Braam & Sundberg, 1991; Coleman & Stedman, 1974), but not others (e.g., Williams & Greer, 1993). Regardless of whether tact training initially includes supplemental questions prior to response opportunities, tacts ultimately should be emitted readily under the sole control of the nonverbal S^D as well as when it happens to be accompanied by a question.Conceptually, at least four potential problems could arise from introducing supplemental questions early and consistently in tact training. First, the acquired responses might not be emitted unless the question is posed (i.e., prompt dependence). This problem would lead to few spontaneous tacts occurring outside the explicit stimulus control of the training environment. Williams and Greer (1993) compared comprehensive language training conducted under the stimulus control specified in Skinner''s (1957) taxonomy of verbal behavior to a more traditional psycholinguistic perspective with supplemental questions and instructions embedded within trials. For all three adolescents with developmental disabilities, the targets taught from the verbal behavior perspective were maintained better in natural contexts than those taught from the psycholinguistic perspective. However, because data were not reported for each individual verbal operant, it is unclear what specific impact their tact-training procedures had on the outcomes.The second potential problem is that the supplemental question might acquire intraverbal control over early responses and interfere with the acquisition of subsequent tact targets. For example, Partington, Sundberg, Newhouse, and Spengler (1994) showed that the tact repertoire of a child with autism had been hindered by prior instruction during which she was asked “What is this?” while being shown an object. The supplemental question subsequently evoked previously acquired responses and blocked the ability of new nonverbal S^Ds (i.e., objects) to evoke new responses. Partington et al. then showed that new tacts were acquired by eliminating the supplemental question from instructional trials.The third potential problem is that learners might imitate part of or the entire supplemental question prior to emitting the target response (e.g., “What is it” → “What is it … ball.”). For example, Coleman and Stedman (1974) demonstrated that a 10-year-old girl with autism imitated the question “What is this?” while being taught to label stimuli depicted in color photographs. Such an outcome results in a socially awkward tact repertoire and requires additional intervention to remedy the problem.Finally, including supplemental questions during tact training might impede skill acquisition, perhaps via a combination of the problems described earlier. Sundberg, Endicott, and Eigenheer (2000) taught sign tacts to two young children with autism who had prior difficulty acquiring tacts. In one condition, the experimenter held up an object and asked, “What is that?” In the comparison condition, the experimenter intraverbally prompted the participant to “sign [object name]” in the presence of the object. Sundberg et al. demonstrated substantially more efficient tact acquisition under the sign-prompt condition than when the question “What is that?” was included in trials; the latter condition sometimes failed to produce mastery-level responding.Teaching an entire tact repertoire while including supplemental questions (e.g., “What is it?”) during training trials could produce a learner who is able to talk about his or her environment only when asked to do so with similar questions. To the extent that this is not a therapist''s clinical goal, teaching the tact under its proper controlling variables may eliminate such problems. Of course, inclusion of supplemental questions during the early phases of language training could be faded over time such that the target tact relation is left intact prior to the end of training (Sundberg & Partington, 1998). However, the aforementioned studies have documented problems with using supplemental questions during tact training. Given the ubiquity of tact training in habilitation programs, the numerous problems that may arise when supplemental questions are included in training trials, and the limited research on the topic, further investigation is warranted. Thus, the purpose of the present study was to compare directly the rate of acquisition and subsequent maintenance of tacts taught using only a nonverbal S^D (i.e., object only) with tacts taught using a question (“What is this?”) in conjunction with the nonverbal S^D (i.e., object + question). The present study extends earlier research by examining both acquisition and maintenance and by including individuals with no prior history of formal tact training.     

An evaluation of the stimulus equivalence paradigm to teach single-subject design to distance education students via blackboard

The purpose of the current study was to examine the degree to which instruction based on stimulus equivalence procedures could be used to teach single-subject design methodology to graduate-level professionals through a Web-based course management system known as Blackboard (see http://www.blackboard.com). Specifically, we used the stimulus equivalence paradigm to teach relations among the names, definitions, graphical representations of the designs, and two practical scenarios of when it would be appropriate to implement each design. Most participants demonstrated the emergence of untaught relations, and some participants showed generalization to novel vignettes and graphs. Relations largely were not maintained at follow-up but were retaught.