Distractor effect on the latent inhibition of conditioned flavor aversion in rats

Using a conditioned flavor aversion procedure with rats as subjects, the effect of the addition of a distractor stimulus on the magnitude of the latent inhibition effect was examined. Experiment 1 showed that latent inhibition to vinegar was attenuated by the addition of sucrose during preexposure. On the other hand, sucrose added during conditioning to vinegar did not attenuate latent inhibition. It was also found that the degree of latent inhibition to the vinegar-sucrose compound solution was less when vinegar alone was preexposed (i.e., when sucrose was added only during conditioning) than when the compound solution was preexposed (i.e., when sucrose was added both during preexposure and during conditioning). Experiment 2 gave similar results but with sucrose assigned as the target flavor and vinegar as the distractor. These findings are in full agreement with the generalization decrement account of latent inhibition.     

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.     

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.     

THE INFLUENCE OF MOTIVATING OPERATIONS ON GENERALIZATION PROBES OF SPECIFIC MANDS BY CHILDREN WITH AUTISM

We investigated the influence of motivating operations on the generalization of newly taught mands across settings and communication partners for 3 children with autism. Two conditions were implemented prior to generalization probes. In the first condition, participants were given access to a preferred item until they rejected the item (i.e., abolishing operation). In the second condition, the item was not available to participants prior to generalization probes (i.e., establishing operation). The effects of these conditions on the generalization of newly taught mands were evaluated in a multielement design. Results indicated differentiated responding during generalization probes in which more manding with the target mand was observed following the presession no‐access condition than in the presession access condition. These results support the consideration of motivating operations when assessing generalization of target mands to various untrained contexts.     

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.     

Relational learning in a context of transposition: a review

In a typical transposition task, an animal is presented with a single pair of stimuli (for example, S3+ S4−, where plus and minus denote reward and nonreward and digits denote stimulus location on a sensory dimension such as size). Subsequently, an animal is presented with a testing pair that contains a previously reinforced or nonreinforced stimulus and a novel stimulus (for example, S2–S3 and S4–S5). Does the choice of a novel S2 instead of previously reinforced S3 in a testing pair S2–S3 indicate that the animal has learned a relation (i.e., “select smaller”)? This review of empirical evidence and theoretical accounts shows that an organism''s behavior in a transposition task is undoubtedly influenced by prior reinforcement history of the training stimuli (Spence, 1937). However, it is also affected by two other factors that are relational in nature—a similarity of two testing stimuli to each other and an overall similarity of the testing pair as a whole to the training pair as a whole. The influence of the two latter factors is especially evident in studies that use multiple pairs of training stimuli and a wide range of testing pairs comprising nonadjacent stimuli (Lazareva, Miner, Young, & Wasserman, 2008; Lazareva, Wasserman, & Young, 2005). In sum, the evidence suggests that both prior reinforcement history and relational information affect an animal''s behavior in a typical transposition task.     

The interaction of temporal generalization gradients predicts the context effect

In a temporal double bisection task, animals learn two discriminations. In the presence of Red and Green keys, responses to Red are reinforced after 1-s samples and responses to Green are reinforced after 4-s samples; in the presence of Blue and Yellow keys, responses to Blue are reinforced after 4-s samples and responses to Yellow are reinforced after 16-s samples. Subsequently, given a choice between Green and Blue, the probability of choosing Green increases with the sample duration-the context effect. In the present study we asked whether this effect could be predicted from the stimulus generalization gradients induced by the two basic discriminations. Six pigeons learned to peck Green following 4-s samples (S(+)) but not following 1-s samples (S(-)) and to peck Red following 4-s samples (S(+)) but not following 16-s samples (S(-)). Temporal generalization gradients for Green and Red were then obtained. Finally, the pigeons were given a choice between Green and Red following sample durations ranging from 1 to 16 s. Results showed that a) the two generalization gradients had the minimum at the S(-) duration, an intermediate value between the S(-) and the S(+) durations, and the maximum at the S(+) as well as more extreme durations; b) on choice trials, preference for Green over Red increased with sample duration, the context effect; and c) the two generalization gradients predicted the average context effect well. The Learning-to-Time model accounts for the major trends in the data.     

Rethinking reinforcement: allocation, induction, and contingency

The concept of reinforcement is at least incomplete and almost certainly incorrect. An alternative way of organizing our understanding of behavior may be built around three concepts: allocation, induction, and correlation. Allocation is the measure of behavior and captures the centrality of choice: All behavior entails choice and consists of choice. Allocation changes as a result of induction and correlation. The term induction covers phenomena such as adjunctive, interim, and terminal behavior-behavior induced in a situation by occurrence of food or another Phylogenetically Important Event (PIE) in that situation. Induction resembles stimulus control in that no one-to-one relation exists between induced behavior and the inducing event. If one allowed that some stimulus control were the result of phylogeny, then induction and stimulus control would be identical, and a PIE would resemble a discriminative stimulus. Much evidence supports the idea that a PIE induces all PIE-related activities. Research also supports the idea that stimuli correlated with PIEs become PIE-related conditional inducers. Contingencies create correlations between "operant" activity (e.g., lever pressing) and PIEs (e.g., food). Once an activity has become PIE-related, the PIE induces it along with other PIE-related activities. Contingencies also constrain possible performances. These constraints specify feedback functions, which explain phenomena such as the higher response rates on ratio schedules in comparison with interval schedules. Allocations that include a lot of operant activity are "selected" only in the sense that they generate more frequent occurrence of the PIE within the constraints of the situation; contingency and induction do the "selecting."     

Hume and the nominalist tradition

Many of the central theses of Hume's philosophy – his rejection of real relations, universals, abstract objects and necessary causal relations – had precedents in the later medieval nominalist tradition. Hume and his medieval predecessors developed complex semantic theories to show both how ontologies are apt to become inflated and how, if we understand carefully the processes by which meaning is generated, we can achieve greater ontological parsimony. Tracing a trajectory from those medieval traditions to Hume reveals Hume to be more radical, particularly in his rejection of abstraction and abstract ideas. Hume's denial of general, abstract ideas is consistent with his philosophical principles but fails to appreciate the more sophisticated nominalist approaches to abstraction, the result of which is a theoretically impoverished account of our capacity for generalization.     

Some determinants of remote behavioral history effects in humans

Undergraduates were exposed to a series of reinforcement schedules: first, to a fixed-ratio (FR) schedule in the presence of one stimulus and to a differential-reinforcement-of-low-rate (DRL) schedule in the presence of another (multiple FR DRL training), then to a fixed-interval (FI) schedule in the presence of a third stimulus (FI baseline), next to the FI schedule under the stimuli previously correlated with the FR and DRL schedules (multiple FI FI testing), and, finally, to a single session of the multiple FR DRL schedule again (multiple FR DRL testing). Response rates during the multiple FI FI schedule were higher under the former FR stimulus than under the former DRL stimulus. This effect of remote histories was prolonged when either the number of FI-baseline sessions was small or zero, or the time interval between the multiple FR DRL training and the multiple FI FI testing was short. Response rates under these two stimuli converged with continued exposure to the multiple FI FI schedule in most cases, but quickly differentiated when the schedule returned to the multiple FR DRL.