William V. Dube

Stimulus control topography coherence theory: Foundations and extensions

Stimulus control topography refers to qualitative differences among members of a functional stimulus class. Stimulus control topography coherence refers to the degree of concordance between the stimulus properties specified as relevant by the individual arranging a reinforcement contingency (behavior analyst, experimenter, teacher, etc.) and the stimulus properties that come to control the behavior of the organism (experimental subject, student, etc.) that experiences those contingencies. This paper summarizes the rationale for analyses of discrimination learning outcomes in terms of stimulus control topography coherence and briefly reviews some of the foundational studies that led to this perspective. We also suggest directions for future research, including pursuit of conceptual and methodological challenges to a complete stimulus control topography coherence analysis of processes involved in discriminated and generalized operants.

Toward a behavioral analysis of joint attention.

Joint attention (JA) initiation is defined in cognitive-developmental psychology as a child’s actions that verify or produce simultaneous attending by that child and an adult to some object or event in the environment so that both may experience the object or event together. This paper presents a contingency analysis of gaze shift in JA initiation. The analysis describes reinforcer-establishing and evocative effects of antecedent objects or events, discriminative and conditioned reinforcing functions of stimuli generated by adult behavior, and socially mediated reinforcers that may maintain JA behavior. A functional analysis of JA may describe multiple operant classes. The paper concludes with a discussion of JA deficits in children with autism spectrum disorders and suggestions for research and treatment.

The Search for Stimulus Equivalence in Nonverbal Organisms

A currently unresolved issue in stimulus equivalence research is the relation of equivalence and language competence. The current consensus is that equivalence according to widely adopted criteria proposed by Sidman has not yet been demonstrated in nonverbal experimental subjects. This judgment rests primarily on the failure of nonhuman subjects to display the equivalence outcome under conditions comparable to those used with human subjects. We discuss theoretical and methodological issues that arise in research seeking to delineate the “lower limits” of equivalence phenomena in studies with laboratory animals or nonverbal humans. We propose a behavior-analytic approach to the question, examine the relationship between functional stimulus classes and equivalence classes, and describe some preliminary studies.

Prenatal ethanol exposure, generalized learning impairment, and medial prefrontal cortical deficits in rats.

Prenatal ethanol exposure may cause neurological damage and subsequent mental retardation in humans, with learning deficits similar to those following damage to the prefrontal cortex. This study examined cognitive dysfunction and cortical damage after prenatal exposure to ethanol using a chronic administration model. Pregnant Sprague-Dawley rats received one of three diets during gestation: a liquid diet containing 35% ethanol-derived calories (ETOH), an isocaloric liquid diet (ISO), or standard chow (CHOW). Subjects were obtained from ETOH dams with blood alcohol concentrations (BACs) above 90 mg/dl and corresponding ISO and CHOW controls (one male pup/litter; n=6 pups/group). At approximately 90 days of age, subjects began training on a series of unique auditory discrimination problems using a successive go/no-go procedure. A criterion of 85% accuracy determined when a rat continued to the next problem. Subjects completed a varying number of problems within a 30-session limit, after which all rats were tested on a tone/click discrimination and reversal. Subjects were then sacrificed and neuronal number in the medial prefrontal cortex (mPFC) was estimated by the optical fractionator method. Prenatal ethanol exposure induced significant cell loss in the mPFC, which was associated with significantly impaired reversal learning. Poor performance by ETOH subjects on the tone/click reversal indicates a transfer of training deficit that may reflect failures of inhibitory control.

Stimulus class formation and functional equivalence in moderately retarded individuals' conditional discrimination

Three mentally retarded humans first acquired a simple discrimination: Simultaneously displayed visual stimuli A1 and A2 functioned as S+ and S-, respectively. The subjects also acquired a conditional discrimination, learning to select visual stimuli B1 and B2 conditionally upon A1 and A2, respectively. Then, B1 and B2 were displayed without A1 or A2. Subjects selected B1, an emergent discrimination that showed that B1 and B2 had become functionally equivalent to A1 and A2, respectively. Two subjects next learned to select C1 and C2 conditionally upon B1 and B2, respectively. They also learned to select B1 and B2 conditionally upon D1 and D2, respectively. Subsequent simple discrimination probe trials displayed (a) C1 and C2 and (b) D1 and D2. On the former, the subjects nearly always selected C1. On the latter, they initially selected D1 and D2 about equally often. Thus, the emergence of simple discrimination appears to depend on a specific experimental history.

An analysis of generalized identity matching-to-sample test procedures

This paper examines issues that must be considered when evaluating generalized identity matching to sample. We suggest that (a) stimuli displayed together on tests of generalized identity matching should have comparable experimental histories, and (b) identity matching procedures should be differentiated as either “conditional” or “nonconditional,” depending upon whether or not conditional discrimination is required. Although either type of procedure might be adequate for demonstrating a “matching concept,” we suggest that only generalized conditional identity matching provides an adequate test for the reflexive property of conditional relations.

11 Some implications of a stimulus control topography analysis for emergent behavior and stimulus classes

Publisher Summary The chapter discusses some implications of stimulus control topography (SCT) analysis for emergent behavior and stimulus classes. Equivalence outcomes result when (1) baseline training establishes the experimentally relevant SCT, and (2) this SCT occurs with a high frequency. The pattern of data that would support this analysis is a relation between the degree of experimental control over the definition and frequency of the baseline SCT and the rate and proportion of positive equivalence outcomes. This relation leads to two predictions: (1) the occurrence of delayed emergence and equivalence failures should be reduced by instituting procedures that increase the coherence between the subjects and experimenters SCT definition, and (2) when baseline contingencies permit multiple SCTs and delayed emergence and equivalence failures do occur, then procedures that eliminate the irrelevant SCTs in the baseline or from the test trials should produce immediate increases in equivalence outcomes.

Assessing same/different judgments in individuals with severe intellectual disabilities: A status report☆

This report summarizes state-of-the-art approaches for assessing visual stimulus same/different judgments in individuals with severe intellectual disabilities. Methods are described that permit one to conduct assessments on a population-wide basis, excluding few if any participants due to failure to acquire necessary baseline performances. Methodological investigations summarized here indicate that one can obtain reliable same/different judgments with a variety of stimuli in virtually anyone for whom a basal score on the Peabody Picture Vocabulary Test can be obtained. This approach includes judgments involving not only familiar, readily nameable stimuli, but also abstract two-dimensional forms of the type commonly used to minimize extraexperimental influences on performance. Taken together, recent findings lead to the conclusion that past studies have significantly under-estimated the capacity of participants with low MA scores to make same/different judgments. They also suggest a more general methodological approach that can potentially lead to more sensitive assessment of other behavioral capacities in this difficult-to-test population.

RESISTANCE TO DISRUPTION IN A CLASSROOM SETTING

Substantial experimental evidence indicates that behavior reinforced on a denser schedule is more resistant to disruption than is behavior reinforced on a thinner schedule. The present experiment studied resistance to disruption in a natural educational environment. Responding during familiar activities was reinforced on a multiple variable-interval (VI) 7-s VI 30-s schedule for 6 participants with developmental disabilities. Resistance to disruption was measured by presenting a distracting item. Response rates in the disruption components were compared to within-session response rates in prior baseline components. Results were consistent with the predictions of behavioral momentum theory for 5 of 6 participants.

Fast Mapping and Exclusion (Emergent Matching) in Developmental Language, Behavior Analysis, and Animal Cognition Research

Researchers from behavior analytic, developmental, and comparative perspectives have all investigated the conditions under which new arbitrary (symbolic) stimulus-stimulus relations are acquired. For example, young children, people with severe mental retardation, and several species of nonhuman mammals all exhibit emergent matching (EM) in the context of a wellestablished matching-to-sample baseline: When presented with an undefined sample stimulus and a comparison array that includes one undefined comparison and one or more baseline comparisons, participants select the undefined comparison. Further, subsequent testing may show a learning outcome: Exposure to EM trials may result in a new defined relation involving the formerly undefined stimuli. Between 1974 and the late 1980s, emergent matching and learning outcomes were described independently by behavior analytic, child language, and animal cognition researchers. Cross-literature citations were virtually absent, however. More recently, crossdisciplinary citations have begun to appear. This article briefly reviews the history of EM research, emphasizing the independent development of research programs, methods, and terminology in the three disciplines. We then identify several research areas where a multidisciplinary approach may benefit all concerned.