The substitutability of reinforcers

Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included.     

Literalism as a marker of hypnotic "trance": disconfirming evidence

The responses given by highly hypnotizable, hypnotic subjects and those of unhypnotizable subjects who simulated hypnosis to questions of the type, "Do you mind telling me your name?" and "Do you mind standing up?" were contrasted. The purpose was to examine Erickson's (1980) assertion that literalism (answering "yes" or "no" verbally or nonverbally without any cognitive elaboration) is a marker of hypnotic "trance." Simulators exhibited a greater rate of literalism than hypnotic "virtuosos" (i.e., extreme scorers on both group and individual hypnotizability measures). Hypnotized subjects and nonhypnotized subjects approached in the campus library responded comparably. Because less than a third of hypnotic virtuosos responded literally, our results strongly refuted Erickson's assertion that literalism is a cognitive feature of hypnosis.     

Hemispheric involvement in shadowing vs. interpretation: a time-sharing study of simultaneous interpreters with matched bilingual and monolingual controls

A time-sharing study used shadowing and interpretation/paraphrasing tasks to evaluate lateralization in professional interpreters individually matched to bilingual and monolingual controls. A two-step multivariate general linear model procedure was used to determine lateralized effects and extent of disruption produced by the tasks. Results revealed the monolingual group to be left lateralized for both tasks, but the two bilingual groups were lateralized in the LH only for shadowing. The monolingual group was significantly different from the bilingual groups in the pattern of hand asymmetry for interpretation/paraphrasing. The findings replicate outcomes of prior repeated measures analysis of variance procedures on percentage of change scores. However, new information is added by the more refined analysis. The findings are also discussed in terms of previous laterality studies using similar tasks and subject samples.     

Whose Gene Is It? A Case Discussion About Familial Conflict over Genetic Testing for Breast Cancer

A multidisciplinary group of genetic and other professionals discuss a complex case of familial conflict over access to genetic information. One twin wishes to know the results of her deceased mother's tests for BRCA1 mutations; a second twin objects to researchers making this information available. As the case discussion unfolds, the apparent facts of this case are called into question and the lines of ethical certainty become less clear.     

Mathematica: A flexible design environment for neural networks

Several neural networks were developed inMathematica in order to explore the role of “spiky” neurons in neural network memory simulations. UsingMathematica for this task confirmed its value as a powerful tool for neural network development: It exhibited distinct advantages over other environments in programming ease, flexibility of data structures, and the graphical assessment of network performance.     

Need probability affects retention: A direct demonstration

Recent memory theory has emphasized the concept ofneed probability—that is, the probability that a given piece of learned information will be tested at some point in the future. It has been proposed that, in real-world situations, need probability declines over time and that the memory-loss rate is calibrated to match the progressive reduction in need probability (J. R. Anderson & Schooler, 1991). The present experiments were designed to examine the influence of the slope of the need-probability curve on the slope of the retention curve. On each of several trials, subjects memorized a list of digits, then retained the digits in memory for 1, 2, 4, 8, or 16 sec. Some trials ended with a recall test; other trials ended with the message, “no test.” In Experiment 1, the likelihood of encountering a memory test (i.e., the need probability) was made to either increase or decrease as the retention interval increased; in Experiment 2, need probability either was flat (invariant across retention intervals) or decreased as the retention interval increased. The results indicated that the shape of the need-probability curve influenced the slope of the retention curve (Experiment 1) and that the effect became larger as the experimental session progressed (Experiment 2). The findings support the notion that memory adapts to need probabilities and that the rate of forgetting is influenced by the slope of the need-probability curve. In addition, all of the forgetting curves approximated a power function, suggesting that need probability influences the slope but not the form of forgetting.     

ANALYZING ALERTNESS AMONG PEOPLE WITH PROFOUND MULTIPLE DISABILITIES: IMPLICATIONS FOR PROVISION OF TRAINING

We investigated whether variations in alertness among individuals with profound multiple disabilities affected subsequent responsiveness to training programs. Three experiments were conducted involving 5 people. In Experiment 1, results indicated that alertness of 3 individuals increased with provision of skill-acquisition training programs. Results also indicated no predictive relationship between alertness levels prior to training and subsequent responsiveness to training. Experiment 2 replicated results of Experiment 1 with 2 participants from Experiment 1 and an additional participant. Results of Experiment 2 also indicated that the increased alertness levels accompanying provision of training were not a function of the participants simply being in an inactive environment prior to training. Results of Experiment 3 indicated that alertness of an additional participant increased through provision of another training intervention, involving a systematic preference assessment. Responses during the preference assessment appeared to be unrelated to previously existing alertness levels. These findings suggest the need for caution when considering the withholding of scheduled training because an individual appears to be nonalert.     

The Imaginary Audience, Self-Consciousness, and Public Individuation in Adolescence

ABSTRACT In this study, we examined the construct of the imaginary audience (Elkind & Bowen, 1979), presumably a precipitant of adolescent egocentrism, as it relates to public individuation and self-consciousness. We hypothesized that the imaginary audience inhibits public individuation and represents a critical form of public self-consciousness. We also argued that the imaginary audience is a normal aspect of early adolescent development that diminishes in the context of secure parental relationships by late adolescence but remains salient if these relationships are insecure. These hypotheses were examined in a cross-sectional study of 850 adolescents in the 7th, 8th, 9th, and 12th grades. Support was generally found for the hypothesized relations. The validity and limitations of the imaginary audience and public individuation constructs are discussed, along with more general theoretical issues concerning adolescent self-consciousness.