A COMPARISON OF NONCONTINGENT REINFORCEMENT AND SENSORY EXTINCTION AS TREATMENTS FOR SELF-INJURIOUS BEHAVIOR

We compared the effects of two treatments, noncontingent reinforcement (NCR) and sensory extinction (EXT), on the self-injurious behavior (SIB) exhibited by 3 individuals with developmental disabilities. Results of a functional analysis indicated that their SIB was not maintained by social reinforcement, as indicated by undifferentiated responding across assessment conditions or higher rates of responding in the alone condition. Prior to treatment, leisure probes were conducted to identify highly preferred items for use in the NCR condition, and equipment probes were conducted to identify devices that produced the greatest behavioral suppression for use in the EXT condition. Following baseline, treatment was implemented in a multiple baseline across subjects design, and the effects of NCR and EXT were compared in a multielement format. During NCR sessions, participants had continuous access to a highly preferred item. During EXT sessions, participants wore equipment (gloves or protective sleeves) that seemed to attenuate stimulation directly produced by their SIB, while still allowing the behavior to occur. Results indicated that both procedures were effective in reducing SIB, although NCR was associated with either more rapid or greater overall response suppression.     

EQUATING INVERSE PROBABILITIES IN IMPLICIT PERSONALITY JUDGMENTS

Abstract— Meehl and Rosen (1955) observed that their colleagues tended to equate the sensitivity of a sign (its probability given a diagnostic category) with its predictive accuracy (the probability of the diagnostic category given the sign). Such equating of inverse probabilities implies ignoring base rates. Later, many researchers demonstrated such neglect in a number of experimental contexts involving hypothetical judgments; others have found some use of base rates—but only when base rates were supplied by the experimenter, in which case even irrelevant base rates influenced judgment. The present study tested for equating conditional probabilities in a context similar to the contexts involved in the initial observations—that is, subjects strove for accuracy rather than attempted to make good judgments about hypothetical problems, and the base rates were generated by the subjects themselves. Neglect of base rates was revealed by within-individual comparisons showing subjects equated inverse probabilities without equating the corresponding unconditional ones.     

The backpropagation algorithm: Implications for the biological bases of individual differences in intelligence

Variations in brain structure and function may explain individual variation in human intelligence. However, it is not currently possible to directly examine this hypothesis. As an indirect examination, a neural network employing the backpropagation algorithm to solve the exclusive-or function was manipulated to possess different numbers of processing elements (neurons), connections (synapses), and conduction failure (synaptic failure). The effect of the variations on network accuracy and energy utilization were compared to human reaction time and cerebral metabolic data to evaluate which variations most reliably reproduced the human results. Varying the synaptic failure rate appears essential for mimicking the human reaction time data and increasing network connectivity is the most efficient way to improve network accuracy for a given degree of neuronal activation. The results suggest that variations in the physiologic events of synaptic neurotransmission and variations in the structural interconnectivity of the neurons in the brain will be found to underline an important portion of the variation in human intelligence.