A computer model of auditory stream segregation

A computer model is described which simulates some aspects of auditory stream segregation. The model emphasizes the explanatory power of simple physiological principles operating at a peripheral rather than a central level. The model consists of a multi-channel bandpass-filter bank with a “noisy” output and an attentional mechanism that responds selectively to the channel with the greatest activity. A “leaky integration” principle allows channel excitation to accumulate and dissipate over time. The model produces similar results to two experimental demonstrations of streaming phenomena, which are presented in detail. These results are discussed in terms of the “emergent properties” of a system governed by simple physiological principles. As such the model is contrasted with higher-level Gestalt explanations of the same phenomena while accepting that they may constitute complementary kinds of explanation.     

Understanding choice utterances

When individuals offer choices, they intend them to be mandatory (requiring action) or permissive (not requiring action), and they intend them to be open (allowing the choice of both options) or closed (not allowing the choice of both options). In two studies subjects were presented with sets of syntactically equivalent disjunctive sentences with varying content designed to represent four patterns of permitted choice. The research indicates that individuals distinguish four distinct uses of “or” in deontic contexts, and that individuals more often judge choices as mandatory than permissive. The research also compared responses to questions about choice giver intent and receiver choice. The data indicate that when judging intent, individuals are inclined to understand some choices to be permissive. However, when judging what action they might take as choice receiver, subjects tend to regard action to be mandatory. It appears that although people have some facility in assessing a permission giver's intent, they often apply a more restrictive rule to themselves than is required by the choice giver.     

Effects of dopamine transporter and receptor polymorphisms on smoking cessation in a bupropion clinical trial.

This study examined the role of dopaminergic genes in prospective smoking cessation and response to bupropion treatment in a placebo-controlled clinical trial. Smokers of European ancestry (N=418) provided blood samples for genetic analysis and received either bupropion or placebo (10 weeks) plus counseling. Assessments included the dopamine D2 receptor (DRD2) genotype, dopamine transporter (SLC6A3) genotype, demographic factors, and nicotine dependence. Smoking status was verified at the end of treatment (EOT) and at 6-month follow-up. The results provided evidence for a significant DRD2 * SLC6A3 interaction effect on prolonged smoking abstinence and time to relapse at EOT, independent of treatment condition. Such effects were no longer significant at 6-month follow-up, however. These results provide the first evidence from a prospective clinical trial that genes that alter dopamine function may influence smoking cessation and relapse during the treatment phase.