Two Directions in a Search for Symmetry in Rats

The Psychological Record - Two methodologies that have been successful in producing emergent symmetry in some nonhuman species include multiple exemplar training (sea lions) and successive...     

Relations between baseline contingencies and equivalence probe performances

Following the emergence of two three-member equivalence classes (A1B1C1 and A2B2C2), 5 college students were exposed to one or more changes in the reinforcement contingencies controlling baseline conditional discriminations. AC relations were either reversed (i.e., C2 was reinforced and C1 punished when A1 was the sample; C1 was reinforced and C2 punished when A2 was the sample) or arranged randomly (i.e., C2 and C1 were reinforced and punished equally often in the presence of A1 and A2). In a third condition, the original AB and AC relations were reversed. Results showed that although baseline conditional discrimination performances were under the control of reinforcement contingencies, and performances on symmetry trials varied with baseline responding for 3 of 4 subjects when contingencies were reversed, performances on transitivity probes remained consistent with the initial equivalence class. These inconsistencies between probe and baseline performances were striking because conditional discriminations are thought to be the determinants of equivalence class performance. Similarly, the contrast between performances on symmetry and transitivity probes was of theoretical interest because equivalence classes are defined by congruent patterns of responding on probe trials.     

Intervention in the Library: The Effect of Increased Responsibility on Bystanders' Willingness To Prevent a Theft

Two field experiments tested the hypothesis that a bystander's increased responsibility to act increases the likelihood of his helping the victim of an emergency. In Experiment 1, an individual asked or did not ask the bystander to protect his property in his absence. In Experiment 2, the presence/absence of an unattentive confederate was varied orthogonally to the request/no request manipulation. The results of both experiments indicated that bystanders who received a prior request for protective assistance felt more personally responsible for protecting the individual's property and were more likely to prevent a theft of that property than were bystanders who received no request. The presence of a confederate in Experiment 2 decreased bystanders' felt responsibility and their willingness to intervene on the victim's behalf. The results were interpreted as support for the "felt responsibility" proposition of the Latané and Darley (1970) model of bystander intervention.     

Adolescent Nonsmokers,Triers, and Regular Smokers' Estimates of Cigarette Smoking Prevalence: When Do Overestimations Occur and by Whom?1

The present study tested three assumptions often made by smoking prevention researchers and practitioners regarding the nature and causes of smoking prevalence estimates. Specifically, it is often assumed that (a) adolescent prevalence estimates of all levels of smoking are inflated, (b) youths at different stages of smoking onset all overestimate smoking prevalence, and (c) the predictors of these estimates are the same for youths at different stages of smoking onset. Measures of smoking behavior based on self-reports using a bogus pipeline procedure, estimates of cigarette smoking prevalence (trying behavior and weekly use), and reports of smoking in significant others were obtained by the same youths when they were in eighth and ninth grades. Results indicated that, taken over all youths, estimates of trying cigarettes were accurate, whereas estimates of weekly use were inflated. When responders were defined by their stage of smoking onset, either as a nonsmoker, trier, or regular smoker, analyses revealed that triers were accurate regarding prevalence estimates of trying, whereas non-smokers made gross underestimations and regular smokers made overestimations of trying. All groups of youths overestimated prevalence of weekly smoking. Analyses of variance revealed that both youths' smoking status and interpersonal smoking environment additively predicted prevalence estimates, and estimates of smoking prevalence were relatively higher in youths who began to smoke, or increased their levels of smoking, within the next year. Thus, previous assumptions were partially confirmed. Future research and prevention programming should focus more on regular smoking as the focus of normative smoking distortion effects and correction efforts.