MATCHING-TO-SAMPLE PERFORMANCE IN RATS: A CASE OF MISTAKEN IDENTITY?

Three rats had previously acquired a simultaneous matching-to-sample performance with steady and blinking lights. In training, the sample stimulus had always appeared on the middle of three horizontally arranged keys with the comparison stimuli on the side keys. In Experiment 1, the sample stimulus appeared on any of the three keys with the comparison stimuli on the remaining two. The matching-to-sample performance broke down with variable sample and comparison locations; the sample stimulus did not control responding to the comparison stimuli when it appeared on a side key, but it retained control when it appeared on the middle key (as in training). In Experiment 2, the rats were trained with the sample always on the left key. When the sample appeared on either of the trained locations (left or middle key), it retained control for both locations. When the sample then appeared on any of the three keys, as in Experiment 1, sample control did not transfer to the untrained location (right key). The experiments demonstrate that training with fixed sample and comparison locations may establish spatial location as an additional controlling aspect of the stimuli displayed on the keys; stimulus location had become part of the definition of the controlling stimuli. The rats' performance seemed best described as specific discriminations involving the visual stimuli and their spatial locations rather than as identity matching.     

Left or right? Sources of political orientation: the roles of genetic factors, cultural transmission, assortative mating, and personality

In this study, we used an extended twin family design to investigate the influences of genetic and cultural transmission as well as different sources of nonrandom mating on 2 core aspects of political orientation: acceptance of inequality and rejecting system change. In addition, we studied the sources of phenotypic links between Big Five personality traits and political beliefs using self- and other reports. Data of 1,992 individuals (224 monozygotic and 166 dizygotic twin pairs, 92 unmatched twins, 530 spouses of twins, 268 fathers, and 322 mothers) were analyzed. Genetically informative analyses showed that political attitudes are genetically but not environmentally transmitted from parents to offspring and that a substantial proportion of this genetic variance can be accounted for by genetic variance in personality traits. Beyond genetic effects and genotypic assortative mating, generation-specific environmental sources act to increase twins' and spouses' resemblance in political beliefs. The results suggest multiple sources of political orientations in a modern democracy.     

The association between implicit theories of personality and the attributional process

The influence of implicit theories of personality (entity vs. incremental theorists; see Dweck, Chiu and Hong, 1995) on the stages of the Sequential Operations Model of attribution (Gilbert, Pelham, and Krull, 1988) was investigated. Two hundred eighty Norwegian participants were given a Norwegian translation of the implicit personality theories measure. Participants then read two essays, one advocating the pro-life position and the other advocating the pro-choice position on the abortion issue. The essay positions were ostensibly assigned rather than freely chosen by the author. After each essay, participants were asked to rate the essay position and the true attitude of the author. Entity and incremental theorists showed no differences in their ratings of the essay position; however, entity theorists made significantly stronger correspondent inferences about the author's attitude than did incremental theorists. These results support the contention that entity theorists engage in less attributional correction than incremental theorists.