Learned helplessness in the cockroach (Periplaneta americana)

For 3 consecutive days cockroaches (Periplaneta americana) were exposed to either escapable, inescapable, or no shock in an escape task. Twenty-four hours later they were tested in a shuttlebox escape task. There were reliable differences between escapable and inescapable animals and between inescapable and control animals in both escape latencies and the number of failures to escape.     

Cerebral hemispheric mechanisms in the retrieval of ambiguous word meanings

Targets related to ambiguous primes were projected to the left and right visual fields in a lexical priming experiment with stimulus onset asynchronies (SOA) of 35 and 750 msec. Right visual field results were similar to our earlier results with central projection (G. B. Simpson & C. Burgess, 1985, Journal of Experimental Psychology: Human Perception and Performance, 11, 28-39). Facilitation was found for the more frequent meaning at both SOAs and a decrease in facilitation for the less frequent meaning at the longer SOA. In contrast, left visual field results indicated a decay of facilitation for the more frequent meaning at the longer SOA, while activation for the subordinate meaning increased. Results suggest that, while automatic processing occurs in both hemispheres, only the left hemisphere engages in controlled processing of ambiguous word meanings. In addition, the present results support the idea that the right hemisphere has a special role in ambiguity resolution and that the right hemisphere lexicon possesses a richer endowment than earlier thought.     

Chronic sweet intake lowers pain thresholds without changing brain mu- or delta-opiate receptors

Sprague-Dawley rats drank sweetened (3% dextrose + 0.144% saccharin, w/v) or unflavored water for 18 days and subsequent pain reactivity was assessed using a hot plate. Compared to the rats that consumed unflavored water, the rats that consumed sweet water responded more quickly on the hot plate indicating that their threshold for pain was lowered. Another group of rats given identical exposure to the fluids had their brains prepared for measuring opiate receptor binding using the delta-receptor ligand [3H]D-Ala-D-Leu-enkephalin ([3H]DADLE) and the mu-receptor selective ligand [3H]Tyr-D-Ala-Gly-MePhe-Gly-ol ([ 3H]DAGO). Binding of these opiates to mu- and delta-receptors in the cerebral cortex, striatum, hippocampus, hypothalamus, brain stem, and remaining brain regions was the same for the rats that drank sweet fluids and those that drank unflavored water. These findings suggest that drinking sweet fluids lowers pain thresholds but does not alter mu- and delta-receptors.     

Interactions between area and numerosity

Summary The concept of filled area, i.e. the impressionistic ensemble of parts of a stimulus field occupied by dots, is used to account for various kinds of numerosity illusions due to perceptual interaction between a number of dots and their spatial arrangement. A measure of filled area is derived from a model for the perceptual clustering of dots on the basis of relative proximity. It is shown that the quantified concept of filled area successfully predicts illusion data from earlier studies. Subsequently, a two-alternatives forced-choice numerosity experiment is reported, the data of which gave further evidence of the predictive power of the filled-area hypothesis. Our approach is discussed with respect to spatial features of dot stimuli that might be in rivalry with the filled-area factor in numerosity-estimation tasks.     

Effects of facial attractiveness and gender on causal attributions of managerial performance

The present study examined the effect of facial attractiveness and gender on raters' evaluations of and explanations for managerial performance. Results showed attractiveness to be a potential liability for both males and females. Good performance of attractive females was more likely than that of others to be attributed to luck or bias, while that of attractive males was viewed as occurring with little effort. In addition, the poor performance of attractive individuals was blamed on lack of effort (females) or lack of ability (males). Implications of these findings are discussed.An earlier version of this paper was published in the 1986 Proceedings of the Southern Management Association.     

Marriage Guidance Training and the Trainee's Own Marriage: A Prospective Study

Twenty trainees and 18 partners took part in a study of the effects of a marriage guidance training programme on their own marriage. Changes were assessed in two ways: retrospectively ('perceived' changes as assessed following training) and prospectively (changes calculated by comparing scores obtained before training and those obtained after training). For most dimensions there was little correspondence between 'perceived' change and 'calculated' change. This has important methodological implications, which are discussed. The 'calculated' change indicated poorer marital adjustment following training. The trainees' scores suggested that they had become less 'abasing' and less 'nurturant' towards their partners; also that they had more disagreements about 'philosophy of life' and 'dealing with in-laws'. Their comments suggested that a number of the trainees had become more analytical of their own marriages, and that training had heightened their awareness of their own needs and individuality.     

Gender differences in friendship patterns

The same-sex and opposite-sex friendship patterns of men and women students from two first-year psychology classes at the University of Waikato in New Zealand were examined. A friendship questionnaire previously used in the United States of America was administered to compare results of the two cultures. Findings from this study support American research suggesting that women are more intimate and emotional in their same-sex friendships than men, and tend to place a higher value on these friendships than men do. In accordance with findings of the American sample, New Zealand women emphasized talking, emotional sharing, and discussing personal problems with their same-sex friends, and men showed an emphasis on sharing activities and doing things with their men friends. Differences between the American and New Zealand samples were shown for men in the number of friends and the intimacy levels of these friendships. New Zealand men preferred numerous but less intimate same-sex friends, while women (as in the United States) showed a preference for a few, close, intimate same-sex friends. Men, in contrast to women, derived emotional support and therapeutic value more from their opposite-sex relationships than their same-sex friendships. Finally, more men than women stated they would not cancel an engagement with an opposite-sex friend in order to go out with a same-sex friend. Results are interpreted as suggesting a need for changes in the current socialization process of males who are taught to repress their emotions and form rather less intimate and possibly less beneficial same-sex friendships than women.     

Two forms of minority-group test bias as psychometric artifacts with an animal model (Rattus norvegicus)

Controversy abounds over attributing group differences on tests to nature, nurture, or test bias. Limitations of correlational sampling from natural populations necessitate experimental methods to resolve underlying issues. In classical psychometrics test items are selected from a larger item pool through analysis of item responses in a sample of subjects. Rats of six inbred strains (n = 366) were tested in multiple mazes to provide a large item pool. Six populations were created, each with differing proportions of each strain. Items selected through independent item analyses within each population yielded six tests. An independent cross-validation sample (n = 146) provided scores on all six tests. This sample was also tested in another set of maze problems defined as the criterion to be predicted. Strain means and intrastrain predictive validities for the six tests varied with strain representation in the population used for item selection (p less than .001). Conventional item-selection procedures clearly produced two forms of minority test bias.     

Confidence in judgments based on incomplete information: An investigation using both hypothetical and real gambles

This study assessed how confidence in judgments is affected by the need to make inferences about missing information. Subjects indicated their likelihood of taking each of a series of gambles based on both probability and payoff information or only one of these sources of information. They also rated their confidence in each likelihood judgment. Subjects in the Explicit Inference condition were asked to explicitly estimate the values of missing information before making their responses while subjects in the Implicit Inference condition were not. The manner in which probability information was framed was also manipulated. Experiment 1 employed hypothetical gambles and Experiment 2 employed gambles with real money. Expressed likelihood of taking gambles was higher when probability was phrased in terms of '% chance of winning' rather than '% chance of losing', but this difference was somewhat less with real gambles than with hypothetical gambles. Confidence ratings in each experiment were actually higher on incomplete information trials than on complete information trials in the Explicit Inference condition. Results were related to the general issue of confidence in judgments.     

Individual differences in reverse Hindsight bias: I never thought something like chernobyl would happen. Did I?

Hindsight bias was studied in the context of the accident in the Chernobyl nuclear power plant, which took place on April 26th 1986. An individual difference factor which relates to the motivation to process information, need for cognition, was expected to moderate the occurrence of hindsight bias. Probability estimates of many casualties due to the use of nuclear power in The Netherlands were obtained from 212 individuals two months before the accident in Chernobyl. These estimates were compared with similar estimates made in hindsight by the same individuals five months after the accident. Loglinear Analyses reveal a systematic hindsight bias. However, the direction of the bias was contrary to expectations. In hindsight, individuals gave lower probabilities than they actually did two months before the Chernobyl accident. These results reveal a reverse hindsight bias. As hypothesized, need for cognition moderates hindsight bias: individuals low and medium in need for cognition express a systematic reverse hindsight bias, while individuals high in need for cognition do not. High need for cognition individuals also show higher literal consistency between the two measurements, which supports a memory explanation of the moderating effect of need for cognition.