On the transmission of partial information: inferences from movement-related brain potentials.

Results are reported from a new paradigm that uses movement-related brain potentials to detect response preparation based on partial information. The paradigm uses a hybrid choice-reaction go/nogo procedure in which decisions about response hand and whether to respond are based on separate stimulus attributes. A lateral asymmetry in the movement-related brain potential was found on nogo trials without overt movement. The direction of this asymmetry depended primarily on the signaled response hand rather than on properties of the stimulus. When the asymmetry first appeared was influenced by the time required to select the signaled hand, and when it began to differ on go and nogo trials was influenced by the time to decide whether to respond. These findings indicate that both stimulus attributes were processed in parallel and that the asymmetry reflected preparation of the response hand that began before the go/nogo decision was completed.     

Nifedipine blocks retention of a visual discrimination task in chicks.

Reports that the dihydropyridine Ca2+ channel antagonists may facilitate memory led to the present study of the behavioral effects of nifedipine. Ninety-two 4-day-old male chicks received 0, 100 nM, 100 microM, or 10 mM nifedipine. Drugs were administered in volumes of 2 microliters into the fourth cerebral ventricle 5 min before training on a visual discrimination task. Nifedipine did not produce any detectable changes in behavior during acquisition trials. Retention, however, was impaired 24 h after training in the 100 nM and 100 microM nifedipine-treated chicks, which made significantly more errors than controls. Nifedipine did not affect the amount of time required to complete the task. No effects on body weight gain were detected, suggesting that the memory impairment was not due to a change in feeding behavior. These data are discussed in terms of the role of calcium-dependent processes in memory.     

Attentional demands of processing shape in three-dimensional space: evidence from visual search and precuing paradigms.

The hypothesis that representation of projective shape is preattentive whereas representation of objective shape in three-dimensional space requires allocation of attention was tested in 2 visual search and 2 precuing experiments. In the visual search experiments, the slope for projective shape search was expected to approach 0 and that for objective shape search was expected to be a positive monotonic function of set size. In the precuing experiments, the effects of precuing were expected to be largely limited to the task requiring representation of objective shape. The overall pattern of results conformed to expectations. The findings are interpreted in the context of a model of shape-at-a-slant processing set out by Epstein and Lovitts (1985) and Epstein and Babler (1989, 1990).     

The associative basis of contingent color aftereffects.

According to a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimulus (grids) become associated with color. Contrary to this interpretation are reports that simple forms cannot be used to elicit illusory color and that the ME is not degraded by decreasing the grid-color correlation. The present results indicate: (a) Form stimuli can contingently elicit color aftereffects; (b) even a non-patterned stimulus--the lightness of a frame surrounding a colored area--can contingently elicit color aftereffects; (c) this frame lightness-contingent aftereffect, like the ME, persists for at least 24 hr; and (d) the frame lightness-contingent aftereffect can be used to demonstrate that correlational manipulations affect the ME, as they affect other types of conditional responses.     

Mentality and causality

I am grateful to John Bickle, Jaegwon Kim, Brian McLaughlin, and, most especially, to my colleague, Alfred Mele, for much helpful discussion on the topic of intentional causation.     

Ethical Issues in Counselling and Pastoral Care

The historical and contemporary context of pastoral care and counselling within the judaeo/Christian tradition is reviewed. Three kinds of pastors who use counselling in their work - Christian, specialist, and generic - are identified and the ethical problems of their positions clarified. The ethical principles of autonomy, beneficence, non-maleficence and justice are applied to the counselling work of pastors. Theology's definition of various ethical levels, and the impact of these upon the professional ethics of pastoral carers and counsellors, are explored, and some conclusions for the future drawn.     

Perception of complex geometric figures in chimpanzees (Pan troglodytes) and humans (Homo sapiens): analyses of visual similarity on the basis of choice reaction time.

In a conditional-discrimination task (matching-to-sample), we assessed similarities among figures consisting of 2 elemental figures through the choice reaction time, nonmetric multidimensional scaling, and hierarchical cluster analysis data from chimpanzees (Pan troglodytes) and humans (Homo sapiens). Humans also rated similarities among figures. The results of the 3 experiments clearly indicated that the reaction time data obtained from chimpanzees' performances were useful measures of the similarities among figures. The results suggested that chimpanzees and humans perceived the complex figures similarly. The outer-contour elements were perceived most dominantly by both species, and the straight-line elements were perceived least dominantly. Both species showed the same perceptual hierarchy or dominance among perceptual categories, as determined by the similarity of simple elements, on the basis of transformational invariances.     

Gender and temporal differences in identifying sources of stress

Much of the methodology in stress research focuses on stress manifestation and organismic reactions to life’s crises. In contrast, the present study sought to identify the major sources of stress and the nature of those sources. The results revealed a consistent pattern in high and low stressors throughout the 3-year period of the study, and differences only of intensity between males and females, not type of stress. Except for individuals’ temporal variations in critical events, the highest stressors for the groups were external, primarily financial and time management. Internal sources, such as personal relationships and self-absorption, were typically the lowest concerns. Everyday problems arising from current life styles seem to be significant sources of stress.     

Prejudice and behavior: A review

Originally it was thought that prejudiced intergroup attitudes were very closely related to negative intergroup behavior. More recently, empirical studies reveal a weak and inconsistent relationship, that discriminatory intergroup behavior is therefore largely determined by situational factors, and that it is relatively independent of an individual’s attitudes. A detailed review of this research, however, suggests that the relationship between prejudice and behavior may be much more consistent than has been thought. Moreover, although the relationship is usually not very powerful, most research has involved methodological inadequacies which would have inappropriately depressed it. Finally, it is noted that, for negative intergroup behavior to be situationally determined, does not exclude a strong relationship between it and prejudiced attitudes.     

Motion perception and aging.

The authors used a correlated motion paradigm to investigate the effects of aging and gender on motion sensitivity. In 2 experiments with a total of 50 elderly and 50 young subjects, motion thresholds were significantly higher for elderly women. The correlated motion signal, which was embedded in random motion, may have been coherent to subjects in much the same way a form is in Witkin's Embedded Figures Test (EFT). In Experiment 2, EFT scores were obtained. A significant positive relationship between motion thresholds and EFT performance was found within each age group. Although gender-related perceptual style differences may contribute to motion perception effects, the authors argue that a common neural factor contributes to performance on both the EFT and the correlated motion task.