Decidability for branching time

The species of indeterminist tense logic called Peircean by A. N. Prior is proved to be recursively decidable. To the memory of Ivo Thomas     

Weapons and Eye Contact as Instigators or Inhibitors of Aggressive Arousal in Police-Citizen Interaction1

A field experiment was conducted with police officers during the normal course of their traffic patrol duties. The purpose was to determine whether the presence of holstered weapons and mirror sunglasses affected the degree of aggressiveness expressed nonverbally, and reported on a mood scale by citizens halted for an information check (neutral condition) or in order to be given a traffic ticket (negative condition). Results indicated that subjects in the negative condition both expressed and reported more aggressivity when the police officer wore a weapon than when no weapon was visible. The use of sunglasses had no effect on aggressivity but resulted in the officer's being perceived more negatively, though he was not perceived more negatively when he wore a weapon. No sex differences in expressed or reported aggressivity were obtained, although some sex differences on measures of secondary interest did occur. The implications of these findings for research on the “weapons effect” and on policy regarding the visibility of police weapons and the wearing of sunglasses by police officers are discussed.     

The degree of control exerted by phobic and non-phobic verbal stimuli over the recognition behaviour of phobic and non-phobic subjects

Four groups of subjects comprised of one control group, two analogue phobic groups and one clinical phobic group were exposed to a dichotic listening experiment in which they were required both to shadow one message to the exclusion of the other and recognize the occurrence of target words appearing in both the attended and rejected messages. Target words were either phobic-relevant or neutral. It was found that the clinical phobic group recognized significantly more target words than any of the other groups. This difference was due to their superior recognition of phobic-relevant targets from the rejected message. The results were interpreted within a combined framework of Staats's (1968, 1975) social behaviour theory and the Rescorla and Wagner (1972) model of classical conditioning.     

Matching since Baum (1979).

Data from recent studies employing concurrent variable-interval schedules are reviewed. Subject species employed in different experiments have included rats, pigeons, and humans, and reinforcers have varied from food and shock avoidance to points exchangeable for money. Undermatching (a greater preference for the schedule of the concurrent pair that delivers the lower rate of reinforcement than the Matching Law predicts) has been preponderant in recent studies, irrespective of whether behavior has been measured in terms of response ratios or time allocation, with the possible exception of data produced by human subjects. Little difference in the degree of undermatching exhibited by response and time measures has been found, except in the results from a single laboratory, in which time-allocation measures have tended to undermatch less than response measures. Procedural features, such as type of manipulandum used and changeover delay, seem to have little effect on the degree of undermatching exhibited, but asymmetrical response manipulanda (such as lever and key) for the different concurrent schedules, or other asymmetries in the experimental situation, show up clearly in bias measures, in a manner consistent with previous analyses.     

Readability of prescription drug labels by older and younger adults

This experiment investigated the readability of medication labels using various combinations of fonts, sizes, and weights of print. Older and younger adult reading speeds and error rates for different print types were compared for both bottle and flat labels. Findings of the study indicated significant differences in reading speed, error rates, and subjective evaluations for print characteristics investigated. Furthermore, the effects of these print characteristics varied for different age groups. Implications of these findings for the design of medication labels for older adults are discussed.     

The hippocampus, space, and viewpoints in episodic memory

A computational model of how single neurons in and around the rat hippocampus support spatial navigation is reviewed. The extension of this model, to include the retrieval from human long-term memory of spatial scenes and the spatial context of events is discussed. The model explores the link between spatial and mnemonic functions by supposing that retrieval of spatial information from long-term storage requires the imposition of a particular viewpoint. It is consistent with data relating to representational hemispatial neglect and the involvement of the mammillary bodies, anterior thalamus, and hippocampal formation in supporting both episodic recall and the representation of head direction. Some recent behavioural, neuropsychological, and functional neuroimaging experiments are reviewed, in which virtual reality is used to allow controlled study of navigation and memory for events set within a rich large-scale spatial context. These studies provide convergent evidence that the human hippocampus is involved in both tasks, with some lateralization of function (navigation on the right and episodic memory on the left). A further experiment indicates hippocampal involvement in retrieval of spatial information from a shifted viewpoint. I speculate that the hippocampal role in episodic recollection relates to its ability to represent a viewpoint moving within a spatial framework.     

Children reorient using the left/right sense of coloured landmarks at 18-24 months

In previous studies, children disoriented in small enclosures used room shape, but not wall colours, to find hidden objects. Their reorientation was said to depend solely on a "geometric module" informationally encapsulated with respect to colour. We argue that previous studies did not fully evaluate children's use of colour owing to a bias in the enclosures' design. In this study, disoriented 18-24 month olds searched for toys in small square enclosures with two blue and two white walls. Children successfully reoriented using wall colour. This shows that they can make location judgments based on the left/right sense of the colours of adjoining landmarks. Performance was no different when symmetric colourful shapes were added to walls, but improved with asymmetric shapes which could be used without left/right judgments. The relatively poor use of colour in previous studies may be explained partly by a bias in their design, and partly by children's limited ability to discriminate the left/right sense of nongeometric features.     

Effects of discrete emotions on young children's suggestibility

Two experiments investigated the effects of sadness, anger, and happiness on 4- to 6-year-old children's memory and suggestibility concerning story events. In Experiment 1, children were presented with 3 interactive stories on a video monitor. The stories included protagonists who wanted to give the child a prize. After each story, the child completed a task to try to win the prize. The outcome of the child's effort was manipulated in order to elicit sadness, anger, or happiness. Children's emotions did not affect story recall, but children were more vulnerable to misleading questions about the stories when sad than when angry or happy. In Experiment 2, a story was presented and emotions were elicited using an autobiographical recall task. Children responded to misleading questions and then recalled the story for a different interviewer. Again, children's emotions did not affect the amount of story information recalled correctly, but sad children incorporated more information from misleading questions during recall than did angry or happy children. Sad children's greater suggestibility is discussed in terms of the differing problem-solving strategies associated with discrete emotions.     

Racial differences in birth outcomes: the role of general, pregnancy, and racism stress.

OBJECTIVE: This study examined the role of psychosocial stress in racial differences in birth outcomes. DESIGN: Maternal health, sociodemographic factors, and 3 forms of stress (general stress, pregnancy stress, and perceived racism) were assessed prospectively in a sample of 51 African American and 73 non-Hispanic White pregnant women. MAIN OUTCOME MEASURES: The outcomes of interest were birth weight and gestational age at delivery. Only predictive models of birth weight were tested as the groups did not differ significantly in gestational age. RESULTS: Perceived racism and indicators of general stress were correlated with birth weight and tested in regression analyses. In the sample as a whole, lifetime and childhood indicators of perceived racism predicted birth weight and attenuated racial differences, independent of medical and sociodemographic control variables. Models within each race group showed that perceived racism was a significant predictor of birth weight in African Americans, but not in non-Hispanic Whites. CONCLUSIONS: These findings provide further evidence that racism may play an important role in birth outcome disparities, and they are among the first to indicate the significance of psychosocial factors that occur early in the life course for these specific health outcomes.