The roleof availabilityinthe estimationof nationalpopulations

In two parallel experiments, conducted 17 months apart, we examined the relations among population estimates, availability, and media coverage of the 100 countries with populations of 4 million or more. The results were consistent with the main hypothesis, that availability influences population estimates. Specifically, we found that (1) rated knowledge of each country (our measure of availability) was strongly correlated with estimated population for that country; (2) rated knowledge was more strongly correlated with estimated population than were other plausible predictors, such as land area; (3) a strong partial correlation between rated knowledge and estimated population remained even after true population and true land area were partialed out; and (4) longitudinal changes in rated knowledge predicted longitudinal changes in estimated population. Also as hypothesized, media coverage was positively related to availability and to population estimates. Further, we found that population estimates, rated knowledge, and amount of media coverage that each country received were very stable over the year-and-a-half period. These results led us to consider when availability is most likely to be relied upon heavily in quantitative estimation and how it may be integrated with other knowledge to derive quantitative estimates.     

Biological basis of the stress response.

Chronic, as well as acute emotional arousal, is a consequence of various types of social interaction, i.e., those between mother and infant and between controlling dominant and less effective subordinate. The neurohumoral accompaniments of this social stress include the sympathetic adrenal medullary and hypothalamic pituitary adrenal responses. A common ensuing pathophysiological state involves a chronic increase of blood pressure. Although Selye's General Adaptation Syndrome presupposed the same response to a variety of stimuli; recent work shows that specific perceptions of control result in different patterns of neuroendocrine activation. A challenge perceived as easy to handle will elicit an active coping response and release of the neurosympathetic system's norepinephrine. Testosterone will rise as the subject savors success. With increasing anxiety this active coping shifts to a more passive mode and the behavior becomes less assured as the animal loses control. The norepinephrine/epinephrine ratio decreases as epinephrine, prolactin, renin and fatty acids rise. As the outcome becomes still less certain and distress grows, adrenocorticotropic hormone and cortisol levels arise. Thus, the effort required on the one hand and the degree of frustration conflict and uncertainty on the other, determine the ratio of catecholamines to corticoids. With severe emotional trauma, brain dysfunction may occur. These effects can be lasting, and corticoids paradoxically return to normal as the behavior changes to that of post-traumatic stress disorder. Repression and denial set in and the organism responds with decreased concern of impaired attachment and increased irritability.     

Biological basis of the stress response

Chronic, as well as acute emotional arousal, is a consequence of various types of social interaction, i.e., those between mother and infant and between controlling dominant and less effective subordinate. The neurohumoral accompaniments of this social stress include the sympathetic adrenal medullary and hypothalamic pituitary adrenal responses. A common ensuing pathophysiological state involves a chronic increase of blood pressure. Although Selye’s General Adaptation Syndrome presupposed the same response to a variety of stimuli; recent work shows that specific perceptions of control result in different patterns of neuroendocrine activation. A challenge perceived as easy to handle will elicit an active coping response and release of the neurosympathetic system’s norepinephrine. Testosterone will rise as the subject savors success. With increasing anxiety this active coping shifts to a more passive mode and the behavior becomes less assured as the animal loses control. The norepinephrine/epinephrine ratio decreases as epinephrine, prolactin, renin and fatty acids rise. As the outcome becomes still less certain and distress grows, adrenocorticotropic hormone and cortisol levels arise. Thus, the effort required on the one hand and the degree of frustration conflict and uncertainty on the other, determine the ratio of catecholamines to corticoids. With severe emotional trauma, brain dysfunction may occur. These effects can be lasting, and corticoids paradoxically return to normal as the behavior changes to that of post-traumatic stress disorder. Repression and denial set in and the organism responds with decreased concern of impaired attachment and increased irritability.     

Visual search for simple volumetric shapes

Five experiments measured reaction time (RT) to detect the presence or absence of a simple volumetric shape (target) dependent on the number of display items (distractors) and their depicted three-dimensional (3-D) orientation. Experiments 1–4 examined every pairwise combination of two different simple volumetric shapes in two 3-D orientations. Conditions exhibiting “pop-out” could be predicted by differences in their two-dimensional (2-D) features. Conditions in which search was slower support previously found search asymmetries for particular 2-D features. When the distractors were a mixture of the other shapes in the same 3-D orientation, search was serial, except when the target had a curved principal axis (Experiment 5). The results suggest that these simple volumetric shapes are not processed preattentively.     

A new method of monitoring motor activity in baboons

Movement activity of a normal baboon and of a baboon with induced Parkinsonism by unilateral administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was recorded by the Walter Reed Activity Monitor (or actigraph). Mean activity in the lesioned baboon was 41% less than that of the nonlesioned baboon measured over a 14-day period. In addition, the daily maximum activity value was significantly less in the MPTP-treated baboon. Moreover, resting and sleeping periods were 30% greater in the lesioned animal. The akinesia and resting and sleeping periods were displayed by the lesioned baboon throughout the day, whereas the control baboon showed them only at night. The data representing summarized movement activity are in accordance with observations of bradykinesia, hypokinesia, and akinesia of the MPTP-treated baboon. The actigraph was well tolerated by the animal because its small size and weight made it largely unobtrusive. We suggest that the actigraph is an appropriate device for measuring motor activity in nonhuman primates.     

Use of speech-modulated noise adds strong “bottom-up” cues for phonemic restoration

When deleted segments of speech are replaced by extraneous sounds rather than silence, the missing speech fragments may be perceptually restored and intelligibility improved. This phonemic restoration (PhR) effect has been used to measure various aspects of speech processing, with deleted portions of speech typically being replaced by stochastic noise. However, several recent studies of PhR have used speech-modulated noise, which may provide amplitude-envelope cues concerning the replaced speech. The present study compared the effects upon intelligibility of replacing regularly spaced portions of speech with stochastic (white) noise versus speech-modulated noise. In Experiment 1, filling periodic gaps in sentences with noise modulated by the amplitude envelope of the deleted speech fragments produced twice the intelligibility increase obtained with interpolated stochastic noise. Moreover, when lists of isolated monosyllables were interrupted in Experiment 2, interpolation of speech-modulated noise increased intelligibility whereas stochastic noise reduced intelligibility. The augmentation of PhR produced by modulated noise appeared without practice, suggesting that speech processing normally involves not only a narrowband analysis of spectral information but also a wideband integration of amplitude levels across critical bands. This is of considerable theoretical interest, but it also suggests that since PhRs produced by speech-modulated noise utilize potent bottom-up cues provided by the noise, they differ from the PhRs produced by extraneous sounds, such as coughs and stochastic noise.     

Two approaches to the formalisation of defeasible deontic reasoning

This paper compares two ways of formalising defeasible deontic reasoning, both based on the view that the issues of conflicting obligations and moral dilemmas should be dealt with from the perspective of nonmonotonic reasoning. The first way is developing a special nonmonotonic logic for deontic statements. This method turns out to have some limitations, for which reason another approach is recommended, viz. combining an already existing nonmonotonic logic with a deontic logic. As an example of this method the language of Reiter's default logic is extended to include modal expressions, after which the argumentation framework in default logic of [20, 22] is used to give a plausible logical analysis of moral dilemmas and prima facie obligations.An earlier version of this article was written while the author was working at the Department of Computing, Imperial College London, supported by ESRC/MRC/SERC Joint Council Initiative Project G9212036. Work on the present version was supported by a research fellowship of the Royal Netherlands Academy of Arts and Sciences, and by Esprit WG 8319 Modelage. I thank one of the referees for his interesting comments. Also, many thanks are due to Marek Sergot for valuable discussions on the topic of this paper.     

Helping Groups Determine Their Most Accurate Member: The Role of Outcome Feedback1

One of the difficulties groups have when making quantitative judgments is determining the relative quality of members’ inputs. Outcome feedback was investigated as a method for improving the ability of groups to identify their most accurate member. Results indicate that groups given outcome feedback were better at identifying their best member than were groups that practiced without feedback. This occurred even though the same individual was seldom the most accurate across items. However, groups given feedback were not as accurate as their best member any more often. This suggests that groups given feedback are learning how to discriminate valid from invalid cues, but are not using this information consistently when making their group estimates.     

Psychiatric sequelae of low birth weight at 6 years of age

The study examined the association between low birth weight (LBW) (2,500 g) and attention deficit hyperactivity disorder (ADHD) in two socioeconomically disparate populations. LBW and normal birth weight (NBW) children from the 1983 to 1985 newborn lists of an urban and a suburban hospital in Southeast Michigan were randomly selected. A total of 823 children, 473 LBW and 350 NBW, participated. Data were gathered in 1990 to 1992, when the children were 6 to 7 years of age. The National Institute of Mental Health Diagnostic Interview Schedule for children—Parent version (DISC-P) was used to elicit information on DSM-III-R diagnoses of simple phobia, overanxious, separation anxiety, oppositional defiant, and ADHD. Teachers' ratings of behavior problems were obtained. LBW was associated with ADHD but not with childhood anxiety disorders or oppositional defiant disorder. The association was stronger in the urban than in the suburban population. Data from teachers' ratings revealed an association between LBW and attention problems. The prognostic significance of the observed psychopathology at 6 years of age requires follow-up assessment as the children mature.This research was supported by NIMH research grant MH-44586 and NIMH Research Scientist Development Award MH-00380 to Dr. Breslau.