Concave and convex phases in ambiguous figures showing colour shifts. Mach's figure and the AMBEGUJAS phenomenon

Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases.     

A MODERN LOOK AT THE ORIGIN OF THE UNIVERSE

Abstract. In what follows, I review the modern theory of the origin of the universe as astronomers and physicists are coming to understand it during the last decades of the twentieth century. An unexpected discovery of this study is that the story of "cosmogenesis" cannot be completely told unless we understand the fundamental nature of matter, space, and time. In the context of modern cosmology space has become not only the bedrock (so to speak) of our physical existence, it may yield a fuller understanding of the universe itself.     

Regional cerebral blood flow and verbal memory after chronic exposure to organic solvents

Regional cerebral blood flow (rCBF; 133Xe-inhalation method) was investigated in 32 industrial workers (age: 51 +/- 9 years) who had been exposed to organic solvents during an average of 24.5 years. The measurements were made at rest and during learning of associated word pairs. The resting flow level was 17% lower than expected for normal subjects of similar age and the activation-induced changes of rCBF during the test lacked the frontal activation normally seen. Significant correlations between age, length of exposure, and rCBF level were found. In order to control for the age factor, results were also calculated from two subgroups of similar age but with very different levels of exposure (13 and 31 years of average exposure). The two groups differed only slightly in resting rCBF. A marked difference was, however, seen during activation, with significant post-central flow increases recorded in the lower-exposed group only. The results indicate the potential of the rCBF method for elucidating functional cortical changes related to neurotoxic effects of organic solvents.     

Belief revision,epistemic conditionals and the Ramsey test

Epistemic conditionals have often been thought to satisfy the Ramsey test (RT): If A, then B is acceptable in a belief state G if and only if B should be accepted upon revising G with A. But as Peter Gärdenfors has shown, RT conflicts with the intuitively plausible condition of Preservation on belief revision. We investigate what happens if (a) RT is retained while Preservation is weakened, or (b) vice versa. We also generalize Gärdenfors' approach by treating belief revision as a relation rather than as a function.In our semantic approach, the same relation is used to model belief revision and to give truth-conditions for conditionals. The approach validates a weak version of the Ramsey Test (WRR) — essentially, a restriction of RT to maximally consistent belief states.We prove that alternatives (a) and (b) are both consistent, but argue that (b) is philosophically more promising. Gärdenfors' belief-revision axioms are compatible with WRR together with RT from left to right: the only direction of the test that is defensible on intuitive grounds.An earlier version of this paper was presented at the conference on the dynamics of knowledge and belief at Lund University, 24–26 August 1989. We wish to thank Sven Danielsson, Peter Gärdenfors, Sören Halldén, David Makinson, Hugh Mellor, Michael Morreau, Nils-Eric Sahlin and Brian Skyrms for their very helpful suggestions and remarks. We are also grateful for thought-provoking criticism and comments from two anonymous referees.     

THE EQUIVALENCE COEFFICIENT AND THE KUDER-RICHARDSON COEFFICIENT 20

H enrysson , S. The equivalence coefficient and the Kuder-Richardson coefficient 20. Scand. J. Psychol ., 1962, 3 , 40–46.—The relation between the equivalence coefficient and the Kuder-Richardson coefficient 20 is discussed. Formulas, tables and graphs of the difference between the two coefficients are given. In most cases the difference between the two coefficients will be rather small.     

A PARADOX IN THE PERCEPTION OF LUMINANCE GRADIENTS. I

Under certain conditions subjects looking at a luminance gradient report a physically darker part of the gradient to be brighter than an adjacent area of higher luminance. This brightness paradox was studied in a series of experiments using a magnitude estimation method. The main results were that both the changing sign of the second derivative of the luminance function (Mach's hypothesis) and the higher or lower luminance of an adjacent area (McDougall's drainage theory) are critical conditions for the appearance of the paradox. In the present study none of these conditions per se resulted in a brightness paradox.     

Personality dimensions in patients with sleep-apnea syndrome: comparison with narcolepsy

Personality measures of Anxiety-Neuroticism, Extraversion and Socialization obtained from self-report questionnaires were studied in a group of sleep-apnea patients (15 males, 5 females), and compared with results from a normal control group (63 males, 21 females) and a group of narcoleptic patients (17 males, 32 females). Sleep-apnea patients were significantly higher in Anxiety-Neuroticism and slightly higher in Extraversion than controls. Although the main symptom, i.e. excessive daytime sleepiness, of sleep-apnea and narcoleptic patients is similar, there were distinct differences in pattern of personality measures. Sleep-apnea patients were lower in Anxiety-Neuroticism and higher in Extraversion. Thus, increased sleepiness alone did not induce uniform changes in personality traits in the two patient groups. It is suggested that the particular personality profile of the sleep-apnea patients is secondary to increased psychosocial strain and coping strategies to keep awake. In contrast, the high Somatic Anxiety scores and low Socialization scores in the narcoleptic group are assumed to reflect a constitutional lability which also involves autonomic and sleep functions.     

FACTOR ANALYSIS OF A NEUROTICISM INVENTORY

The Lidvall neuroticism inventory is comprised of 25 questions referring to symptoms presumed to be connected with manifest neurotic anxiety. It was presented to 377 persons, an unscreened group with respect to neurotic symptoms, and a factor analysis with rotation to simple structure was performed.—Four factors could be identified: (1) manifest neurotic anxiety, (2) neurotic difficulties in interpersonal relations, (3) neurasthenic symptoms and (4) obsessive-compulsive symptoms. The factor scales were correlated with Neuroticism and Extraversion in MPI. Neuroticism was shown to be a heterogeneous factor. The correlation between Factor (2) and Extraversion was high.