Evaluation of living conditions of free-ranging animals by automated chronobiological analysis of behavior

A biorhythmical method has been developed to assess behavior patterns and to evaluate the living conditions of animals that can be applied also to humans. All kinds of continuous and equidistant long-term recordings of behavior are suitable for this method. Time functions from an automatic telemetry system (ETHOSYSII) were analyzed macroscopically (comparison of daily levels) and microscopically (autocorrelation function and power spectral analysis). Degrees of functional coupling (DFCs) were calculated to identify and evaluate disturbances in behavior. Hierarchic frequency tuning of complex rhythmic functions of behaviors, leads primarily to period lengths that are synchronized with the 24-h period. DFCs, a measure of harmony between internal rhythms and the external 24-h period, were found to be high in well-adapted, healthy, and undisturbed individuals but were lowered during periods of adaptation, sickness, or social interaction. Specific stress conditions could be identified and evaluated in several species, under various conditions, using these biorhythmic analyses.     

How owls structure visual information

Recent studies on perceptual organization in humans claim that the ability to represent a visual scene as a set of coherent surfaces is of central importance for visual cognition. We examined whether this surface representation hypothesis generalizes to a non-mammalian species, the barn owl (Tyto alba). Discrimination transfer combined with random-dot stimuli provided the appropriate means for a series of two behavioural experiments with the specific aims of (1) obtaining psychophysical measurements of figure–ground segmentation in the owl, and (2) determining the nature of the information involved. In experiment 1, two owls were trained to indicate the presence or absence of a central planar surface (figure) among a larger region of random dots (ground) based on differences in texture. Without additional training, the owls could make the same discrimination when figure and ground had reversed luminance, or were camouflaged by the use of uniformly textured random-dot stereograms. In the latter case, the figure stands out in depth from the ground when positional differences of the figure in two retinal images are combined (binocular disparity). In experiment 2, two new owls were trained to distinguish three-dimensional objects from holes using random-dot kinematograms. These birds could make the same discrimination when information on surface segmentation was unexpectedly switched from relative motion to half-occlusion. In the latter case, stereograms were used that provide the impression of stratified surfaces to humans by giving unpairable image features to the eyes. The ability to use image features such as texture, binocular disparity, relative motion, and half-occlusion interchangeably to determine figure–ground relationships suggests that in owls, as in humans, the structuring of the visual scene critically depends on how indirect image information (depth order, occlusion contours) is allocated between different surfaces. Electronic Publication     

Acculturation and Cognitive Performance of Migrant Children in The Netherlands

Acculturative strategies and cognitive acculturation were studied among 118 Dutch migrant children (age: 7–12 years). Both an exploratory factor analysis and a Linear Logistic Test Model analysis provided evidence for the bipolar unidimensionality of Berry's four acculturation strategies; integration constituted one pole and assimilation, separation, and marginalization the other. Integration was by far the most popular strategy. Cognitive performance was measured by the Snijders-Oomen Nonverbal Intelligence Test, school report measures, and a computer-assisted choice reaction-time measure. A good fit was found for a structural model that postulated cognitive acculturation as the latent variable linking background measures (i.e. acculturation strategy, second language usage, age, and gender) to the cognitive measures. Relationships between background variables and cognitive performance were stronger in the first than in the second generation. Both older children and children who favour an integration strategy showed a higher degree of cognitive acculturation.     

The Iowa Infant Feeding Attitude Scale: Analysis of Reliability and Validity1

Development of the Iowa Infant Feeding Attitude Scale (IIFAS) is described. In Study 1, a set of 17 items was selected on the basis of responses by 125 postpartum women. Analyses of the reliability and validity were then conducted. In Study 2, these analyses were replicated using data from an independent sample of 130 postpartum women. Study 3 involved an analysis of the ability of scores on the IIFAS to predict duration of breast-feeding among a sample of 725 women who had initiated that method of feeding their babies while in the hospital. Limitations of this research and possible future uses of the IIFAS in studies addressing the determinants and consequences of infant-feeding attitudes are discussed.     

Motion aftereffect of combined first-order and second-order motion

When, after prolonged viewing of a moving stimulus, a stationary (test) pattern is presented to an observer, this results in an illusory movement in the direction opposite to the adapting motion. Typically, this motion aftereffect (MAE) does not occur after adaptation to a second-order motion stimulus (i.e. an equiluminous stimulus where the movement is defined by a contrast or texture border, not by a luminance border). However, a MAE of second-order motion is perceived when, instead of a static test pattern, a dynamic test pattern is used. Here, we investigate whether a second-order motion stimulus does affect the MAE on a static test pattern (sMAE), when second-order motion is presented in combination with first-order motion during adaptation. The results show that this is indeed the case. Although the second-order motion stimulus is too weak to produce a convincing sMAE on its own, its influence on the sMAE is of equal strength to that of the first-order motion component, when they are adapted to simultaneously. The results suggest that the perceptual appearance of the sMAE originates from the site where first-order and second-order motion are integrated.     

Axiomatic foundations of the Marxian Theory of Value

The aim of the present paper is to provide a logical reconstruction of the Marxian Theory of Value. This reconstruction is based upon the concept of abstract as opposed to that of homogeneous labor. Abstract labour is a social relation that holds in a market economy, (at least) whenever the profit rate is uniform; it consists in a comparison of the different labors through the exchange relationship. The author proved in a different place (see García de la Sienra, 1987) that there exists a mathematical representation of abstract labor which is unique up to similarity transformations. The existence of this function — which is none other than the value function — is the basis of the present axiomatization, which includes detailed reconstructions of two of the most important models of the theory.     

Young Muslim Women in France: Cultural and Psychological Adjustments

Even though France has experienced increasing and inevitable feminization in its immigrant population since 1974, research has tended to ignore the role of immigrant women, especially Muslim women, in the migration process. Public attention has been diverted by concern over such relatively marginal issues as the headscarf affair, and insufficient attention has been paid to the important role Muslim women play in France, especially those coming from Algeria. These women function as cultural mediators between the traditional culture of the sending country and the modern one of the host country. They see themselves as both tradition-bearers and integration proponents. The demands of immigration have given rise to the growth and development of different leaders, among them cultural mediators seeking a bridge between Islam and modernity, economic mediators seeking to establish women in the media and as entrepreneurs, and political mediators who seek access to power at the local level for the immigrants. These new mediators will eventually shape a new generation of female actors very far from the traditional countries of origin, although for the time being they still suffer from the inequality of rights for women and chances in their overall social life.     

An automated technique for the study of cyclic fluctuations in sexual motivation in an avian species

Diurnal fluctuations in sexual behavior occur in freely interacting pairs of male and female birds. These fluctuations are difficult to interpret because they may reflect fluctuations in the motivation of the male, the motivation of the female, or both. A method was developed to study the sexual motivation of male Japanese quail in response to a standard stimulus. Sexual behavior was elicited by a taxidermic model of a female quail in a squatting posture. Sensors beneath and in the back of the model served to detect when the male mounted and made cloacal contact with the model. The technique allowed continuous recording of male sexual behavior under standard conditions. When males were maintained on a photoperiod with lights on at 0600 h and off at 2200 h, sexual behavior peaked in the early afternoon, with a secondary peak just before lights-out.