Brightness constancy in a Ganzfeld environment

In this paper, experiments are described in which brightness constancy was studied in a Ganzfeld environment. Luminance variation by means of neutral density filters was applied to stimuli consisting of a Ganzfeld with superimposed disks. To this end, a special-purpose apparatus was constructed. Sequential dichoptical brightness matches with a reference stimulus were carried out for the disks as well as the homogeneous surround. The results of these measurements indicate that (1) besides a clear tendency toward brightness constancy, small but systematic effects of the average luminance level are present and (2) the brightness of the Ganzfeld is hardly affected by the presence of the disks. Finally, it is shown that the experimental results can be modeled adequately in terms of a concept that involves an accumulation of contrast information.     

Inter-individual differences in how presentation modality affects verbal learning performance in children aged 5 to 16

This study examines inter-individual differences in how presentation modality affects verbal learning performance. Children aged 5 to 16 performed a verbal learning test within one of three presentation modalities: pictorial, auditory, or textual. The results indicated that a beneficial effect of pictures exists over auditory and textual presentation modalities and that this effect increases with age. However, this effect is only found if the information to be learned is presented once (or at most twice) and only in children above the age of 7. The results may be explained in terms of single or dual coding of information in which the phonological loop is involved. Development of the (sub)vocal rehearsal system in the phonological loop is believed to be a gradual process that begins developing around the age of 7. The developmental trajectories are similar for boys and girls. Additionally, auditory information and textual information both seemed to be processed in a similar manner, namely without labeling or recoding, leading to single coding. In contrast, pictures are assumed to be processed by the dual coding of both the visual information and a (verbal) labeling of the pictures.     

Linking Mission and Networks

The Ecumenical Water Network (EWN) is a network of churches and Christian organizations promoting people’s access to water around the world. There are many actors on advocacy for water justice; the EWN was formed to make a Christian witness be heard in the present debate on water issues. This article reflects on the meaning of spirituality for the EWN as an organization and on the relationship the EWN has with other actors in the field of water justice. This reflection is intended to ponder the questions which the EWN places at the core of its mission: “why we do, what we do?” Answering these questions contributes to theories and practices on mission and diversity and provides a stimulus to the manner in which organizations for mission and water justice deal with diversity. The perspectives derive from theology, mission studies, management sciences, and social anthropology.     

Studies on wild house mice VI: Differential effects of the Y chromosome on intermale aggression

The aim of this study is to determine the effects of different parts of the Y chromosome of wild house mice on aggression. To reach this goal, intercrosses were made between two selection lines for attack latency (SAL and LAL) and their congenic strains (SAL. LY and LAL. SY). This procedure resulted in F₁ hybrids that carried the same autosomes, but differed in their X chromosome and the two different parts of their Y chromosomes, the different parts of the Y chromosome being a recombining part called the pseudoautosomal region (PAR) and a non-recombining part (non-PAR). We conclude that both parts of the Y chromosome contribute slightly but significantly to variation in aggression. The major effect is accomplished by the PAR of the aggressive parent; a mirror effect is achieved by the non-PAR of the aggressive parent in interaction with the PAR. © 1994 Wiley-Liss, Inc.     

Studies on wild house mice iv: On the heredity of testosterone and readiness to attack

An attempt was made to determine the role of the Y chromosome in the development of aggression in wild house mice. The aggression-eliciting property of testosterone depends not only on circulating adult testosterone, but also on perinatal sensitization of the central nervous system to this steroid. Results of crosses between aggressive (SAL) and non-aggressive (LAL) mice indicate that adult plasma testosterone in these mice is determined by the autosomes, high testosterone levels being dominant over low levels. Conversely, the Y-chromosomal effect seems related to perinatal processes that sensitize the brain for testosterone.     

Contents of Volume 14

Volume Contents

Contents of Volume 14     

Rationale for a pragma-dialectical perspective

Starting from a concept of reasonableness as well-consideredness, it is discussed in what way science could serve as a model for reasonable argumentation. It turns out that in order to be reasonable two requirements have to be fulfilled. The argumentation should comply with rules which are both problem-valid and intersubjectively valid. Geometrical and anthropological perspectives don't meet these criteria, but a critical perspective does. It is explained that a pragma-dialectical approach to argumentation which agrees with this critical perspective is indeed problem-valid and that strong pragmatic and utilitarian arguments can be given for its intersubjective validity. Thus, conventional validity is promoted for a code of conduct for discussants who want to resolve their disputes reasonably by way of a critical discussion.