Controlling the Ground Reaction Force During Lifting

The control of the ground reaction force vector relative to the center of gravity (CoG) was examined while subjects performed a back-lifting task. Six male subjects (aged 24.0 +/- 2.5 years) repeatedly lifted a barbell. A biomechanical analysis that used a linked segment model revealed that the summed rotations of body segments during lifting yielded a specific rate of change of the angular momentum of the entire body. This equaled the external moment provided by Fsubg; relative to CoG. This implies that multisegment movements involve control of the angular momentum of the entire body through an appropriately directed Fsubg;. Thus, in dynamic tasks Fsubg; is pointed away from rather than lined up with the CoG, as is the case in static tasks.     

Analysing and evaluating problem-solving discussions

In this article, the conceptual instrument that pragma-dialectical argumentation theory offers is elaborated for the analysis and evaluation of problem-solving discussions. The elaboration is aimed expressly at taking into account the discussion character of the discourse, in order to show how the developing process evolves and what the obstacles are therein. In addition, it focuses expressly on the verbal behaviour of the participants and on showing how this behaviour controls the evolving process. The analysis and evaluation is based on insights and methods of conversational analysis and discourse analysis. One fragment of a problem-solving discussion is analysed and evaluated.     

Children's capacity to agree to psychological research: knowledge of risks and benefits and voluntariness

A series of studies investigated the capacity of children between the ages of 7 and 12 to give free and informed consent to participation in psychological research. Children were reasonably accurate in describing the purpose of studies, but many did not understand the possible benefits or especially the possible risks of participating. In several studies children's consent was not affected by the knowledge that their parents had given their permission or by the parents saying that they would not be upset if the children refused. In contrast, other studies found that children were much more likely to stop their participation if the experimenter said explicitly that she would not be upset if they stopped. We suggest that experimenters should pay more attention to describing the possible risks and benefits of participation in research, and that they should also make it clearer to children that they are free to stop once they have begun.     

Propositional attitudes and formal ontology

This paper develops — within an axiomatic theory of properties, relations, and propositions which accords them well-defined existence and identity conditions — a sententialist-functionalist account of belief as a symbolically mediated relation to a special kind of propositional entity, theproxy-encoding abstract proposition. It is then shown how, in terms of this account, the truth conditions of English belief reports may be captured in a formally precise and empirically adequate way that accords genuinely semantic status to familiar opacity data.I am deeply indebted to Edward Zalta for many helpful comments and suggestions.     

The dynamics of Prägnanz

Summary There is quite wide-spread agreement about the relevance of pattern Pragnanz (Koffka, 1935) with respect to the human interpretation of visual patterns. There is less agreement about whether pattern Pragnanz is based solely on pattern information (static) or also on the history of the perceiver (dynamic). In Van Leeuwen and Van den Hof (1991), experimental data concerning serial patterns are presented within the framework of the dynamic-network approach initiated by Buffart (1986, 1987). These experimental data are claimed to give evidence against the static-coding approach initiated by Leeuwenberg (1969, 1971). In the present paper, however, I show first that Buffart's theoretical basis is incorrect, and that in fact Leeuwenberg's static-coding approach is the basis for the dynamic-network approach. Second, I show that those experimental data rather give evidence in favor of the static-coding approach, by using those same data for a test of the most recent static-coding model (Van der Helm & Leeuwenberg, 1991; Van der Helm, Van Lier, & Leeuwenberg, 1992). Finally, I propose a reconciliation between the two approaches, in the sense that the dynamic-network model could be shaped in such a way that it yields a simulation, and maybe even an enrichment, of the static-coding model.     

Conditional Control of Fluid Consumption in an Occasion Setting Paradigm Is Independent of Pavlovian Associations

Drug states, flavors, and contextual cues were each trained as conditional discriminative stimuli to control a saccharin-LiCl association. In transfer tests, drug states transferred control over consumption to other flavored solutions and to food. Contexts and flavors transferred control only to other flavored solutions. Pavlovian control groups given direct pairings of context-LiCl or flavor-LiCl did not show reliable transfer. However, these control groups did show greater or the same aversion to the specific context or flavor predicting LiCl compared to the context or flavor discrimination groups. The dissociation of the discrimination and Pavlovian groups on transfer versus preference tests suggests that performance on the occasion setting task cannot be due to simple excitation or learning about a unique compound cue. Data from extinction procedures provide further support for the dissociation between simple excitation and occasion setting.     

Are beliefs brain-states? And if they are what might that explain?

Philosophical Studies -     

Communication in preterm infants: Why is it different?

The present paper selectively reviews the literature which compares full-term and preterm infants' communication with their mothers in the first year of life. The review is focused not only on what differences are found between full-term and preterm infants, but also why such differences exist. Particular emphasis is placed on the importance of interpreting the findings in the light of the developmental phase of the infants, the heterogeneity of the preterm population and the situation in which communication is studied. Most studies were not designed to consider these issues in any detail. Differences with respect to these factors can be found between studies, however, which may have contributed to the often contradictory findings. Consequently, comparisons between these studies provide clues about the effects of these factors on communicative development. The ultimate goal of this review is to point to important directions for future research on early communication in preterm infants.