Changes in processing of masked stimuli across early- and late-night sleep: a study on behavior and brain potentials

Sleep has proven to support the memory consolidation in many tasks including learning of perceptual skills. Explicit, conscious types of memory have been demonstrated to benefit particularly from slow-wave sleep (SWS), implicit, non-conscious types particularly from rapid eye movement (REM) sleep. By comparing the effects of early-night sleep, rich in SWS, and late-night sleep, rich in REM sleep, we aimed to separate the contribution of these two sleep stages in a metacontrast masking paradigm in which explicit and implicit aspects in perceptual learning could be assessed separately by stimulus identification and priming, respectively. We assumed that early sleep intervening between two sessions of task performance would specifically support stimulus identification, while late sleep would specifically support priming. Apart from overt behavior, event-related EEG potentials (ERPs) were measured to record the cortical mechanisms associated with behavioral changes across sleep. In contrast to our hypothesis, late-night sleep appeared to be more important for changes of behavior, both for stimulus identification, which tended to improve across late-night sleep, and for priming, with the increase of errors induced by masked stimuli correlating with the duration of REM sleep. ERP components proved sensitive to presence of target shapes in the masked stimuli and to their priming effects. Of these components, the N2 component, indicating processing of conflict, became larger across early-night sleep and was related to the duration of S4 sleep, the deepest substage of SWS containing particularly high portions of EEG slow waves. These findings suggest that sleep promotes perceptual learning primarily by its REM sleep portion, but indirectly also by way of improved action monitoring supported by deep slow-wave sleep.     

Coping with challenge and hindrance stressors in teams: Behavioral,cognitive, and affective outcomes

The purpose of this study was to utilize the challenge–hindrance framework to examine the discrete and combined effects of different environmental stressors on behavioral, cognitive, and affective outcomes at the team level. Results from 83 teams working on a command and control simulation indicated that the introduction of a challenge stressor positively affected team performance and transactive memory. The introduction of a hindrance stressor negatively affected team performance and transactive memory and positively affected psychological withdrawal. When the hindrance stressor was combined with the challenge stressor, teams exhibited the lowest levels of performance and transactive memory, and the highest levels of psychological withdrawal. These effects were due to the adoption of specific coping strategies by team members. Implications are discussed, as well as limitations and directions for future research.     

Argumentation in ethics, legal dogmatics and legal practice

The author adopts a coherentist approach to legal argumentation.Ceteris paribus, the degree of coherence of argumentation depends on answers to such questions as: How many statements belonging to the justification are supported by reasons, that is, not arbitrary?, How profound is the justification, that is, how long are the chains of reasons it contains?, How closely interconnected are the reasons, for example in such a way that the same conclusion follows from various independent reasons?, How relevant are the reasons in the context in question?, etc.A reasonable legal argumentation is a special case of a reasonable moral argumentation. Both contain moral substantive reasons and legal authority reasons. On the other hand, some particularities of legal argumentation must be noticed, as well. Among other things, the lawyers take for granted that legal reasoning is based on valid law and that some sources of law, such as statutes, are binding.There exist various juristic roles and corresponding types of argumentation, e.g., judicial and doctrinal ones. Yet, all kinds of legal argumentation must use weighing and balancing in order to make the law coherent and morally acceptable. Consequently, all general principles and criteria of coherence are applicable to all these types but their weight varies between them.     

VEP latency and some properties of simple motor reaction-time distribution

Summary The median of simple motor reaction (RT) to a flash parallels the latencies of visually evoked potential (VEP) deflections if flash intensity is varied. However, mean and median reaction times are not equal because of the skewness of RT distribution. It therefore seemed plausible that the mean reaction time — intensity relationship would be steeper than that for VEP latency. Such divergence would account for the intensity-dependent motor component of RT revealed by other psychophysical studies. The latencies of VEP deflections were measured as a function of intensity and the results were compared with mean and median RTs. The difference between mean and median RT is constant and independent of flash intensity. Moreover, both values are parallel to VEP latency. The general pattern of results remains the same after a change in the distribution from which the foreperiod is sampled.     

Three contributions to the two-valued propositional calculus

Summary Three chapters contain the results independent of each other. In the first chapter I present a set of axioms for the propositional calculus which are shorter than the ones known so far, in the second one I give a method of defining all ternary connectives, in the third one, I prove that the probability of propositional functions is preserved under reversible substitutions. This paper appeard orginally under the title “Trois contributions an calcul des propositions bivalent” inStudia Societatis Scientiarum Torunensis, Toruń, Polonia, Sectio A, vol. I (1948), pp. 3–15.     

Accuracy and performance of the state-based Φ and liveliness measures of information integration

A number of people have suggested that there is a link between information integration and consciousness, and a number of algorithms for calculating information integration have been put forward. The most recent of these is Balduzzi and Tononi’s state-based Φ algorithm, which has factorial dependencies that severely limit the number of neurons that can be analyzed. To address this issue an alternative state-based measure known as liveliness has been developed, which uses the causal relationships between neurons to identify the areas of maximum information integration. This paper outlines the state-based Φ and liveliness algorithms and sets out a number of test networks that were used to compare their accuracy and performance. The results show that liveliness is a reasonable approximation to state-based Φ for some network topologies, and it has a much more scalable performance than state-based Φ.