On Finitely-Valued Inference Systems

A proof-theoretical analysis of finite-valuedness in the domain of cumulative inference systems is presented.     

Gender and leadership emergence: A meta‐analysis and explanatory model

Research has shown that men tend to emerge as leaders more frequently than women. However, societal role expectations for both women and leaders have changed in the decades since the last empirical review of the gender gap in leader emergence (Eagly & Karau, 1991). We leverage meta‐analytic evidence to demonstrate that the gender gap has decreased over time, but a contemporary gap remains. To understand why this gap in leader emergence occurs, we draw on social role theory to develop a Gender‐Agency/Communion‐Participation (GAP) Model—an integrative theoretical model that includes both trait and behavioral mechanisms. Specifically, we examine a sequence of effects: from gender to agentic and communal personality traits, from these traits to behavioral participation in group activities, and ultimately from participation to leader emergence. The model is tested using original meta‐analyses of the personality and behavioral mechanisms (coding 1,632 effect sizes total). Gender differences in leadership emergence are predominately explained by agentic traits (positive) and communal traits (negative), both directly and through the mechanism of participation in group discussions. In addition, several paths in the theoretical model are moderated by situational contingencies. Our study enhances knowledge of the mechanisms and boundary conditions underlying the gender gap in leader emergence.     

Application of regression and neural models to predict competitive swimming performance

This research problem was indirectly but closely connected with the optimization of an athlete-selection process, based on predictions viewed as determinants of future successes. The research project involved a group of 249 competitive swimmers (age 12 yr., SD = 0.5) who trained and competed for four years. Measures involving fitness (e.g., lung capacity), strength (e.g., standing long jump), swimming technique (turn, glide, distance per stroke cycle), anthropometric variables (e.g., hand and foot size), as well as specific swimming measures (speeds in particular distances), were used. The participants (n = 189) trained from May 2008 to May 2009, which involved five days of swimming workouts per week, and three additional 45-min. sessions devoted to measurements necessary for this study. In June 2009, data from two groups of 30 swimmers each (n = 60) were used to identify predictor variables. Models were then constructed from these variables to predict final swimming performance in the 50 meter and 800 meter crawl events. Nonlinear regression models and neural models were built for the dependent variable of sport results (performance at 50m and 800m). In May 2010, the swimmers' actual race times for these events were compared to the predictions created a year prior to the beginning of the experiment. Results for the nonlinear regression models and perceptron networks structured as 8-4-1 and 4-3-1 indicated that the neural models overall more accurately predicted final swimming performance from initial training, strength, fitness, and body measurements. Differences in the sum of absolute error values were 4:11.96 (n = 30 for 800m) and 20.39 (n = 30 for 50m), for models structured as 8-4-1 and 4-3-1, respectively, with the neural models being more accurate. It seems possible that such models can be used to predict future performance, as well as in the process of recruiting athletes for specific styles and distances in swimming.     

‘Numerical trap’. A new look at outcome representation in studies on choice behaviour

In almost all experimental studies on choice behaviour the consequences of choices are limited to denumerable goods (usually money) and represented in a numerical way. It is argued that a different way of representing consequences would cause differences in social orientations. In an exploratory study (1) the kind of consequences (money, satisfaction with money and satisfaction with the situation) and (2) the way of representing consequences (numbers, rectangles, and faces) were varied. No differences were found between the three kinds of consequences represented by rectangles. Representation of money by numbers did not differ from representation of money by rectangles. However, subjects in the condition in which satisfaction with money was represented by faces were more cooperative and altruistic and less equality-oriented than subjects in the corresponding condition in which satisfaction with money was represented by rectangles. Additional correlational analyses showed differences between ways of representing consequences. It was concluded that both for theory and for future research it is important to consider how consequences are represented.     

Sex reversal in female Betta splendens as a function of testosterone manipulation and social influence

In Experiment 1, female Betta given daily injections of testosterone (T) for 9 weeks acquired anatomical features characteristic of males as indicated by changes in fin length, body coloration, and gonadal morphology. These findings suggested that a potential for sex reversal exists in females of this species. In Experiment 2 we measured changes in aggressive behavior during testosterone-induced anatomical changes. Aggression decreased toward females and increased toward males as treatment with T progressed. The final displays of aggressive behavior and anatomical characteristics of fish injected with T resembled those of typical males. In Experiment 3, female Betta primed with T injections for 3 or 6 weeks and permitted to interact socially with females continued to display characteristics of sex reversal after T supplementation ceased. Sex reversal in isolated fish injected with T for 3 or 6 weeks was not sustained, and fish receiving only the control vehicle showed negligible change in both the isolated and community conditions. We discuss the results in terms of similarities with the sex change process found in isolated communities of coral reef fish.     

Problematyka indukcji w pracach i działalności Kazimierza Ajdukiewicza

Allatum est die 10 Aprilis 1964     

Changes of chaoticness in spontaneous EEG/MEG

Depending on the task being investigated in EEG/MEG experiments, the corresponding signal is more or less ordered. The question still open is how can one detect the changes of this order while the tasks performed by the brain vary continuously. By applying a static measurement of the fractal dimension or Lyapunov exponent, different brain states could be characterized. However, transitions between different states may not be detected, especially if the moments of transitions are not strictly defined. Here we show how the dynamical measure based on the largest local Lyapunov exponent can be applied for the detection of the changes of the chaoticity of the brain processes measured in EEG and MEG experiments. In this article, we demonstrate an algorithm for computation of chaoticity that is especially useful for nonstationary signals. Moreover, we introduce the idea that chaoticity is able to detect, locally in time, critical jumps (phase-transition-like phenomena) in the human brain, as well as the information flow through the cortex.     

An essay on resolution logics

This paper discusses the resolution principle in the context of non-classical logics.Research supported by the grant from Natural Sciences and Engineering Research Council of Canada.