National Repository of Grey Literature 55 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Simulation of processes predicted by theory of frozen plasticity
Nekola, Ondřej ; Flegr, Jaroslav (advisor) ; Ponížil, Petr (referee)
The question of the tempo of evolution is amongst the oldest conundrums in evolutionary biology and has not been satisfactorily answered yet. One of the attempts to do so is the frozen plasticity theory, which postulates that a sexually reproducing species is only capable of evolution within short periods of time after its genetic polymorphism decreases e.g. as a consequence of peripatric speciation. In the longer periods of evolutionary stasis, its evolution is limited by frequency- dependent selection and pleiotropy. In this work, I have produced an open source software simulating the respon- ses of populations of sexually reproducing individuals to varying environmental conditions. Using this software, I simulated evolution of populations with different probabilities of arising of alelles affecting more phenotypic traits and frequency- dependent selected alleles that have opposing phenotypic effects when present at the locus in one copy, respectively two copies. I observed trends predicted by the theory of frozen plasticity: slower adap- tation to instant environmental changes, lower achieved fitness and more frequent extinctions of populations with higher portions of investigated types of alleles, but only with low effect sizes and without statistical significance. For future research, it would be desirable...
Biological and social predictors and correlates of human morality
Kopecký, Robin ; Flegr, Jaroslav (advisor) ; Špinka, Marek (referee) ; Houdek, Petr (referee)
In this dissertation, we delve into the multifaceted domains of biological and social factors influencing human morality. The connecting element of this collection of four studies is both an interest in human morality as a traditional philosophical topic and the use of methods from empirical sciences, particularly biology, behavioural, and cognitive sciences. The first study focuses on the moral algorithms in autonomous vehicles. We examined moral preferences regarding the choice between software types that differ in their built-in algorithms for dealing with lethal collisions. These are categorized into three specific types: selfish, altruistic, and conservative. Respondents exhibited a preference for the altruistic strategy, which is reinforced when signalled to others. The altruistic preference is the most pronounced when it applies to everybody else, weaker when it reflects only a personal choice, and the weakest when choosing for one's own child. We conclude that making a choice public significantly sways individuals towards a more socially beneficial solution. The second study investigates the relationship between parasite Toxoplasma gondii infection and its subsequent impact on human political beliefs and values. Infected participants exhibited a tendency towards heightened tribalism and...
Current methods of measuring cognitive abilities
Bílková, Kateřina ; Flegr, Jaroslav (advisor) ; Binter, Jakub (referee)
The aim of this thesis is to present a selection of cognitive ability measurement methods for adults, especially those that can be administered online. These methods are presented in the context of cognitive ability composition concepts on which they are based. The chosen methods include several IQ tests and various online cognitive performance measurement methods. IQ tests represent measures of general intelligence. The IQ tests mentioned in this study are administered individually or in group settings. The online methods have a narrower focus and are mentioned in conjunction with the platforms that offer these methods. The selection of online methods was based on their prevalence in the literature, with an emphasis on the more common ones, in order to collectively cover a broader range of cognitive abilities. The reliability and validity of the methods are discussed.
Human Perception in Condition of Uncertainty: The Visual, Auditory and Embodied Responses to Ambiguous Stimuli
Boschetti, Silvia ; Flegr, Jaroslav (advisor) ; Palanza, Paola (referee) ; Pfaus, James (referee)
In order to orient ourselves in the environment our senses have evolved so as to acquire optimal information. The optimization, however, incurs mistakes. To avoid costly ones, the over-perception of patterns (in humans) augments the decision making. I tested the decision- making in two modalities, acoustic and visual. A set of stimuli (using computer-generated graphics, based on output from a very good pseudo random generator) was produced: masks with a random pattern with varying degree of transparency over geometrical figures were used, followed by similar task that involved black and white high-contrast patterns. In both cases, I was able to find, using a Bayesian statistical approach, that the ability to detect the correct pattern presence (or lack thereof) was related to respondents' thinking styles, specifically Rationality and Intuition. Furthermore, I used ambiguous facial expressions, and accompanying vocalizations, of high-intensity affects (pain, pleasure and fear) and low- intensity (neutral and smile/laughter). My findings evidenced that the high-intensity facial expressions and vocalizations were rated with a low probability of correct response. Differences in the consistency of the ratings were detected and also the range of probabilities of being due to chance (guessing). When...
The effect of latent toxoplasmosis on memory performance in infected persons
Hejduk, Tomáš ; Flegr, Jaroslav (advisor) ; Levčík, David (referee)
The relationship between latent toxoplasmosis and the memory processes has not been studied in detail. There is an assumption of a possible link between latent toxoplasmosis and memory, due to the generally weaker cognitive performance and worse prognosis of Toxoplasma-positive patients with schizophrenia. The aim of this study was to verify whether the latent toxoplasmosis along with Rh phenotype affects the memory of Toxoplasma-infected individuals. Visual-spatial working memory was tested by the Spatial Span test, Meili test and Virtual Four Goals Navigation task. These tests were performed on a group of 307 students of the Faculty of Science, Charles University. The results of these tests demonstrated the negative impact of latent toxoplasmosis on visual-spatial working memory. It was detected that Toxoplasma-positive men remember more subjects with aggressive themes, while Toxoplasma-positive women remember less subjects with aggressive themes. The findings could be related to the previously observed changes in the concentration of testosterone in infected men and women. The protective effect of Rh positivity was not confirmed, as in many sub-tests the worse memory performance was by Rh positive individuals with latent toxoplasmosis. Keywords: Latent toxoplasmosis, Rh factor, visual-spatial...
Methods of measurement of intelligence in adult subjects
Chvátalová, Veronika ; Flegr, Jaroslav (advisor) ; Lindová, Jitka (referee)
In my work I focus on intelligence testing in adult subjects. The work aims to introduce to the readers six intelligence tests that might be administered both individually and in a group. Besides intelligence tests measuring complex intelligence abilities I would like to mention also a partial test measuring nonverbal abilities. Characteristics, structure and description of tasks will be specified for each test as well as psychometric properties and usage. Advantages and disadvantages of each test will be evaluated in the end. Where possible, I present also the usage of each test in the Czech Republic or in Europe.
The role of ecological factors in maintenance of sexuality
Toman, Jan ; Flegr, Jaroslav (advisor) ; Janko, Karel (referee)
The existence and widespread distribution of sexual reproduction despite its obvious disadvantages is an evolutionary enigma. According to the theory of frozen plasticity, the evolution of sexual and asexual species is fundamentally different. One of the implications of this theory are different ecological preferences of these species. Sexual species should prefer biotically and abiotically variable environments because of their ability to quickly and reversibly respond to unpredictable changes. On the other hand, asexual species should prosper in biotically and abiotically stable environments because of their ability to perfectly adapt even to extreme environmental factors in the long term. I decided to test these predictions in the metastudy comparing ancient asexual clades (in which we can be sure about their obligate asexuality and evolutionary longevity) with their sexual sister or closely related ecologically comparable clades. The hypothesis of the preference of asexual species to biotically and abiotically homogenous environments was supported by the results of this metastudy. On the other hand, the hypothesis of supposed ability of asexual species to perfectly adapt to a broader range of environmental conditions, tested on the comparison of temperature ranges of activity of previously...
Ecological aspects of sexual reproduction
Toman, Jan ; Flegr, Jaroslav (advisor) ; Markoš, Anton (referee)
Sexual reproduction is one of the most interesting biological phenomena. No theory has ever entirely explained its wide occurrence among Eukaryotic clades despite its clear disadvantages (e.g. twofold price of sex). Theories can be divided into three groups according to the approach to solve this problem - molecular, genetic and ecological (environmental). Environmental theories are slightly preferred in the last decades and the opinion that the key to the sex enigma lies among them is widely accepted. Most of the environmental theories do not counter each other and there is possibility either to integrate them in several ways or presume that several of these theories might act simultaneously. According to theories, abiotically stable environments without biotic interactions (homogenous) should be suitable for and select for asexual species, whereas environments abiotically variable and rich in biotic interactions (heterogenous) should be suitable for and select for sexual species. The anagenetic phenomenon of punctuated equilibria and some of its explanations, e.g. P. R. Sheldon's Plus ça change hypothesis or J. Flegr's Frozen plasticity theory, also supports this division. There is a vast amount of empirical data supporting this division in ecological studies. Clearly homogenous environments...
Influence of latent toxoplasmosis on intelligence of infected subjects
Chvátalová, Veronika ; Flegr, Jaroslav (advisor) ; Lindová, Jitka (referee)
There remain inconsistencies in the literature concerning the intelligence of subjects infected with latent toxoplasmosis. The main goals of this work are to find out whether, a) latent toxoplasmosis influences the intelligence of infected subjects and b) whether Rh negative and Rh positive subjects respond to the infection in different ways. In this work we used a complex test of intelligence, The Structure Intelligence Test I-S-T 2000 R. We were able to statistically control for the confounding variable the size of the place of residence in childhood. This had benefits when compared to previous studies. The differences in intelligence were measured in students of The Faculty of Science. The sample used included 46 toxoplasma-infected and 188 toxoplasma-free individuals. Using nonparametric tests we found lower numerical, fluid and general intelligence in toxoplasma-infected subjects compared to noninfected subjects. In addition, these tendencies were also observed in the results of parametric tests. Further to these components of intelligence there was also found to be a lower component of numerical knowledge in toxoplasma-infected males. By contrast, no differences between infected and noninfected individuals was found to occur in the female test subjects. No statistically significant...

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3 FLEGR, Jan
3 Flegr, Jan
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