In recent years, there has been a growing commitment to studying the economic lives of the poor by better understanding their psychological lives (Banerjee and Duflo, 2007; Schilbach et al., 2016). These developments stem from the failure to empirically detect poverty traps, which have been at the core of the development literature for decades (Dean et al., 2017). Instead, empirical studies document the existence of very large rates of returns to investment, which, however, are not matched by observed consumption growth rates (Kremer et al., 2019). Several behaviors of the poor, which do not fit with traditional models, puzzled economists. Why do poor micro-entrepreneurs keep borrowing at extremely high interest rates instead of saving some of their profit to borrow less with each passing day (Ananth et al., 2007)? If using fertilizer has such high rates of return, why don't poor farmers purchase it (Duflo et al., 2008)? If the poor remain poor because they do not get enough calories, why do they spend their money on other things besides food (Banerjee and Duflo, 2007)? Such questions led to the rise of the subfield of Behavioral Development Economics, which applies insights from psychology and behavioral economics to study the economic behavior of the poor; trying to explain why and how it departs from standard economic models. Behavioral biases, studied extensively in Behavioral Economics, may be much more consequential for the poor. Failing to resist to the temptation of a hedonistic reward after a hard day of work will have very different implications for a poor person than for a rich one. This thesis aims to contribute to this new strand of literature, in particular to one of its branches titled "the psychology of poverty", which studies the impact poverty has on cognitive function and economic behavior. One influential theory in this field is the scarcity/mental bandwidth theory (Mullainathan and Shafir, 2013), which states that poverty implies not only lack of financial resources, but also lack of mental resources to focus on other things besides pressing concerns. At any time, a poor person's mind will be preoccupied with worries about bills, school fees or health problems; and how to best manage all of them with very limited resources. While this makes the poor better at decisions regarding the pressing issue at hand (Mullainathan and Shafir, 2013), it also makes them neglect other important domains which may not appear urgent enough (Shah et al., 2012, 2015). While the theory may help explain many puzzling behaviors of the poor, up to now there has been little evidence on real-world economic outcomes. The first two chapters of this thesis try to bring the framework closer to real-world economic decisions even though restricted to the lab setting. The main challenge with studying the psychology of poverty outside the lab is the fact that even exogenous changes in income will affect several other channels besides mental bandwidth, making it very challenging to pin down the precise mechanism. Given this, the first two chapters are limited to varying mental bandwidth in a lab setting, keeping income fixed. The novel aspect is that the decisions participants make mimic closely everyday life purchasing decisions, involving real products. I note however, that due to limited funding and ethical considerations, in both chapters decisions are only weakly incentivized: only 1% of participants actually receive the goods they selected. The first chapter explores the relationship between the psychology of poverty, investment in human capital, and financial incentives. Empirical evidence indicates that the poor are less attentive parents, investing less in the human capital of their children (McLoyd, 1998; Evans, 2004). This contributes to the inter-generational transmission of poverty because investing in human capital has extremely high rates of return, highest in early childhood (Cunha and Heckman, 2007; Cunha et al., 2010). The question is why don't the poor invest more? Traditional answers to this question put the blame on lack of knowledge of parenting practices, wrong beliefs on the expected returns or lower altruism. We propose an alternative explanation based on the scarcity theory. Poor parents may fail to invest the required time and resources in their child because their minds are preoccupied with other more urgent concerns. When there is uncertainty about how the next bill will be paid, spending time doing educational activities with the child may shift out of focus. When such behaviors keep repeating on a regular basis, a gap emerges between poor and non-poor children in the amount of cognitive and emotional stimulation they receive. The challenge is how to test this hypothesis. Given the identification issues with disentangling such channels with observational data, we bring it to the lab. Parents of toddlers, living in the UK, are invited to participate in an online experiment. First, they are asked to answer how their family would deal with various hypothetical financial scenarios which vary in severity (hard for the treatment group, easy for the control group). Among the treated, the scenarios aim to bring financial worries to mind, trying to capture what people living in poverty experience on a regular basis. After completing the scenarios, parents receive a budget of pounds 30 to be spent as they choose in an experimental market on 3 types of goods: necessities, child investment goods, and luxury goods. Half of parents are incentivized to purchase more child investment goods by being offered a 50% discount. This treatment investigates if financial worries change how parents respond to such incentives, and is motivated by the results in Das et al. (2013) which find that accounting for household re-optimization in response to a policy is crucial when evaluating its effects. We find that the incentive increases investment in human capital among lower income parents only when financial worries are not salient. When worries become salient, low income parents do not invest more but instead use the additional money to increase their demand of necessities. In addition, they also lower their demand for luxury goods to zero. When no discount is offered, we do not find financial worries to lower investment, which is likely to be explained by floor effects. Among higher income parents, financial worries do not affect behavior. The effects among lower income participants are driven by those who were further away from their last paycheck at the time of the experiment - an indicator of real world monetary scarcity. This finding increases the external validity of our main results. The second chapter departs from studying the human capital of children, focusing instead on the human capital of adultsootnote{However, the behavior studied is likely to have negative externalities also on children (e.g. domestic violence).}. Addictive (or temptation) goods have been at the core of academic and policy debates for decades. With Becker and Murphy (1988), addiction was rationalized as a utility maximizing decision where the individual fully internalizes the costs of consuming such goods. In this framework, the only scope for intervention is to balance out the externalities -- the costs that individuals place on society through consumption decisions (e.g. healthcare costs). Gruber (2001) questioned theoretically and empirically the rational framework, showing that with inconsistent time preferences, individuals do not fully internalize the cost of their behavior. Further studies have confirmed these findings which increased the scope of policy interventions (Gruber and Kőszegi, 2004; O’Donoghue and Rabin, 2006; Allcott et al., 2019a). The most widely used policy tools to limit the over-consumption of temptation are "sin" taxes, popular among governments because they bring large revenues. However, such taxes have sparked debates regarding their effects on income distribution. Since the poor tend to spend a higher share of their budget on temptation, they are likely to pay a higher cost. On the other hand, they are also the ones expected to benefit more in terms of health by consuming less. Traditionally, such taxes were placed on tobacco and alcohol. Recently, several governments have started adding taxes also on the consumption of unhealthy foods, such as sugary drinks and beverages. Crucial to determining the effect of the tax is the elasticity of demand with respect to price and the degree to which individuals are not internalizing their choices (Allcott et al., 2019a). The second chapter integrates the economics of temptation with the scarcity theory, and investigates if financial worries affect (i) the demand for temptation and (ii) the elasticities of demand with respect to price (sin taxes). The first question is not straightforward in the scarcity framework. While poverty is scarcity of financial resources, it is also scarcity of immediate gratification. The poor have stressful lives and jobs which are often less rewarding and highly physically demanding. Compensating for these struggles is harder since they can only access a small set of potential alternatives to addictive goods (e.g. going to nice restaurant and travelling are not really in the choice set of the poor). Following a similar design as in the first chapter but with a less specific population (adults living in the UK), we randomly trigger financial worries before asking participants to choose between necessities and temptation goods in an experimental market. The basket of temptation goods offered includes tobacco, alcohol and unhealthy foods and we simulate "sin taxes" by randomly increasing the price of temptation by 10% or 20%. We find that triggering financial worries lowers the demand for temptation but also dampens demand elasticities. The effects are stronger among low income participants. When financial worries are salient, their demand curve is actually slightly upward sloping. The finding is puzzling: financial worries appear to limit over-consumption of temptation, but they also hurt the poor the most when additional taxes are introduced. We find suggestive evidence that both effects are mediated by an increased focus on urgent necessities. The first two chapters integrated the scarcity framework into public policies. The results are very consistent across studies and have clear policy implications. Among the poor, when monetary concerns are top of mind: (i) incentivizing investments in human capital may not achieve its desired outcome, (ii) (dis)incentivizing consumption of temptation through new taxes may harm the poor the most since they do not lower their demands in response to price increases, which leads, through taxation, to a transfer of funds from the poor to the nonpoor without having any corrective effects (see Bernheim and Rangel, 2004; Bernheim and Taubinsky, 2018). However, I must note that both chapters make only speculative policy recommendations given that they lack the normative counterfactual. Further research is needed to rigorously establish the welfare implications of financial worries. The third chapter takes a step back from economic decisions to studying how violence exposure affects cognitive function in children. Unfortunately violence and poverty are closely linked in a vicious cycle. Economically deprived neighborhoods are in general also more violent. In addition to monetary concerns, the minds of the poor are likely to be preoccupied with safety concerns. This study attempts to apply the framework in Mullainathan and Shafir (2013), focusing on security concerns instead of monetary ones. While the link between the scarcity framework and violence as scarcity of security is novel and up for debate, the chapter is closely connected with the literature on the impact of emotions on cognition and decision making (Loewenstein and Lerner, 2003; Lerner et al., 2003, 2015; Callen et al., 2014; Bogliacino et al., 2017). In a lab-in-the-field experiment, primary school children in El Salvador are randomly assigned to recall episodes of violence exposure before or after taking cognitive tests. I find that recalling violence exposure before taking the tests, increases cognitive performance by 0.2 standard deviations, effect significantly stronger for children reporting higher exposure. The estimates contrast previous findings on the effect of violence and cognitive function (Sharkey, 2010; Sharkey et al., 2012; Bogliacino et al., 2017) and call for further research in the field.

Aim: The purpose of this study was to investigate acute effects of physical exercise of different intensities on working memory. Method: Twelve young adults, 20-40 years, 8 males and 4 females passed the screening and participated in a randomized experimental crossover within-subject design study with three experimental conditions. Working memory was measured with n-back consisting of three difficulty levels.  Results: No significant interaction effect within subjects between the three different exercise intensity conditions for accuracy or response time was found. A significant main effect of time was detected for n-back response time, F(1,11)=40.2, p=<.001, reflecting an overall shorter response time after exercise compared to before, independent of exercise intensity condition. A two-way interaction effect on accuracy was found between n-back session 1 and 2 in the low fitness group.  Conclusions: The exercise intensity does not seem to matter for the improvement of working memory performance. However, participants response time was shown to be faster following any given exercise intensity.

It is imperative to prepare South African learners to participate and function confidently within the context of a rapidly changing world. The curriculum of the South African Education System emphasises the significance of optimising learners‟ cognitive development as early as pre-school age to enable them to become creative and critical citizens who lead purposeful lives in a safe and prejudice-free environment. Despite continuous efforts by educators to optimise cognitive development, recently executed research studies indicate that cognitive development has not been adequately optimised in South African schools. This study was undertaken to establish the cognitive development level (cognitive and meta-cognitive skills and strategies, cognitive functions and non-intellective factors) of Grade R-learners and to determine the effect of an intervention programme, the Cognitive Enhancement Programme for Pre-schoolers (CEPP), on their cognitive development. By means of a literature study, I investigated whether, to what extent the cognitive development of Grade R-learners was taking place, and established which cognitive and meta-cognitive thinking skills and strategies, cognitive functions and non-intellective factors are required for effective cognitive development among Grade R-learners. In addition to this, the role of mediation for optimising cognitive development was investigated. A concurrent embedded mixed methods design was conducted in the implementation of the research. Intervention research within a quasi-experimental research design was applied. The data collection by means of a quantitative strategy (quasi-experimental research) and qualitative strategy (observation study) was executed simultaneously. By means of convenient sampling, one Grade R-class with twenty learners was subjected to a pre-test to establish their cognitive developmental level. The test results as well as the observations conducted during the pre-test revealed that the learners experienced problems related to their cognitive development. Ten of the twenty learners were then divided purposively based on their test performance into two experimental groups, Experimental Group A and Experimental Group B consisting of five participants each. Experimental group A and Experimental Group B took part in the CEPP intervention based on the principles of mediation on a rotational basis over a period of twelve weeks, during which intentional attempts were made to optimise their cognitive development. Both groups completed a post-test and delayed post-test (retention) to determine the effect of the CEPP intervention on their cognitive development. In addition to the test results, observations in the form of structured running and anecdotal records and reflective notes were utilised to understand the nature and quality of the cognitive development of the learners better. Furthermore, the effect of the intervention on their cognitive development was established. The cognitive development of Grade R-learners who participated in this study was optimised, which is a clear indication that cognitive capacity can be optimised when instruction is based on the principles of mediation / PhD, Teaching and Learning, North-West University, Vaal Triangle Campus, 2012

<p>Iskustvo u radu sa studentima pokazalo je da studenti nedovoljno ĉesto ostvaruju zadovoljavajuće ishode uĉenja na lingvistiĉkim predmetima na studijama engleskog jezika, &scaron;to je takoĊe opisano i u stranoj literaturi. Kao jedan od razloga navodi se nastava koja upućuje studente na pasivnost, te oni pribegavaju memorisanju i reprodukciji materijala kao najĉe&scaron;ćim ishodima uĉenja. Biggs (1999) razraĊuje koncepte dubinskog i povr&scaron;inskog pristupa uĉenju, koje relevantna literatura smatra kljuĉnim faktorima za kvalitet ishoda uĉenja. Dubinski pristup uĉenju korelira sa kvalitetnim ishodima uĉenja i funkcionalnim znanjem, a karakteri&scaron;u ga motivacija, zadovoljstvo usled uĉenja, studentska aktivnost i to aktivnost visokih kognitivnih funkcija. Visoke kognitivne funkcije (Bloom i dr. 1956, Anderson i dr. 2001) i povezane kognitivne radnje (re&scaron;avanje problema, analitiĉko, kritiĉko i kreativno razmi&scaron;ljanje) jesu najvaţniji ciljevi visokog obrazovanja jer samo one, usled primene transfera uĉenja, govore o steĉenom i primenljivom, tj. funkcionalnom znanju. Obuka i razvoj visokih kognitivnih funkcija omogući će studentima da uĉenju pristupe dubinski &scaron;to je jo&scaron; jedan razlog da budu osnovni nastavni cilj svih predmeta na ustanovama tercijarnog obrazovanja. U skladu sa ovim teorijskim postavkama postavljene su osnovna i pomoćna hipoteza: upotreba posebno konstruisanih veţbi za aktivaciju vi&scaron;ih kognitivnih funkcija u nastavi lingvistiĉkih predmeta dove&scaron;će do sticanja funkcionalnog znanja na teorijskom i praktiĉnom nivou; steĉeno znanje kroz ovakvu eksperimentalnu nastavu i upotreba tog znanja odraţavaće kognitivne funkcije ne samo niţeg nego i vi&scaron;eg reda: primeniti, analizirati, proceniti, stvoriti, kao i kritiĉko i kreativno razmi&scaron;ljanje i re&scaron;avanje problema. Kako bi se proverile hipoteze, sproveden je eksperiment sa studentima prve godine engleskog jezika (N=34) na Fakultetu za pravne i poslovne studije dr Lazar Vrkatić u Novom Sadu. U istraţivanju sa paralelnim grupama, eksperimentalna grupa je imala veţbe sa aktivnostima koje razvijaju vi&scaron;e kognitivne funkcije na predmetu uvod u op&scaron;tu lingvistiku tokom zimskog semestra &scaron;kolske 2012/2013. godine. UporeĊeni su kvantitativni rezultati kolokvijuma eksperimentalne i kontrolne grupe na kraju semestra, a potom je sproveden intervju sa po pet studenata iz svake grupe radi utvrĊivanja kvalitativnih razlika u kognitivnim procesima kod ove dve grupe. Obe grupe su ostvarile podjednak uspeh na kolokvijumu, te je osnovna hipoteza odbaĉena. Kodirani podaci iz intervjua pokazali su da obe grupe podjednako koriste kognitivne funkcije po broju i distribuciji, te je i pomoćna hipoteza odbaĉena. Kao obja&scaron;njenje za odsustvo većeg uspeha EG navedena su metodolo&scaron;ka ograniĉenja istraţivanja: duţina eksperimentalne nastave, problem dokazivosti transfera i problem kodiranja intervjua. Drugi faktori koji mogu objasniti neuspeh su: prethodno steĉene navike u uĉenju, neshvatanje svrhe izuĉavanja predmeta i dr. UporeĊeni su rezultati boljih i slabijih studenata, te je utvrĊeno da bolji studenti pokazuju veći stepen samostalnosti, da upotrebljavaju vi&scaron;e kognitivne funkcije kao i duţe nizove kognitivnih radnji. Posmatrajući kvalitativne podatke, bolji studenti eksperimentalne grupe pokazali su promenu gledanja na svet usled izuĉavanja lingvistike i izrazili su zadovoljstvo zbog uĉenja ovog predmeta. Oni pokazuju i upotrebu najduţih nizova vezanih kognitivnih radnji. Iz ovoga se moţe zakljuĉiti da su oni pristupili uĉenju dubinski i zbog toga ostvarili kvalitetnije ishode uĉenja. U cilju dono&scaron;enja ĉvrstih zakljuĉaka neophodno je sprovesti dugotrajniji i obuhvatniji multidiciplinarni istraţivaĉki projekat, s obzirom da bi pozitivni rezultati bili od velikog znaĉaja za pobolj&scaron;anje ishoda uĉenja na tercijarnom nivou obrazovanja. Ključne reči: uĉenje i nastava na tercijarnom nivou, taksonomija obrazovnih ciljeva, pristupi uĉenju, vi&scaron;e kognitivne funkcije, transfer uĉenja, funckionalno znanje.</p> / <p>The experience of working with university students has shown that the learning outcomes of linguistic courses are infrequently satisfactory, which is also described in literature worldwide. Teaching philosophy in which students are forced into passives roles is one of the causes since such teaching results in low motivation with memorizing and reproduction of learned materials as the most frequent outcomes of learning. Biggs (1999) develops the concepts of deep and superficial learning approaches which have been declared in the relevant literature as key factors for the quality of learning outcomes. Deep approach to learning correlates with high quality learning outcomes, and is characterized by high motivation, satisfaction with learning and student activity of appropriately high cognitive levels. Higher cognitive functions (Bloom et. al. 1956, Anderson at al. 2001) and related cognitive activities (problem solving, analytical, critical and creative thinking) are the most important goals of higher education since these thinking skills are transferable and therefore represent applicable and functional knowledge. The training and development of the higher cognitive skills enables students to use deep approaches to learning, which is an additional reason to consider them as fundamental teaching goals in all courses in tertiary education. Based on this theoretical framework the main hypothesis and sub-hypothesis were formulated as follows: the use of specially designed practices which activate higher cognitive functions (HCF) will result in acquiring functional knowledge at both theoretical and practical levels; the knowledge gained through such teaching will reflect the use of higher cognitive functions: apply, analyze, evaluate, create, as well as show problem solving skills and critical and creative thinking. To test the hypotheses an experiment was conducted with the first year English language students (N=34) at the Faculty of Legal and Business Studies dr Lazar Vrkatić in Novi Sad. In the parallel groups design, the experimental group (EG) was involved with activities which develop HCFs in the course of Introduction to General Linguistics during the winter semester of the 2012/2013. Quantitative data were collected at the end of the semester (the final test) and compared between the two groups to determine whether the EG scored better results than the control group (CG). This was followed by interviews with five respondents from each group to qualitatively compare the cognitive processes. No statistically significant difference between test results in the two groups was found and so the main hypothesis was rejected. The coded data from the interviews showed an equal number of identified CFs with both groups with similar distribution patterns, thus the sub-hypothesis was also rejected. The absence of better scores of the EG can be explained by some methodological limitations of the experiment, such as the length of the experimental activities, the problem of proof of transfer and the coding of the interview data. Other factors include the existing learning habits of students, the inability to grasp the purpose of studying linguistics, etc. The results of better students were compared to those of the weaker ones, which showed that better students are more autonomous, use a greater number of HCFs and string more CFs into a complex response. Qualitative data also showed that better students of the experimental group expressed a change in how they see the world around them and express satisfaction because of studying linguistics. They also string the longest chains of cognitive activities. These findings lead to a conclusion that better students of the EG used deep approaches to learning which resulted in higher quality learning outcomes. In order to achieve conclusive results, a comprehensive long-term multidisciplinary research project should be carried out, since its results would have a significant impact on the quality of learning outcomes in tertiary education.</p>

L’objectif de la présente étude visait à évaluer les effets différentiels de la privation de sommeil (PS) sur le fonctionnement cognitif sous-tendu par les substrats cérébraux distincts, impliqués dans le réseau fronto-pariétal attentionnel, lors de l’administration d’une tâche simple et de courte durée. Les potentiels évoqués cognitifs, avec sites d’enregistrement multiples, ont été prévilégiés afin d’apprécier les effets de la PS sur l’activité cognitive rapide et ses corrélats topographiques. Le matin suivant une PS totale d’une durée de 24 heures et suivant une nuit de sommeil normale, vingt participants ont exécuté une tâche oddball visuelle à 3 stimuli. L’amplitude et la latence ont été analysées pour la P200 et la N200 à titre d’indices frontaux, tandis que la P300 a été analysée, à titre de composante à contribution à la fois frontale et pariétale. Suite à la PS, une augmentation non spécifique de l’amplitude de la P200 frontale à l’hémisphère gauche, ainsi qu’une perte de latéralisation spécifique à la présentation des stimuli cibles, ont été observées. À l’opposé, l’amplitude de la P300 était réduite de façon prédominante dans la région pariétale pour les stimuli cibles. Enfin, un délai de latence non spécifique pour la N200 et la P300, ainsi qu’une atteinte de la performance (temps de réaction ralentis et nombre d’erreurs plus élevé) ont également été objectivées. Les résultats confirment qu’une PS de durée modérée entraîne une altération des processus attentionnels pouvant être objectivée à la fois par les mesures comportementales et électrophysiologiques. Ces modifications sont présentes à toutes les étapes de traitement, tel que démontré par les effets touchant la P200, la N200 et la P300. Qui plus est, la PS affecte différemment les composantes à prédominance frontale et pariétale. / The objective of the present study was to assess the differential effects of sleep deprivation (SD) on cognitive functions relying on distinct cerebral networks, involved in the fronto-parietal attentional network, during a relatively simple and short cognitive task. Multi-sites recording event-related-potentials (ERP) were used in order to evaluate the effect of SD on rapid cognitive activity and its topographical correlates. The morning following a night of total SD and a night of sleep, 20 participants were administered a 3-stimuli visual oddball paradigm. Amplitudes and latencies of the P200 and N200 ERP components were analyzed as frontal indexes, whereas P300 was analyzed as a mixed frontal and parietal component. Following TSD, a non specific increase in P200 amplitude for the left hemisphere, as well as a loss of lateralisation in response to target stimuli, were observed. Contrarily, P300 amplitude was predominantly reduced in the parietal region in response to target stimuli. Moreover, N200 and P300 latencies were delayed non specific to the type of stimuli and performance (reaction time and accuracy) was altered. These results confirm the deleterious effect of a moderate duration SD on attention processes that can be objectified by means of behavioural and electrophysiological measures. Each stages of information processing was altered by SD, as shown by its effect on P2, N2 and P3 components. Moreover, SD affected differently components caracterized by a predominant frontal or parietal distribution.

Les PBDEs appartiennent à la famille des retardateurs de flamme bromés, substances massivement utilisés ces dernières décennies. Ces molécules sont aujourd’hui retrouvées de façon ubiquitaire dans l’environnement extérieur et intérieur. L’Homme est exposé à ces polluants par le biais de l’alimentation et de l’ingestion/inhalation de poussières ménagères ou industrielles contaminées. Leurs propriétés lipophiles et leur persistance sont à l’origine de leur bioaccumulation dans les matrices abiotiques et biologiques (lait, sérum…). Les travaux de recherche de cette thèse ont eu pour objectif d’évaluer l’impact d’une exposition à un polluant environnemental toxique et très répandu, le BDE-99, administré dans des conditions reflétant l’exposition humaine. Ainsi, les effets d’une administration de longue durée à des doses réalistes de BDE-99 (0,15, 1,5 et 15 µg/kg/j) ont été évalués au plan neurocomportemental et physiologique chez le rat mâle de souche Sprague-Dawley. Aucune altération de l’activité, de l’anxiété et des fonctions cognitives n’a été mise en évidence que les animaux aient été traités à l’âge adulte, à partir du sevrage ou à partir du 8ème jour de vie postnatale. Les seules variations comportementales significatives observées ont été des troubles transitoires de la coordination locomotrice ainsi qu’un retard d’une journée de l’ouverture des yeux chez les animaux traités avec le BDE-99 depuis l’âge de 8 jours. Au plan physiologique, aucune variation significative de l’évolution pondérale, des prises hydrique et alimentaire ainsi que du poids de plusieurs organes (foie, cerveau, reins, rate et thymus) n’a été observée quelle que soit la dose de BDE-99 administrée et la période d’exposition considérée. Ces résultats montrent donc que ce polluant administré chez le rat à des doses réalistes, reflétant celles auxquelles l’Homme est réellement exposé, n’est pas à même d’induire une toxicité neurocomportementale que les animaux aient contaminés à l’âge adulte ou bien lors de différentes phases du développement postnatal. Le fait d’avoir utilisé des doses correspondantes au niveau d’exposition environnemental est sans aucun doute à la base des discordances observées entre les résultats de ce travail et ceux des études publiées par ailleurs, soulignant ainsi la nécessité de réaliser des modèles d’exposition les plus pertinents possibles de la réalité humaine pour pouvoir conclure au mieux quant au risque lié à cette famille de contaminants pour la santé humaine. / PBDEs belong to flame retardants, substances heavily used in recent decades. These molecules are now found ubiquitously in the environment outside and inside. Humans are exposed to these pollutants through diet and ingestion/inhalation of household dust or contaminated industrial dust. Their lipophilic properties and their persistence are the cause of their bioaccumulation in abiotic and biological matrices (milk, serum ...). The research works of this thesis was aimed to assess the impact of exposure to a toxic environmental pollutant and very prevalent, BDE-99, administered in conditions reflecting the human exposure. Thus, the effects of long-term exposure to realistic doses of BDE-99 (0.15, 1.5 and 15 µg/kg/day) were evaluated in terms neurobehavioral and physiological in male Sprague-Dawley rats. No alteration of the activity, anxiety and cognitive function has been highlighted that the animals were treated in adulthood, from weaning or from the 8th day of postnatal life. The only significant behavioral variations observed were transient locomotor coordination disorders and a delay of one day of eye opening in animals treated with BDE-99 from the age of 8 days. On a physiological level, no significant variation in body weight change, food and water consumption and weight of several organs (liver, brain, kidneys, spleen and thymus) was observed whatever the dose of BDE-99 administered and the exposure period considered. These results show that this pollutant administered to rats at realistic doses, reflecting those to which humans are actually exposed, is not able to induce neurobehavioral toxicity that the animal are contaminated in adulthood or at different phases of postnatal development. The fact to have used corresponding the level of environmental exposure is undoubtedly the basis of discrepancies observed between the results of this work and those of the published studies elsewhere, underscoring the necessity to realize exposure models the most possible relevant in order to able to conclude at best about risk associated with this family of contaminants to human health.

In the theoretical part, this work deals with the problem of comparison between Feuerstein cognitive function and partial cognitive abilities which are mentioned at the Educational Interpretations of the WISC-III. Research study follows up changes in partial cognitive abilities which could be viewed as a consequence of FIE (Feuerstein Instrumental Enrichment) intervention lasting several months. By comparison of pre-test and post-test, which is realized by WISC-III and processed with Educational Interpretations of the WISC- III the study tries to describe impact of the method to child's cognitive functions as well as its school successfulness, self-concept, and behavior. Study also pursues possibility to use factor analysis of WISC-III for planning of the FIE intervention. Information was taken from tests, questionnaires for teachers, videos and records of FIE lessons. Research was realized at the Elementary school in a small town with 1700 inhabitants, nearby to Prague. This was the only school in this town. We noticed more or less significant changes in all areas of interest. In some cases, there was agreement in the test results and teacher's evaluation whereas in other there were differences. KEY WORDS Reuven Feuerstein, modifiability of intelligence, deficits of cognitive functions, mediated...

A Esclerose Múltipla (EM) é uma doença inflamatória autoimune caracterizada por desmielinização e degeneração do sistema nervoso central (SNC) duas a três vezes mais frequente em mulheres. A etiologia da EM é dividida em dois subtipos principais: o tipo remitente-recorrente (EMRR) mais comum, caracterizado por dois ou mais episódios de agravamento dos sintomas que envolvem diferentes locais do SNC, separados por pelo menos 1 mês e remisão dos sintomas e o tipo progressivo é a forma menos comum, caracterizada por um contínuo agravamento dos sintomas desde o início geralmente sem recaídas claras ou remissões. A presente pesquisa teve por objetivo avaliar o comprometimento da visão de cores e de sua relação com perdas de atenção, memória visual imediata, memória visual tardia, memória operacional e funções executivas dos portadores de esclerose múltipla tipo remitente recorrente. Método: participaram 41 pacientes com esclerose múltipla de idades entre 20 e 58 anos (35,4±12,2) e 37 controles com idade (34,7±12,1) e escolaridade semelhante. A discriminação de cores foi avaliada com o Cambridge Colour Test (CCT) e a avaliação de funções neuropsicológicas foram utilizados subtestes da bateria Cambridge Neuropsychological Testing Automated Battery (CANTAB) - Pattern Recognition Memory, Spatial Span, Spatial Recognition Memory, Information Sampling Task, Stop Signal Task e Rapid Information Processing; Escalas de Depressão e Ansiedade de Beck e Escala de Determinação Funcional da Qualidade de vida (DEFU). Resultados: A visão de cores está prejudicada de forma difusa em 24% dos pacientes com esclerose múltipla, tanto em pacientes com histórico de neurite óptica quando em pacientes que não tiveram neurite óptica. Na parte cognitiva, os pacientes demonstraram lentidão em executar as tarefas, comprometimento na atenção, na memória visual de curto e longo prazo, na memória operacional, na memória visuoespacial, além de lentidão no processamento de informações. Há uma relação entre alterações na visão de cores e alterações de memória visual somente em testes em que os estímulos são complexos e com inúmeros detalhes / Multiple sclerosis (MS) is an autoimmune inflammatory disease characterized by demyelination and central nervous system (CNS) degeneration. It is two times more frequent in women. It can be presented in two subtypes: the relapsing-remitting (RR), most common type, characterized by two or more episodes of focal disorders in different sites of the CNS, and remission of the symptoms; and the progressive subtype, less common, characterized by a continuous worsening of the symptoms, since the beginning, usually with no remissions. The present research evaluated color vision impairment and its relationship to attention loss, short-term memory, long-term memory, working memory and executive function in patients with the relapsing-remitting MS type. Methods: 41 patients with multiple sclerosis (20 to 58 years, 35.4 ± 12.2 in average) and 37 controls matched to age (34.7 ± 12.1 in average) and years of education participated of the study. Color vision was tested using the Cambridge Colour Test (CCT) and the neuropsychological assessment was performed using tests of the Cambridge Neuropsychological Testing Automated Battery (CANTAB) - Pattern Recognition Memory, Spatial Span, Spatial Recognition Memory, Information Sampling Task, Stop Signal Task, Rapid Information Processing the Beck Depression and Anxiety Inventories and the Functional Assessment of Multiple Sclerosis quality of life instrument. Results: Color vision was diffusely impaired in 24% of the MS patients, with or with no history of optic neuritis. Patients also showed a delay during the tasks execution, impairment in attention, short and long-term visual memory and working memory, and slowness in the information processing. There was a relationship between color vision loss and visual memory impairment, but only in tests with complex and highly detailed stimuli

L’objectif de la présente étude visait à évaluer les effets différentiels de la privation de sommeil (PS) sur le fonctionnement cognitif sous-tendu par les substrats cérébraux distincts, impliqués dans le réseau fronto-pariétal attentionnel, lors de l’administration d’une tâche simple et de courte durée. Les potentiels évoqués cognitifs, avec sites d’enregistrement multiples, ont été prévilégiés afin d’apprécier les effets de la PS sur l’activité cognitive rapide et ses corrélats topographiques. Le matin suivant une PS totale d’une durée de 24 heures et suivant une nuit de sommeil normale, vingt participants ont exécuté une tâche oddball visuelle à 3 stimuli. L’amplitude et la latence ont été analysées pour la P200 et la N200 à titre d’indices frontaux, tandis que la P300 a été analysée, à titre de composante à contribution à la fois frontale et pariétale. Suite à la PS, une augmentation non spécifique de l’amplitude de la P200 frontale à l’hémisphère gauche, ainsi qu’une perte de latéralisation spécifique à la présentation des stimuli cibles, ont été observées. À l’opposé, l’amplitude de la P300 était réduite de façon prédominante dans la région pariétale pour les stimuli cibles. Enfin, un délai de latence non spécifique pour la N200 et la P300, ainsi qu’une atteinte de la performance (temps de réaction ralentis et nombre d’erreurs plus élevé) ont également été objectivées. Les résultats confirment qu’une PS de durée modérée entraîne une altération des processus attentionnels pouvant être objectivée à la fois par les mesures comportementales et électrophysiologiques. Ces modifications sont présentes à toutes les étapes de traitement, tel que démontré par les effets touchant la P200, la N200 et la P300. Qui plus est, la PS affecte différemment les composantes à prédominance frontale et pariétale. / The objective of the present study was to assess the differential effects of sleep deprivation (SD) on cognitive functions relying on distinct cerebral networks, involved in the fronto-parietal attentional network, during a relatively simple and short cognitive task. Multi-sites recording event-related-potentials (ERP) were used in order to evaluate the effect of SD on rapid cognitive activity and its topographical correlates. The morning following a night of total SD and a night of sleep, 20 participants were administered a 3-stimuli visual oddball paradigm. Amplitudes and latencies of the P200 and N200 ERP components were analyzed as frontal indexes, whereas P300 was analyzed as a mixed frontal and parietal component. Following TSD, a non specific increase in P200 amplitude for the left hemisphere, as well as a loss of lateralisation in response to target stimuli, were observed. Contrarily, P300 amplitude was predominantly reduced in the parietal region in response to target stimuli. Moreover, N200 and P300 latencies were delayed non specific to the type of stimuli and performance (reaction time and accuracy) was altered. These results confirm the deleterious effect of a moderate duration SD on attention processes that can be objectified by means of behavioural and electrophysiological measures. Each stages of information processing was altered by SD, as shown by its effect on P2, N2 and P3 components. Moreover, SD affected differently components caracterized by a predominant frontal or parietal distribution.

It is imperative to prepare South African learners to participate and function confidently within the context of a rapidly changing world. The curriculum of the South African Education System emphasises the significance of optimising learners‟ cognitive development as early as pre-school age to enable them to become creative and critical citizens who lead purposeful lives in a safe and prejudice-free environment. Despite continuous efforts by educators to optimise cognitive development, recently executed research studies indicate that cognitive development has not been adequately optimised in South African schools. This study was undertaken to establish the cognitive development level (cognitive and meta-cognitive skills and strategies, cognitive functions and non-intellective factors) of Grade R-learners and to determine the effect of an intervention programme, the Cognitive Enhancement Programme for Pre-schoolers (CEPP), on their cognitive development. By means of a literature study, I investigated whether, to what extent the cognitive development of Grade R-learners was taking place, and established which cognitive and meta-cognitive thinking skills and strategies, cognitive functions and non-intellective factors are required for effective cognitive development among Grade R-learners. In addition to this, the role of mediation for optimising cognitive development was investigated. A concurrent embedded mixed methods design was conducted in the implementation of the research. Intervention research within a quasi-experimental research design was applied. The data collection by means of a quantitative strategy (quasi-experimental research) and qualitative strategy (observation study) was executed simultaneously. By means of convenient sampling, one Grade R-class with twenty learners was subjected to a pre-test to establish their cognitive developmental level. The test results as well as the observations conducted during the pre-test revealed that the learners experienced problems related to their cognitive development. Ten of the twenty learners were then divided purposively based on their test performance into two experimental groups, Experimental Group A and Experimental Group B consisting of five participants each. Experimental group A and Experimental Group B took part in the CEPP intervention based on the principles of mediation on a rotational basis over a period of twelve weeks, during which intentional attempts were made to optimise their cognitive development. Both groups completed a post-test and delayed post-test (retention) to determine the effect of the CEPP intervention on their cognitive development. In addition to the test results, observations in the form of structured running and anecdotal records and reflective notes were utilised to understand the nature and quality of the cognitive development of the learners better. Furthermore, the effect of the intervention on their cognitive development was established. The cognitive development of Grade R-learners who participated in this study was optimised, which is a clear indication that cognitive capacity can be optimised when instruction is based on the principles of mediation / PhD, Teaching and Learning, North-West University, Vaal Triangle Campus, 2012