Cognitive training does not enhance general cognition

Due to potential theoretical and societal implications, cognitive training has been one of the most influential topics in psychology and neuroscience. The assumption behind cognitive training is that one’s general cognitive ability can be enhanced by practicing cognitive tasks or intellectually demanding activities. The hundreds of studies published so far have provided mixed findings and systematic reviews have reached inconsistent conclusions. To resolve these discrepancies, we carried out several meta-analytic reviews. The results are highly consistent across all the reviewed domains: minimal effect on domain-general cognitive skills. Crucially, the observed between-study variability is accounted for by design quality and statistical artefacts. The cognitive-training program of research has showed no appreciable benefits, and other more plausible practices to enhance cognitive performance should be pursued

Innate talents: reality or myth?

Talents that selectively facilitate the acquisition of high levels of skill are said to be present in some children but not others. The evidence for this includes biological correlates of specific abilities, certain rare abilities in autistic savants, and the seemingly spontaneous emergence of exceptional abilities in young children, but there is also contrary evidence indicating an absence of early precursors of high skill levels. An analysis of positive and negative evidence and arguments suggests that differences in early experiences, preferences, opportunities, habits, training, and practice are the real determinants of excellence

Birefringent fibre ring resonators: Analysis and stabilization techniques

The polarization stability of single-mode fibre resonators has been recognized as a potential problem in their operation. One method to overcome the polarization drift is to use a polarization-maintaining optical fibre, in the resonator system. Even this kind of resonators, still suffer from environmentally-induced polarization instabilities. Depending on the type of resonator, these instabilities are manifest as a split resonant dip, reduced finesse, reduced fringe modulation, fringe asymmetry, and unequal spacing between successive fringes. If we assume that a non zero amount of polarization crosstalk at the coupler is inevitable, then there is only one ideal type of resonator which is free from instabilities: a resonator made from polarizing fibre (or one that incorporates a perfectly aligned polarizer in the loop). The fringe shape variation can be reduced if the resonator is made with a deliberate 90 deg. axis twist at the splice or coupler, or if it is made with a polarization-selective coupler. No practical technique has been demonstrated so far, for producing consistently stable resonators with high finesse, using birefringent fibre. This is because the tolerable amount of coupler polarization crosstalk is very small, and the above ideal form is not easily made. It is therefore important to compare the output stability of the different resonator types as well as to investigate possible techniques for passive or active stabilization of the output. In this thesis work we have developed a experimentally verifiable resonator model that can be applied to different resonator types with minor modifications. We have derived tolerances for the coupler polarization crosstalk, splice alignment, and input polarization mode purity necessary for optimum operation of each type. A fringe shape stabilization system has been constructed, for use with fibre ring resonators with power exchange between the birefringent axes. The system works by keeping the depth of successive resonant dips equal, through a feedback electronic servo system, that controls the fibre birefringence. Two schemes for controlling the fibre birefringence are investigated

Action control in uncertain environments

A long-standing dichotomy in neuroscience pits automatic or reflexive drivers of behaviour against deliberate or reflective processes. In this thesis I explore how this concept applies to two stages of action control: decision-making and response inhibition. The first part of this thesis examines the decision-making process itself during which actions need to be selected that maximise rewards. Decisions arise through influences from model-free stimulus-response associations as well as model-based, goal-directed thought. Using a task that quantifies their respective contributions, I describe three studies that manipulate the balance of control between these two systems. I find that a pharmacological manipulation with levodopa increases model-based control without affecting model-free function; disruption of dorsolateral prefrontal cortex via magnetic stimulation disrupts model-based control; and direct current stimulation to the same prefrontal region has no effect on decision-making. I then examine how the intricate anatomy of frontostriatal circuits subserves reinforcement learning using functional, structural and diffusion magnetic resonance imaging (MRI). A second stage of action control discussed in this thesis is post-decision monitoring and adjustment of action. Specifically, I develop a response inhibition task that dissociates reactive, bottom-up inhibitory control from proactive, top-down forms of inhibition. Using functional MRI I show that, unlike the strong neural segregation in decision-making systems, neural mechanisms of reactive and proactive response inhibition overlap to a great extent in their frontostriatal circuitry. This leads to the hypothesis that neural decline, for 4 example in the context of ageing, might affect reactive and proactive control similarly. I test this in a large population study administered through a smartphone app. This shows that, against my prediction, reactive control reliably declines with age but proactive control shows no such decline. Furthermore, in line with data on gender differences in age-related neural degradation, reactive control in men declines faster with age than that of women

How Effective is the Invisible Hand? Agricultural and Food Markets in Central and Eastern Europe

Since the seminal work of Adam Smith, markets have been considered an efficient tool for co-ordinating the behaviour of economic agents. The basic characteristic of a market economy is that the complex system of interaction among individuals is not centrally coordinated. Under the assumption of profit and utility maximisation (and a whole set of assumptions about the institutional framework), relative prices and their change over time provide the signals that guide, like an invisible hand, the allocation of resources, i.e., the structure of production and the intensity of input use in the various production processes. They do this by co-ordinating the activities of economic agents, i.e., of resource owners, producers, intermediaries, traders, and consumers. After system change in the former Soviet Union and in Central and Eastern Europe (CEE) central economic planning had to be replaced by other forms of co-ordination. The general direction in all transition countries was towards a market economy, but the speed and depth of reforms towards an environment in which markets can evolve differed largely between countries, sectors and between different phases during the past 15 years. IAMO Forum 2005 focuses on this development and discusses the functioning of markets, the requirements for this, and the advantages and disadvantages of other co-ordination mechanisms under different environments in the agricultural and food sectors in Central and Eastern Europe. CEE agri-food markets deserve researchers' and policy makers' attention for several reasons. Two of them regard the high demand for support to policy decisions that aim to stimulate economic and social development in the region. In most CEE countries, the significance of the agricultural and food sector is relatively high with respect to income and employment. In particular, rural areas can benefit from the development of this branch of the economy. Also, there is marked indication that agri-food markets in CEE are not ensuring exchange as frictionless as possible. This means that large benefits can be expected if potential improvements of the economic environment are implemented and if individual agents adapt optimally to that environment. Another motivation for economic research on transition countries is that we are looking at a huge region that started almost as a vacuum with regard to institutional settings. This means that a wide range of substantially different settings were introduced in the respective countries, and were only weakly confined by political rigidities or path dependencies. From a distant perspective, the repeated fundamental shifts in recent economic policies almost evoke the impression of a trial and error approach. The consequences of distinctively different options (across countries and periods) can be observed in a way almost similar to a laboratory situation. Such unique opportunity has attracted economists, particularly those interested in institutional economics, to conduct research on CEE. However, this also means that the experiences made in CEEC can enhance the general understanding of what markets can do and what the limitations of market coordination are. This volume contains selected contributions presented at IAMO Forum 2005 and gives an overview of the major topics discussed there. Partial analyses of specific economic problems usually abstract from the general economic framework which is assumed to be more or less constant as expressed in ceteris paribus clauses. Oftentimes, the set of institutional conditions is even assumed to be sufficiently well-described by the framework used in neoclassical models. Particularly for transition countries, this has frequently led to spurious results because crucial aspects of the framework actually in place were not considered, and sometimes were not even thought of. An extreme and very obvious example is the neglect of the effects of the replacement of monetary by nonmonetary exchange in phases of a barter economy. There is no generic approach to avoid unintended omission of crucial framework conditions, but it must generally be emphasised that a broad look at the various interdependent markets and at the entire socioeconomic context of a country is needed before going into detail. Descriptive analyses of the situation in various markets form part of such a broad look. The contributions of POPP, FERTÃ et al., WILKIN et al., and HEIN in the chapter Selected analyses from CEEC provide excellent examples, and focus on market developments in new EU member countries. On the one hand, the papers show the heterogeneity of problems e.g. due to largely differing farm structures. On the other hand, several common patterns can be observed: The market shares and power of large processors and retailers (hypermarkets, etc.) are increasing. Also, international (especially intra-EU) trade in commodities has increased in response to CAP-induced price harmonisation. Both tendencies weaken the market position of farmers, particularly small entities which cannot supply in volumes sufficient for large processing and trade firms. Within the food industry concentration increased as many smaller firms could not comply with EU processing standards and had to quit the market. The increased size and specialization of large producers, as well as of large processors, made many of those firms co-ordinate business with each other through long-term contractual agreements rather than by relying on spot markets. This tendency is very distinct in the fruit and vegetable sector, as WILKINâs contribution describes. Two contributions draw attention to the institutional framework itself, mainly by looking at circumstances which prevent market allocation from leading to an optimal outcome. HOBBS describes factors that impede investment and growth by drawing on transaction cost economics. Situations typical for transition countries are highlighted where e.g. transparency is not sufficient or the existence and reliable enforcement of contract or corporate law are not guaranteed. NUPPENAU stresses the need for the appropriate and precise formulation of land property rights, which should evoke a balance between governance and exclusion. The importance of appropriate and reliable institutions to avoid flaws is emphasised. But even with suitable institutions, transaction costs cannot be reduced to zero. The main reason for this is that since agents may gain form a head start of information, incentives to reveal their knowledge are quite restricted. Furthermore, some of the information required to make correct decisions is not available. This especially concerns information regarding all future contingencies. An uncertain future and the asymmetric distribution of information impose special problems when decisions have long-term effects and agents are linked together through investment decisions. This offers possibilities for opportunistic behaviour, i.e., when an agent behaves in a way that allows him to extract rents from the partners' activities. The friction induced in such situations may result in a market outcome that is biased by transaction costs. Mitigating this bias should be a goal of public policy but it is also in the interest of (at least some of the) private agents involved. This issue is discussed in more detail in the papers dealing with alternative governance structures. A number of contributions to IAMO Forum highlight approaches for measuring the well-functioning of markets. While studies that aim to directly measure transaction costs are very rare and are necessarily limited to comparing only very specific portions of transaction costs, most studies focus on indirect indicators. These usually start from the idea that in a well-functioning, competitive market any supply or demand shocks are reflected in price changes, not only in the particular market where the shock occurs but also in other, related markets, i.e., in different locations or at different stages of the production and marketing chain. Consequently, an approach for assessing the functioning of markets is to compare price differentials with processing-, marketing- or transfer-costs, or â since these costs are usually difficult to quantify â to observe price differentials over time. Accepting the assumption that the costs reflected by price differentials are more or less constant (or stationary) over the observed time span, any additional price changes or a lack of price co-movement is interpreted as an indication for insufficiently connected or insufficiently functioning markets. Three contributions in the chapter Analytical approaches for measuring market efficiency describe analyses which mainly focus on the vertical dimension, i.e., between market stages. BOJNEC, in his descriptive price analysis for several agricultural products in Slovenia since 1991, finds a heterogeneous development of the farm gate/consumer price spread: The processing and marketing margins increased for wheat and beef while they declined for grapes (processed to wine), sugar and poultry. BRÃMMER and ZORYA, as well as BAKUCS and FERTÃ, use cointegration analysis to describe the degree and nature of vertical price integration in the Ukrainian wheat market and the Hungarian pork market, respectively. Both studies find that price changes are transmitted vertically, that there is a tendency to "correct" any deviations from some underlying equilibrium price-relationship. However, such error correction mechanisms are found not to be a constant, universal force. In the Hungarian paper, it could only be found for a sub-period of the observed time span, excluding the highly volatile early 1990s. Also, equilibrium was found to be achieved by adjustment of farm gate prices only while the retail prices were found to be exogenous, i.e., not responding to any disequilibrium. The paper on Ukraine shows that adjustment processes between wheat and wheat flour prices cannot be sufficiently described by a constant error correction mechanism for the period 2000 to 2004. In fact, four different regimes of adjustment processes were found to have been in force, reflecting particular phases of largely differing market situations and political interventions. The functioning of markets depends on several crucial conditions. One of these conditions concerns the availability of information. Only if agents have perfect and complete information will the exchange lead to an outcome in which no individual can be better off without reducing the welfare of others. However, in the real world this condition regarding information is not fulfilled. Information is not perfect, since the future cannot be predicted with certainty. Incomplete information results from, first, not all information being revealed, and second, individuals not possessing the mental capacity to collect and process all information. Moreover, because of its asymmetric distribution, information can be regarded as a resource that can be exploited by agents. This means that there are incentives to hamper the diffusion of information to the public domain. In general, the more uncertain the future is and the more information is tacit, the worse markets will function, and the more beneficial become alternative mechanisms of coordination. Three papers dealing with this issue of organisational choice. HANF focuses on governance structures within supply chain networks that are appropriate for allowing an optimal flow of information between the involved individuals while retaining the necessary hierarchy for efficient implementation of strategic decisions. MAACKâs analysis shows that there is strong mutual interest between producers and processors of berry fruits to reduce marketing and procurement risk, respectively. This can be achieved by switching from spot market exchange to contractual supply agreements. A prerequisite for such agreements is that a well-balanced distribution of risks and risk premiums between the farmer and processor is implemented. This means that processors, who â facing a multitude of small producers â are used to opportunities for exerting market power, have to agree to cover part of the production risk through appropriate contractual clauses. Finally, BALINT looks at the various marketing channels used by Romanian farmers and finds that a self-enforcing dualism exists. For commercially-oriented farmers who can supply large quantities, marketing directly to traders, wholesalers and processors is most favourable and involves relatively low transaction costs. Although this form of supply-relationship is usually not based on contractual agreements, it can still be characterised by a certain stability over time. In contrast, small farmers whose production does not considerably exceed the subsistence level incur relatively high (per unit) transaction costs in selling their produce on local markets and to other farmers. Another aspect of organisational choice is the question of whether ownership of production factors is transferred or only the right to use them temporarily. The uncertainty of future developments implies that the possession of resources cannot be only regarded from the point of view of income generation at a certain point in time. With perfect foresight, there is no difference whether a factor is rented or purchased, because the remuneration would be the same. This perfect substitutability is no longer given when the future is uncertain. Income generation, then, is only one feature of ownership. Additional aspects such as insurance, wealth, and speculation as motivations for possession affect the value of ownership and thus shift the demand and supply curves of the factor. HURRELMAN picks up this issue in her analysis of the Polish land market and shows the impact of additional grounds for valuing property on the decision to rent or to buy land. Uncertainty may also affect the specialization of factor use. Allocating a factor of production to different production activities reduces the risk of income instabilities, but at the cost of specialization gains through economics of scale. Moreover, the decision on income combination is â besides risk â affected by a complex interaction of other determinants. GLAUBEN et al., analyse these interactions for the case of part-time farming in China and show how the decision of income combination is affected by household characteristics, human capital and other variables. Incomplete and imperfect information not only causes individuals to choose optimal governance modes, often it is also understood as a call for government intervention. The selected papers in the chapter on policy intervention plead for careful selection and coherent implementation of policy instruments. BENNER, as well as KUHN, highlight the significance of information diffusion and argue in favour of government intervention in this area. However, both emphasise that these interferences should be used carefully and be adjusted to specific market failures. Both argue that setting up information systems would improve the functioning of markets. BENNER also discusses possible negative impacts if governments that engage in setting up and enforcing product and process standards try, at the same time, to foster a sector like agriculture through support in marketing. The latter activity affects the governmentâs (crucial) credibility in the first activity. KUHN points to negative welfare effects and budgetary requirements of an intervention system which is implemented to increase price stability. Moreover, when a government intervenes in market allocation or intends to provide rules that should facilitate the exchange on markets, it has to take into account that the new regulation has to be implemented in a coherent manner. This requires the various policy regulations and institutional settings to be complementary and not cause frictions which hamper the functioning of the system. LERMAN and SHAGAIDA highlight this aspect in their discussion of the Russian land market, where bureaucracy and high costs for the registration of property rights can be regarded as a major cause of the low number of land transactions. However, since economic activities take place in a dynamic environment, the comparative static point of view may lead to inappropriate policy formulation. WANDEL discusses this aspect in the context of competition policy. From a comparative static point of view, market power has to be assessed negatively because of the distortions of resource allocation. However, monopoly profits are an indicator of extra rents and thus provide incentives for market entry. On the one hand, this thread may lead to special pricing schemes and/or to the accelerated development of technological change so that a monopolist can consolidate its market position. But it is possible, on the other hand, that market entry may in fact happen. In this case, one would observe structural change, which would be accompanied by an improved use of resources. This in turn means that competition policy should not be oriented towards an optimal market structure but towards the facilitation of market entry so that competition can discover market opportunities and determine the optimal structure of the market. The present volume shows the wide range of interesting and controversial topics that are concerned when looking at co-ordination, particularly on markets in CEE agri-food sectors. It remains a hope that the heterogeneity and dynamics of the developments will decrease as successful constellations of framework conditions, organisational choices and individual behaviour become more and more obvious and widespread in the region. Conversion to sustainable, balanced patterns might take place, but this cannot be taken for granted. However, chances for such development are better the more stable and balanced political developments, as well as international co-operation, become. We hope that the academic community will contribute towards such goal.Agribusiness, Community/Rural/Urban Development, Industrial Organization, International Development, Labor and Human Capital, Land Economics/Use, Political Economy,

Cognitive and neuronal bases of expertise

This thesis examines the cognitive and neural bases of expertise. In so doing, several psychological phenomena were investigated-imagery. memory and thinking-using different tasks, and a variety of techniques of data gathering, including standard behavioural experiments, questionnaires, eye-movement recording, and functional magnetic resonance imaging (fMRI). Chess players participated in all the studies, and chess tasks were used. The data confirmed the versatility and power of chess as a task environment, since the results provided fruitful information for the understanding of different human cognitive processes. The role of practice in this domain of expertise was examined. The strong view that extended deliberate practice is a necessary and sufficient condition for the acquisition of expert performance, did not receive support in this thesis. Alternatively, a less extreme position was adopted: extended practice is a necessary, but not a sufficient condition for the acquisition of expert performance. A search for individual differences in factors unrelated to chess practice was carried out. The sources of these individual differences, as well as the cognitive abilities in which individual differences may exist, were considered. One of the sources-the age at which serious practice starts-was a good predictor of chess skill. Handedness, which is supposed to be determined by environmental factors in utero, slightly differentiated chess players from non-players, but no differences in this variable were found between strong and the weak players. Regarding the cognitive abilities, chess players performed slightly better than the non-chess players in a spatial task. Individual differences were also considered within a single leyel of expertise-master level. Differences in forgetting rate in long-term memory and reaction time were observed for one of the masters. These results contributed to the improvement of an extant theory of expertise-template/CHREST [CHunks and REtrieval STructures] theory-by estimating values for some of its parameters based on the empirical data obtained, and by proposing the addition of a spatial short-term memory

Dealings on the Dark Web: An Examination of the Trust, Consumer Satisfaction, and the Efficacy of Interventions Against a Dark Web Cryptomarket

Abstract Objective. The overarching goal of this thesis is to better understand not only the network dynamics which undergird the function and operation of cryptomarkets but the nature of consumer satisfaction and trust on these platforms. More specifically, I endeavour to push the cryptomarket literature beyond its current theoretical and methodological limits by documenting the network structure of a cryptomarket, the factors which predicts for vendor trust, the efficacy of targeted strategies on the transactional network of a cryptomarket, and the dynamics which facilitate consumer satisfaction despite information asymmetry. Moreover, we also aim to test the generalizability of findings made in prior cryptomarket studies (Duxbury and Haynie, 2017; 2020; Norbutas, 2018). Methods. I realize the aims of this research by using a buyer-seller dataset from the Abraxas cryptomarket (Branwen et al., 2015). Given the differences between the topics and the research questions featured, this thesis employs a variety of methodological techniques. Chapter two uses a combination of descriptive network analysis, community detection analysis, statistical modelling, and trajectory modelling. Chapter three utilizes three text analytic strategies: descriptive text analysis, sentiment analysis, and textual feature extraction. Finally, chapter four employs sequential node deletion pursuant to six law enforcement strategies: lead k (degree centrality), eccentricity, unique items bought/sold, cumulative reputation score, total purchase price, and random targeting. Results. Social network analysis of the Abraxas cryptomarket revealed a large and diffuse network where the majority of buyers purchased from a small cohort of vendors. This theme of preferential selection of vendors on the part of buyers is repeated in other findings within this study. More generally, the Abraxas transactional network can then be viewed as set of transactional islands as opposed to a large, densely connected conglomeration of vendors and buyers. With regard buyer feedback, buyers are generally pleased with their transactions on Abraxas as long as the product arrives on time and is as advertised. In general, vendors have a relatively low bar to achieve when it comes to satisfying their customers. Based on the results of the sequential node deletion, random targeting was found to be ineffective across the five outcome measures, producing minimal and a slow disruptive effect. Finally, these strategies are based on a power law where a small percentage of deleted nodes is responsible for an outsized proportion of the disruptive impact. Conclusion. As with all applied research examining emergent phenomena, this thesis lends itself to a more refined understanding of dark web cryptomarkets. While the results and conclusions drawn from these results are not perfectly generalizable to all cryptomarkets, they should serve to inform law enforcement on the dynamics which undergird these markets. To this extent, a sombre consideration of trust, consumer satisfaction, and tactical effectiveness of interventions is a necessary step towards the development of more effective countermeasures against these illicit online marketplaces. For law enforcement to be more effective against cryptomarkets, it is advised that an evidence-based approach be taken

A Rainbow in Deep Network Black Boxes

We introduce rainbow networks as a probabilistic model of trained deep neural networks. The model cascades random feature maps whose weight distributions are learned. It assumes that dependencies between weights at different layers are reduced to rotations which align the input activations. Neuron weights within a layer are independent after this alignment. Their activations define kernels which become deterministic in the infinite-width limit. This is verified numerically for ResNets trained on the ImageNet dataset. We also show that the learned weight distributions have low-rank covariances. Rainbow networks thus alternate between linear dimension reductions and non-linear high-dimensional embeddings with white random features. Gaussian rainbow networks are defined with Gaussian weight distributions. These models are validated numerically on image classification on the CIFAR-10 dataset, with wavelet scattering networks. We further show that during training, SGD updates the weight covariances while mostly preserving the Gaussian initialization.Comment: 56 pages, 10 figure

Functional Magnetic Resonance Imaging

"Functional Magnetic Resonance Imaging - Advanced Neuroimaging Applications" is a concise book on applied methods of fMRI used in assessment of cognitive functions in brain and neuropsychological evaluation using motor-sensory activities, language, orthographic disabilities in children. The book will serve the purpose of applied neuropsychological evaluation methods in neuropsychological research projects, as well as relatively experienced psychologists and neuroscientists. Chapters are arranged in the order of basic concepts of fMRI and physiological basis of fMRI after event-related stimulus in first two chapters followed by new concepts of fMRI applied in constraint-induced movement therapy; reliability analysis; refractory SMA epilepsy; consciousness states; rule-guided behavioral analysis; orthographic frequency neighbor analysis for phonological activation; and quantitative multimodal spectroscopic fMRI to evaluate different neuropsychological states