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We examined how explicit instructions to encode visual context information accompanying visually-presented unrelated target words affected later recognition of the targets presented alone, in younger and older adults. In Experiments 1 and 3, neutral context scenes, and in Experiments 2 and 4, emotionally salient context scenes, were paired with target words during encoding. Experiments 1 and 2 data were collected using within subject design; in Experiments 3 and 4 we used a between subjects design. Across all four experiments, instructions to explicitly make a link (associate) between simultaneously presented context and target words always led to significantly better recognition memory in both younger and older adults compared to deep or shallow levels of processing (LoP) instructions for the context information. In all experiments the age-related deficit in overall memory remained. There was no consistent difference in the effect of a shallow versus deep processing of context in the first three experiments in young adults, although a standard LoP effect, with better memory performance following deep than shallow processing, was demonstrated with both age groups in Experiment 4. Results suggest that an instruction to explicitly link target words to context information will significantly and consistently improve memory recognition for targets. This was demonstrated in all four experiments, in both younger and older adults. Importantly, results suggest that memory in older adults can be improved with specific instructional manipulations during encoding.

Over two decades of patient and neuroimaging data have provided increasing support for a role of the posterior cerebellum in cognition, particularly attention. Contralateral connections between the prefrontal cortex and the cerebellum are a probable basis for this effect. It is the purpose of this thesis to understand the contribution of the fronto-cerebellar system to cognitive and attentional processes. The first aim of this thesis was to localize areas of the cerebellum that participate in non-motor behaviour. After transient disruption of cerebellar activity using continuous theta burst stimulation (cTBS), a form of transcranial magnetic stimulation, Study 1 and 2 identified the right posterior-lateral cerebellum as a contributor to a network involved in two non-motor tasks; word generation and the attentional blink. The aim of Study 3 was to investigate if manipulating task demands increased fronto-cerebellar recruitment. The final study of this thesis employed electroencephalography (EEG) and cTBS to probe the neural events disrupted during the attentional blink task when the left frontal- right cerebellar system was transiently disrupted. Understanding the manner in which these neural events are affected by transient perturbation is integral to the understanding of the fronto-cerebellar contribution to cognitive and attentional processes. Together these studies help elucidate the role of the fronto-cerebellar system in non-motor functions.

Everyday experience suggests that certain people can find their way to a destination easily, while others have considerable difficulty. This dissertation focused on gaining a greater understanding of navigational strategies that can facilitate or hinder an individual’s wayfinding performance. The first study was conducted to gain a broad idea of various factors that may influence navigational performance. Participants were guided through a building and then asked to find their way to a destination. It was found that good navigators made fewer errors in traversing a learned route than did poor navigators. They were also better at recognizing landmarks they had seen along the route, recalling the appropriate directions to be turned at each landmark, and at drawing the correct pathways on a map drawing task. A discriminant analysis revealed that the best predictor of determining navigational performance was the ability to form spatial relationships between landmarks. Results from the first study demonstrated that good navigators were better at determining spatial relationships between landmarks, but it did not address whether this was due to spatial relationships between distances and/or angles. The focus of the second study was to gain a greater understanding of the degree to which distance and angular information are used by good and poor navigators in determining spatial relationships between landmarks. Results showed that neither a distance nor an angular strategy were preferred in either group of wayfinders. An analysis of navigators initial heading angle error to a target location suggested that good wayfinders may be more efficient at finding their way because they appear to plan routes prior to initiating self-locomotion. Such pre-planning was confirmed by the fact that good wayfinders’ initial heading direction error was significantly less than in poor wayfinders. Poor wayfinders appear to head in a random direction and then attempt to determine target locations. The use of landmark information may be useful in certain contexts, but this may not always be the most efficient strategy. The last experiment was aimed at determining whether good navigators adjust strategies used (landmark vs. street), depending on contextual factors. Differences in strategies used were not found, however the results suggest that good navigators appear to be more skilled at navigating in environments rich with streets compared to poor wayfinders. Good and poor navigators were equally skilled at navigating in environments rich in landmarks. It appears that the ability to determine spatial relationships between landmarks is the strongest predictor of navigational performance compared to a wide range of other navigational skills.

Over two decades of patient and neuroimaging data have provided increasing support for a role of the posterior cerebellum in cognition, particularly attention. Contralateral connections between the prefrontal cortex and the cerebellum are a probable basis for this effect. It is the purpose of this thesis to understand the contribution of the fronto-cerebellar system to cognitive and attentional processes. The first aim of this thesis was to localize areas of the cerebellum that participate in non-motor behaviour. After transient disruption of cerebellar activity using continuous theta burst stimulation (cTBS), a form of transcranial magnetic stimulation, Study 1 and 2 identified the right posterior-lateral cerebellum as a contributor to a network involved in two non-motor tasks; word generation and the attentional blink. The aim of Study 3 was to investigate if manipulating task demands increased fronto-cerebellar recruitment. The final study of this thesis employed electroencephalography (EEG) and cTBS to probe the neural events disrupted during the attentional blink task when the left frontal- right cerebellar system was transiently disrupted. Understanding the manner in which these neural events are affected by transient perturbation is integral to the understanding of the fronto-cerebellar contribution to cognitive and attentional processes. Together these studies help elucidate the role of the fronto-cerebellar system in non-motor functions.

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This thesis represents two lines of investigation that as a whole integrate physiology and ecology of infectious diseases. While each chapter is a distinct body of work, these studies are linked in that both focus on extrinsic or intrinsic factors influencing hosts’ susceptibility to infection, as well as hosts’ potential to transmit disease. In chapter one, I used a meta-analysis as a tool to review what is known about the stress-linked susceptibility hypothesis, which poses that persistent activation of the stress axis might result in increased disease susceptibility in wild animals, mainly as a result of allostatic overload and the immunosuppressive actions of stress hormones. My goal in evaluating the strength of association between distinct stressors and health indices in wildlife populations was manifold. First, I wanted to investigate which specific stressors are more likely to increase disease susceptibility in wild animals. Second, I was interested in the reliability of stress biomarkers as indicators of stress-induced immunosuppression or disease susceptibility. Finally, I used this chapter as a bridge for my second chapter by addressing how “fast-paced” and “slow-paced” phenotypes within wild populations cope differently with stressors, thus also differentially altering epizootic risk. My meta-analysis indicated that the highly variable outcomes of ecological studies can be attributed to several factors, ranging from possible erroneous classification of stimuli as physiological stressors to a lack of consensus on the endocrine profiles of stressed animals. The second chapter of this work consists of an empirical investigation of the pace-of-life (POL) hypothesis in the context of host disease susceptibility and transmissibility. Individuals with a fast-paced life history often exhibit relatively high metabolic rates and investment in growth, development, and reproduction. To support these faster rates, they often exhibit decreased investment in immunity, as well as associated bold behaviors for increased foraging and competiveness to ensure access to resources. These associated functional physiological and behavioral traits likely also influence exposure and susceptibility to pathogens, and infectiousness; factors central to disease dynamics. Through transmission trials using ranavirus and larval amphibians as a model system, I found that repeatable latency-to-food profiles of larval hosts, which characterize a POL axis associated with development and metabolic rates, were predictive of individual susceptibility and infectiousness. Faster-paced larval amphibians had greater exposure to pathogens (contacts), higher risk of infection (susceptibility), and shed greater pathogen populations when infected. Through these findings, I argue that The POL framework can allow for a priori identification of individual hosts that are more likely to spread infectious disease and may provide insight into understanding and potentially managing disease outbreaks that threaten wildlife and humans alike.

This thesis is a sociological history of the making of behavioural economics. Behavioural economics is a discipline in which economists draw on psychological knowledge and approaches to understand economic behaviour. The narrative begins with the lives and work of psychologists Daniel Kahneman and Amos Tversky in the newly established state of Israel. It then moves from the making of the so called Heuristics and Biases Programme in the 1970’s to the privately funded Behavioural Economics Program in the USA in the 1980’s. Using a blend of analysis of archival documents, published material, and interviews I seek to understand the formation of the discipline of behavioural economics by applying the notion of a psychology)of)error as an analytical tool. The small number of historians who have studied behavioural economics have all identified a concern with human error as a crucial element of its intellectual makeup. I take this observation further by arguing that both Kahneman and Tversky’s Heuristics and Biases Programme and behavioural economics are psychologies) of) error because the object to be explained in both fields was restricted to behavioural deviations from a normative core. In the case of Heuristics and Biases that normative core consisted of a blend of statistical and logical norms imported from traditional decision theory about what constituted rational decision making. In the case of behavioural economics the normative core was made up of assumptions about rational economic behaviour developed by neo-classical economists. Understanding behavioural economics as a psychology of error allows me to shed light on the complicated relationship between behavioural economics and neo-classical economics. Specifically it helps explain how behavioural economists sought to strike a careful balance between critiquing the descriptive claims of neo-classical economists and reinforcing their normative ambitions.

A key question in behavioural finance is why prices in financial markets change. The field of behavioural finance evolved in an attempt to understand better and explain how cognitive errors and emotions influence investors' decision-making processes. Behavioural finance is the study of the psychological effects of market events on investors that affect finance decisions. It is not a new field of study, but more emphasis has been placed on this field of finance in the past two decades. Behavioural finance explores the irrational nature of investors' decisions. The primary objective of the research was to provide an understanding of the psychological impact of people on prices in financial markets. The secondary objectives are <ul> <li> to provide a brief history of behavioural finance;</li> <li> to show that there are alternatives to the efficient markets theory; and</li> <li> to demonstrate the impact of popular models on prices.</li></ul> The report was compiled based on a literature study on the topic of behavioural finance. The purpose of the literature study was to provide sufficient information to meet the objectives of the study as set out above. The following sources were used: <ul> <li> published articles;</li> <li> textbooks; and</li> <li> the Internet.</li> </ul> The efficient market hypothesis and the CAPM are challenged by behavioural finance. Prices of speculative assets do not always reflect fundamental values. The perceptions of investors play an important role in the determination of prices. Hence, when there are market crashes on the equities markets, the contagion effect amongst investors should not be underestimated. It is shown in this report that portfolio insurance is an important contributing factor to the magnitude of any crash on equities markets. Dividends are an important determinant for the fundamental value of shares. This contrasts with the revenue model that is used to value new economy shares, such as Internet companies. It is also clear that investors expect to receive a dividend. In this report, various theories strongly suggest investors' preference for dividends. These include the self-control and prospect theories, regret-aversion and the clientele effect. Changes in dividends affect share prices. A decrease in the dividend of a company is a clear signal to investors that the share price is overvalued. Movements in share prices are therefore at least partially the result of changes in dividends. Investment strategies that can be followed by investors include the following: <ul> <li> It may help to acquire closed-end fund shares at the listing of a new fund. The research shows that initially closed-end funds trade at a premium of up to ten per cent, but within 180 days, the premium evaporates and the fund starts to trade at a discount.</li> <li> The optimal strategy for sophisticated investors is a strategy that involves market timing with increased exposures to shares that have fallen, and decreased exposure to shares after they have risen in price.</li> <li> Individual investors should follow a buy-and-hold strategy, as opposed to a trading strategy, as the cost of trading is excessive.</li> <li> Arbitrageurs (professional investors) can earn higher than normal returns on markets that are excessively volatile. However, they need to be cautious, as they can also lose significant amounts of money when markets are volatile.</li> </ul> Careful consideration should be given to what shares to trade, as the cost of trading is expensive, as much as six per cent. Furthermore, it is important to have stop-loss limits in place and to sell shares once they breach the lower limit that has been set. The notion that losing shares in a portfolio will somehow turn into winning shares is, in most cases, incorrect. Copyright 2003, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Du Plessis, JJ 2003, Advances in behavioural finance, MBA dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-04202012-125738 / > F12/4/321/gm / Dissertation (MBA)--University of Pretoria, 2012. / Graduate School of Management / unrestricted