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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Learning and loss aversion : evidence from a financial betting market

Ó Briain, Tomás January 2016 (has links)
This research is motivated by a number of open questions in the behavioural finance literature. Firstly, if investors do not learn in a rational Bayesian manner but rather suffer from biases set out in the naïve reinforcement hypothesis, rationality assumptions in individual preference models may not hold. I use a unique longitudinal dataset comprising in excess of 1.5 million fixed-odds financial bets, where bettors perform identical, consecutive decisions which mimic financial choices made in a laboratory, but the use of their own funds departs from the artificiality of an experiment. I present evidence of unwarranted overconfidence generated by reinforcement learning in both real and simulated markets. Secondly, Kahneman and Tversky (1979) state that losses loom larger than gains. I examine whether the disposition to avoid losses is driving behaviour in the losing domain in the dataset and conclude that there is little evidence of loss aversion. I differentiate between betting on Financial Markets, in which agents may perceive an internal locus of control, and betting on the simulated market, where results are uncorrelated and in which the emotions of regret and disappointment may not loom as large. Finally, Odean (1998) provides evidence that investors readily realise paper gains by selling their winning stocks, yet hold on to their losing stocks too long. This loss aversion is consistent with Kahneman and Tversky (1979) prospect theory, however, how long would the investor hold on to a stock that is losing value on a day-to-day basis? Conversely, would an investor rush to sell a stock that has yielded positive returns in each month during the past year? I test the interaction between learning and loss aversion in a financial betting experiment in which two treatment groups are subjected to consecutive gains or losses.
122

Inter- and Intra-sensory Modality Stimulus Scaling: A Method for the Determination of the Relative Salience of Stimuli in Poison-based Aversion Learning by Pigeons

Pounds, David L. 01 May 1981 (has links)
One of the most rapidly expanding areas of research in psychology has been poison-based aversion learning (PBAL). The PBAL paradigm typically involves: exposing an animal to a novel substance; inducing illness following ingestion of that substance; and then providing access to the substance at a later time. The initial reaction to the novel substance is generally to reduce consumption, a finding labeled neophobia. The reduction of substance intake on test day is called learned aversion. Following demonstrations of cue-to-consequence specificity (i.e., the differential associability of some stimuli with certain consequences) in PBAL research with rats, recent research has focused on PBAL by avians. Such research has been instigated by speculation that avians might be specially adapted to better associate visual rather than flavor stimuli with illness. Studies to determine the relative salience of visual or flavor cues in avian PBAL have reported contradictory findings. A number of methodological differences exist between these studies including differences in stimulus intensity and type, duration between conditioning and assessment, and method of assessment. The current series of experiments made several methodological improvements to clarify the issue of cue to consequence specificity in PBAL with avians. Three experiments with pigeons as subjects are reported. The first experiment equated (scaled) stimulus intensity across different sense modalities by equating neophobic responses to various concentrations of salt, sour, and red water. The second experiment determined the extended effects of the illness-inducing stimulus alone on fluid consumption by pigeons in a restricted access to water environment. The third experiment was based upon results from the first two experiments and assessed aversion, at two different post-injection times, to one of two concentrations of either salt, sour, or red water CSs. In addition, a compound (flavor plus color) conditioning group was employed. Aversion was a function of flavor or color stimulus intensity. No differences were observed in degree of aversion demonstrated by groups receiving stimuli equated for initial suppression. Evidence for overshadowing or potentiation was not found. The results support the position that neither flavor or color stimuli are necessarily the most salient in avian PBAL.
123

ADHD Through the Lens of Game Design : How Digital RPGs Neutralize the Symptoms of Inattention Amongst Swedish Adults with ADHD

Ströberg, Simon January 2018 (has links)
ADHD (Attention Deficit Hyperactivity Disorder) is a commonly diagnosed mental disorder with an estimated global prevalence of 5.29% that exhibit inattentive, hyperactive and impulsive behaviors, many of which can negatively impact an individual’s social, academic, occupational and everyday-life. Studies based on the Delay Aversion Hypothesis have shown that video-games effectively contribute to the neutralization of some of the inattentive symptoms of ADHD, and that games could act as a possible treatment option for individuals with ADHD. Attempts to use video games as a treatment option has previously been tried, however to a limited extent. This study approaches the topic from the game design perspective, and discusses which game mechanics, activities and stimuli contribute to the possible neutralization of the inattentive symptoms of ADHD, in order to lay a foundation for future research within the area. The study found that the participants with ADHD acted in ways that contradicted some of the described symptoms of ADHD in the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders) when playing video games, which could be attributed to the amount of stimuli available in video games. Additionally, the participants’ level of motivation when playing video games seemed to be strongly correlated to the principles of andragogy, which could indicate that children with ADHD might benefit from an educational system that combines and incorporates principles from both andragogy and pedagogy.
124

Investigating Methods to Reduce Black Bear (Ursus americanus) Visitation to Anthropogenic Food Sources: Conditioned Taste Aversion and Food Removal

Signor, Kari D. 01 December 2009 (has links)
Conflicts between humans and black bears (Ursus americanus) jeopardize the safety of both humans and bears, especially when bears become food-conditioned to anthropogenic food sources in areas such as campgrounds. Interest in using non-lethal techniques, such as aversive conditioning, to manage such conflicts is growing. I conducted a captive experiment at The Wildlife Science Center in Minnesota and two field experiments in the La Sal Mountains, Utah, to investigate the effects of taste aversion conditioning using thiabendazole (TBZ) with a novel flavor cue and food removal on black bear food consumption and visitation to human food sources. In 2007, I conducted food trials with 6 captive black bears (3 control, 3 treatment). Controls received 1 kg baked goods scented with a peppermint-canola oil mixture and treatments received 1 kg baked goods also scented with a peppermint-canola oil mixture but mixed with 10-20 g TBZ. In the 2007 field experiment, I baited 24 field sites with 300 g of baked goods during a baseline phase for approximately 3 weeks. Half of these sites were then treated with 10 g of TBZ and camphor during a treatment phase for 4 weeks. In 2008, I baited 22 sites with 300 g of baked goods during a baseline phase for approximately 4 weeks. I then removed food and discontinued baiting at half of the sites for 4 weeks. Infrared cameras and barbed-wire hair snags were established at field sites to document bear visitation. I did not establish taste aversion in treated bears in captivity and bears fully consumed food in the majority of trials. Treating food supplies with 10 g TBZ and camphor flavor did not significantly reduce bear visitation (P = 0.615) or food consumption at field sites (P = 0.58). However, I observed a significant reduction in bear activity at sites where food was removed (P = 0.006). Potential reasons for my failure to reduce bear visitation using thiabendazole include insufficient conditioning, reluctance of bears to desist in investigating sites that previously contained untreated food, and masking of a treatment effect due to continued encounters of sites by new individuals.
125

Bait Shyness and Neophobia in Several Species of Osteichthyes: An Extension of Taste Aversion Studies to the Superclass Pices

Roberts, Brent W. 01 May 1978 (has links)
Three experiments were conducted with five species of tropical fish to investigate the phenomena of taste aversion and food neophobia. In addition, an experiment determined specifically if position in the tank could acquire conditioned aversive properties. In Experiment 1 , four habituated fish were fed novel meat-flavored pellets on the treatment day. Six were made ill within 30, 60, or 90 minutes (2 subjects each) by intragastric administration of syrup or Epicac. The following day all were fed familiar commercial pellets. On the second day after treatment, all were offered the meat-flavored pellets. Results showed longer latencies, more tasting, and decreased consumption of novel pellets. All measures differed significantly for the treatment subjects compared to their own baseline and controls. Experiment II demonstrated food neophobia in four in experienced fish. After habituation they were fed novel meat-flavored pellets but not made ill (day 0). On day 1 and 2 they received familiar diet and were made ill after the feeding on day 2. On day 3 they received familiar food again and no change in approach latency, testing response, or quantity consumed occurred. On day 4, they were offered the novel meat-flavored pellets which they refused. These results indicate that the fish associated the illness with the more "novel" food even though their familiar diet was temporally closer to the illness. In Experiment III five species of naive fish were habituated to 20-gallon tanks and made ill after eating in one end and not in the other. The same food was us ed in both ends. The "illness end" could have taken on discriminitive properties and food consumption there should have decreased, as opposed to the other "safe end". The results indicated that "place" did not acquire aversive discriminitive properties. Food consumption decreased in quantity, food approach latencies increased and length of tasting bouts increased in both ends. These experiments were the first to use these species of fish in this type of research. The results extend the phenomena of taste aversion and food neophobia. In addition, Experiment III systematically replicated the hypothesis of relevant relations between stimuli and showed that it is easier to learn certain consequences with certain cues than with others. In this case illness was quickly associated with taste but "place" was treated as irrelevant.
126

Conexôes aferentes e eferentes do núcleo interpeduncular com enfoque especial para os circuitos entre a habênula, o núcleo interpeduncular e os núcleos da rafe. / Afferent and efferent connections of the interpeduncular nucleus, with special reference to the circuits linking the habenula, interpeduncular nucleus, and raphe nuclei.

Bueno, Débora Nunes Martins 22 October 2018 (has links)
A habênula é uma estrutura epitalâmica diferenciada em dois complexos nucleares, a habênula medial (MHb) e a habênula lateral (LHb). Recentemente, a MHb junto com seu alvo principal, o núcleo interpeduncular (IP), foram identificados como estruturas chaves envolvidas na mediação dos efeitos aversivos da nicotina. Contudo, estruturas intimamente interligadas com o eixo MHb-IP, como o núcleo mediano (MnR), a parte caudal do núcleo dorsal da rafe (DRC), e o núcleo tegmental laterodorsal (LDTg) podem contribuir para os efeitos comportamentais da nicotina. As conexões aferentes e eferentes do IP, até agora, não foram sistematicamente investigadas com traçadores sensíveis. Assim, realizamos injeções de traçadores retrógrados ou anterógrados em diferentes subdivisões do IP, no MnR, ou LDTg e também examinamos a assinatura neuroquímica de algumas das mais proeminentes aferências dessas três estruturas através da combinação de rastreamento retrógrada com métodos de imunofluorescência e hibridização in situ. Além de receber entradas topograficamente organizadas da MHb e também da LHb, observamos que o IP está principalmente interligado de forma recíproca com estruturas da linha média, incluindo o MnR/DRC, o núcleo incerto, o núcleo supramamilar, o septo e o LDTg. As conexões bidirecionais entre o IP e o MnR assim como as entradas do LDTg para o IP provaram de ser principalmente GABAérgicas. Com respeito a uma possível topografia das saídas do IP, todos os subnúcleos do IP deram origem a projeções descendentes, enquanto as suas projeções ascendentes, incluindo projeções focais para o hipocampo ventral, o septo ventrolateral, e a LHb originaram da região dorsocaudal do IP. Nossos resultados indicam que o IP está intimamente associado a uma rede de estruturas da linha média, todos eles considerados moduladores chave da atividade teta do hipocampo. Assim, o IP forma um elo que liga MHb e LHb com esta rede e com o hipocampo. Além disso, as proeminentes interconexões predominantemente GABAérgicas entre IP e MnR, assim como IP e LDTg, suportam um papel chave dessas vias bidirecionais na resposta comportamental à nicotina. / The habenula is an epithalamic structure differentiated into two nuclear complexes, medial (MHb) and lateral habenula (LHb). Recently, MHb together with its primary target, the interpeduncular nucleus (IP), have been identified as major players in mediating the aversive effects of nicotine. However, structures downstream of the MHb-IP axis, including the median (MnR), caudal dorsal raphe nucleus (DRC), and the laterodorsal tegmental nucleus (LDTg), may contribute to the behavioral effects of nicotine. The afferent and efferent connections of the IP have hitherto not been systematically investigated with sensitive tracers. Thus, we placed injections of retrograde or anterograde tracers into different IP subdivisions, the MnR, or LDTg and additionally examined the transmitter phenotype of some major IP and MnR afferents by combining retrograde tract tracing with immunofluorescence and in situ hybridization techniques. Besides receiving topographically organized inputs from MHb and also LHb, we found that the main theme of IP connectivity are strong reciprocal interconnections with midline structures, including the MnR/DRC, nucleus incertus, supramammillary nucleus, septum, and LDTg. The bidirectional connections between IP and MnR and the LDTg inputs to the IP proved to be mostly GABAergic. Regarding a possible topography of IP outputs, all IP subnuclei gave rise to descending projections, whereas ascending projections, including focal projections to the ventral hippocampus, ventrolateral septum, and LHb mostly originated from the dorsocaudal IP. Our findings indicate that IP is closely associated to a distributed network of midline structures, all of them considered key modulators of hippocampal theta activity. Thus, IP forms a node that links MHb and LHb with this network and the hippocampus. Moreover, the rich predominantly GABAergic interconnections between IP and MnR, as well as IP and LDTg, support a cardinal role of these bidirectional pathways in the behavioral response to nicotine.
127

Dynamique de la mémoire au cours du développement post-natal, étude chez le raton

Languille, Solène 01 October 2009 (has links) (PDF)
Les deux aspects essentiels de la mémoire sont la formation de la trace et la rétention du souvenir à long terme. Afin de comprendre ces processus, nous avons étudié leur mise en place au cours de l'ontogenèse. Chez le raton, nous avons montré que : 1) ERK1/2 et la synthèse de nouvelles protéines sont nécessaires à la consolidation et reconsolidation dès 3 jours postnatals ; 2) les cinétiques de stabilisation de la mémoire raccourcissent au cours du développement post-natal ; 3) une mémoire précoce peut s'inverser avec l'âge ; 4) la capacité de rétention à très long terme apparaît pendant une période critique (une semaine avant le sevrage). Il semble donc que la mémoire précoce implique des mécanismes moléculaires similaires à ceux observés chez l'adulte, mais sa dynamique évolue au cours du développement post-natal.
128

Modèles DSGE Nouveaux Keynésiens, Monnaie et Aversion au Risque.

Benchimol, Jonathan 09 December 2011 (has links) (PDF)
Cette thèse présente trois modèles théoriques et empiriques de la Zone Euro, mettant en perspective l'influence de l'aversion au risque et de la monnaie sur différentes variables. Ces modèles d'équilibre général intertemporels et stochastiques (DSGE) s'inscrivent dans le cadre de la théorie des Nouveaux Keynésiens. Dans un premier modèle de base, nous montrons que l'aversion au risque influence la production, contribuant à sa baisse, notamment en période de crise. Pendant ces périodes de crise (Système Monétaire Européen, 1992; Internet, 2000; Subprimes, 2007), l'aversion au risque impacte significativement la détention de monnaie réelle. Dans un second modèle, dans lequel la monnaie est considérée comme un facteur de production, cette dernière n'a pas d'implication significative sur les dynamiques des autres variables. L'hypothèse de rendements d'échelle constants est par là même rejetée. Dans un troisième modèle, en utilisant une fonction d'utilité non-séparable entre la consommation et les encaisses réelles, nous montrons que le rôle de ces dernières sur la production dépend du degré d'aversion au risque des agents, devenant significatif lorsque celui-ci est deux fois plus élevé que la normale. Enfin, nous testons et comparons ce modèle avec le modèle de base pendant les trois périodes susmentionnées. La monnaie explique alors une partie significative des variations de la production pendant ces crises. De plus, notre analyse montre qu'un modèle non-séparable entre la consommation et les encaisses réelles a de meilleures capacités prédictives qu'un modèle séparable en période de crise.
129

Essays on Public Macroeconomic Policy

Prado, Jr., Jose Mauricio January 2007 (has links)
<p>The thesis consists of three self-contained essays on public policy in the macroeconomy.</p><p>“Government Policy in the Formal and Informal Sectors” quantitatively investigates the interaction between the firms' choice to operate in the formal or the informal sector and government policy on taxation and enforcement. Taxes, enforcement, and regulation are incorporated in a general equilibrium model of firms differing in their productivities. The model quantitatively accounts for the keys aspects in the data and allows me to back out country-specific enforcement levels. Some policy reforms are analyzed and the welfare gains can be fairly large.</p><p>“Determinants of Capital Intensive and R&D Intensive Foreign Direct Investment” studies the determinants of capital intensity and technology content of FDI. Using industry data on U.S. FDI abroad and data on many different host countries' institutional characteristics, we show that there is a differential response of FDI flows to investment climate according to the capital intensity of the industries receiving the investments. We find that better protection of property rights has a significant positive effect on R&D intensive capital flows. We find evidence that an increase in workers' bargaining power results in a reduction of both kinds of FDI. </p><p>“Ambiguity Aversion, the Equity Premium, and the Welfare Costs of Business Cycles” examines the relevance of consumers’ ambiguity aversion for asset prices and how consumption fluctuations influence consumer welfare. First, in a Mehra-Prescott-style endowment economy, we calibrate ambiguity aversion so that asset prices are consistent with data: a high return on equity and a low return on risk-free bonds. We then use this calibration to investigate how much consumers would be willing to pay to reduce endowment fluctuations to zero, thus delivering a Lucas-style welfare cost of fluctuations. These costs turn out to be very large: consumers are willing to pay over 10% of consumption in permanent terms.</p>
130

Förlustspiralen : En studie av riskbeteende i spelet Black Jack.

Marklund, Victor, Öhman, Mattias January 2010 (has links)
<p>Den traditionella förväntade nyttoteorin har kritiserats för att inte vara realistisk i sina förutsägelser om hur beslut tas vid risk. Eftersom de flesta situationer innefattar någon form av risk är det viktigt att utreda ifall man bör söka efter en alternativ teori. I denna uppsats undersöks hur väl nyttoteorin och en konkurrent till denna, prospektteorin, kan förklara riskbeteendet hos Black Jack-spelare. Detta görs genom en studie av fem individers spelbeteende på en krog i centrala Jönköping. Materialet analyseras både grafiskt och statistiskt genom att undersöka om individernas beteende förändras beroende på utfallet dels i de fem senaste händerna och dels under hela spelomgången. Resultaten tyder på att individer tar bättre beslut om de har en ackumulerad vinst och sämre beslut om de har en ackumulerad förlust under den tidigare spelomgången, vilket är förenligt med prospektteorin. Samtidigt upptäcks en uttröttningseffekt som leder till sämre beslut tagna ju längre man har spelat, som ingen av teorierna förutsäger. En spelare som har en vinst kan kompensera för denna effekt, men en spelare med förlust kommer att ta sämre beslut både på grund av förlusten och på grund av uttröttning i något som kan kallas för en förlustspiral.</p>

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