We investigate the effect of house money on individual investors. Our empirical evidence suggests that house money effect shows up in real-world financial markets, not just in artificial laboratory experiments. The results reveal a strong house money effect and show that investors tend to buy up trend stocks once they have experienced a prior gain. Only when a significant gain is being considered, does an individual become more inclined to take a risk. When the influence of a significant gain gradually depreciates over time, the greater tendency to take risk also diminishes. We find that individual investors exhibit the disposition effect— reluctant to realize losses and more willing to realize gains. They frequently realize small gains and less frequently take large losses, such a behavior may hurt their wealth because their gains are lower than their losses. Analyses of portfolio holdings reveal that individual investors hold relatively few different stocks and focus on a small number of stocks with which they are familiar. Their investment choice is driven by familiarity bias which diminishes the strength of the house money effect. When evaluate an investment gain, investors’ reference points adapt over time and the currently-salient reference point is the highest stock price attained some time ago.

Ce travail de thèse porte sur le choix, l’appréciation et la consommation des légumes chez les enfants de 8 à 11 ans en situation naturelle de repas scolaire. Dans une première étape, nous nous sommes focalisés sur les sujets (i.e. enfants) en étudiant leurs connaissances lexicales et perceptives des légumes. Ainsi, nous avons mis en évidence que la carotte, la tomate et la salade sont les trois légumes les plus familiers chez l’enfant. Les connaissances lexicales des légumes évoluent avec l’âge et sont plus importantes chez les enfants ruraux que chez les urbains. Nous n’avons pas observé de lien entre les connaissances perceptives des enfants et leur âge, leur genre, leur lieu de vie ou encore leur possession d’un potager à la maison. Deux objets ont été sélectionnés à l’issue de la première étape : un légume très connu et apprécié -la carotte ; un légume moins connu et moins apprécié -le brocoli. Dans une seconde étape, nous avons étudié l’influence de la forme et du temps de cuisson de ces deux légumes sur le comportement alimentaire des enfants. Les résultats indiquent que la carotte est plus choisie, appréciée et consommée sous une forme familière et peu cuite. Les enfants préfèrent visuellement les fleurettes de brocoli de petite taille aux fleurettes de grosse taille. Le temps de cuisson n’a pas modifié l’appréciation et la consommation des brocolis. La troisième étape a porté sur une variable situationnelle : les intitulés de plats. Nous avons, d’une part, analysé les préférences des enfants pour des intitulés de plats, et d’autre part, étudié l’influence de deux types d’intitulés sur le choix et la consommation de nouvelles recettes de carotte et de brocoli. L’ajout d’un intitulé de plat précisant le nom du légume s’est révélé être un moyen efficace pour augmenter la probabilité de choix d’une nouvelle recette de légumes présentée conjointement à une recette familière. L’intitulé n’a pas eu d’influence, lorsque la nouvelle recette a été présentée conjointement à une alternative plus appréciée (i.e. le riz). Ces travaux soulignent l’importance de la familiarité de l’enfant avec le légume et avec sa forme culinaire : les enfants choisissent, apprécient et consomment plus un légume familier et sous une forme culinaire familière. De plus, les résultats ont montré que l’intitulé du plat participe au choix des enfants et soulignent l’importance des facteurs situationnels dans le comportement alimentaire. / This PhD project aims at understanding better choice, liking and consumption of vegetables in 8- to -11-years children in natural situation of a school meal. In a first step, we focused on subjects (i.e. children) and studied their visual and perceptual knowledge of vegetables. We showed that carrots, tomatoes and lettuce were the three most familiar vegetables in children. Lexical knowledge of vegetables increases with age and is more important in rural children than urban ones. We did not observe a link between perceptual knowledge and children’s characteristics (i.e. age, gender, living environment or the possession of a vegetable garden at home). In a second step, we manipulated the shape and the duration of cooking for two objects (i.e. vegetables) selected at the end of the first step (i.e. a well-known and appreciated vegetable: carrots; a less known and less appreciated vegetable: broccoli). We studied the influence of these factors on children’s food behavior. Results showed that arrows are more frequently chosen, appreciated and consumed with a familiar shape and when less cooked. Visually, children preferred the broccoli presented in small florets rather than the big ones. The duration of cooking did not influence choices, liking and consumption of broccoli. The third step dealt with the influence of a situational variable: food labels. Firstly, we examined children’s preferences for several food labels, and secondly we studied the influence of these labels on children’s choice and consumption of two new recipes of carrots and broccoli. Adding a food label referring to the name of the vegetable was an effective mean to increase the probability that children would choose a new vegetable dish provided that no other more appreciated alternative was presented simultaneously. This research underlined the importance of children’s familiarity with the vegetable and its culinary form in their acceptance: children choose, appreciate and consume much more a familiar vegetable with a familiar culinary form. Also, the results showed that the food label participate to children food choice and underlined the importance of situational factors in food behavior.

Background: With social media being ever present in today's marketing world, research guiding and aiding this phenomenon is of mount importance. With social credibility and source attractiveness being lucrative schemes on citizen influencers persuasiveness towards target followers on Instagram and ultimately the drive of online purchase intentions, a holistic approach is introduced to understand each key determinant of each phenomena. Purpose: The purpose of this study is to investigate the determinants of citizens influencers’ persuasiveness and its relationship with source credibility and source attractiveness, as well as determining a consumers’ online purchase intention on the social media platform Instagram. Method: The study was written in a quantitative manner, aiding the need for generalizable data within the field. An exploratory research design was used with web-based surveys sent out to the sample selection for completion. Main Findings: Four out of the five hypothesis regarding source credibility and attractiveness towards the persuasiveness of citizen influencers were rejected, indicating interesting results as it contradicts previous literature. Furthermore, online purchase intention hypotheses were found to have more positive alignments towards citizen influencers. Grounds for theoretical and practical implications as well as future research endeavors were found.

De nombreux animaux évoluent dans un environnement social où les individus peuvent réaliser de l'écoute/observation clandestine, c'est-à-dire, obtenir des informations sur des compétiteurs ou partenaires sexuels potentiels en observant les interactions de leurs congénères. À l’inverse, les animaux engagés dans une interaction peuvent exprimer un effet d'audience: modifier leurs comportements en présence d’observateurs (audiences). Ce doctorat s'intéresse à la flexibilité et aux conséquences de ces comportements et recherche des stratégies individuelles dans leur utilisation chez le canari domestique. Les résultats indiquent que l'écoute clandestine influence les préférences sexuelles et l'investissement reproducteur des femelles. Ce dernier dépend également des statuts hiérarchiques et de la personnalité. Les effets d'audience sont mis en évidence chez les deux sexes et semblent complexes et flexibles. Leur expression dépend de la situation, du type d'audience, de la dominance et de la familiarité des individus impliqués mais pas de la personnalité. Ces résultats posent la question des bases cognitives impliquées dans l'écoute clandestine et les effets d'audience. / Many animals live in social environments where individuals can eavesdrop: get information on competitors or potential sexual partners by observing interactions between conspecifics. In such environments, interacting individuals might express an audience effect: they can change their behavior in the presence of eavesdroppers (i.e. an audience). This Ph.D. thesis focuses on the flexibility and the consequences of these behaviours and searches for individual strategies in their expression in domestic canaries. Results show that eavesdropping drives sexual preferences and reproductive effort in females. The latter is also influenced by dominance and personality. The existence of complex and flexible audience effects is demonstrated in males and females. Their expression depends on the situation, the type of audience, the dominance and familiarity of the interacting individuals but not on personality. Results raise the question of the cognitive foundations of eavesdropping and audience effects.

Inbreeding can have profound negative effects on individuals by reducing fertility and viability. In populations, inbreeding depression can reduce growth rates and increases extinction risk. The aims of this thesis are to investigate inbreeding depression in male guppies (Poecilia reticulata) and to study the evolution of mechanisms for inbreeding avoidance in females, using guppies from a feral population in Queensland, Australia. Male guppies are highly polymorphic in their sexual ornamentation, indeed they show one of the most extreme polymorphisms observed in nature. Female guppies exhibit complex mate choice based on preferences for ornamentation, as well as social context. I aim is to examine how these factors of inbreeding avoidance alter sexual selection. In male guppies I found strong inbreeding depression in male sperm numbers, which is amplified under semi-natural compared to laboratory conditions (Chapter 2). Moreover, inbreeding depression results in low fertility under sperm competition: an experiment using artificial insemination techniques reveals that highly inbred males are heavily disadvantaged in gaining paternity (Chapter 3). On population level, inbreeding depression is manifest in reduced growth rates, predominantly in the early stages of inbreeding (Chapter 4). Population growth at inbreeding coefficients f=0.375-0.59 did not seem to lead to inbreeding depression, whereas lower levels of inbreeding reduced population growth. Although the growth rates in inbred populations appear normal, severe inbreeding depression is uncovered after outbred immigrants are added. Specifically, male immigrants are most efficient in short-term genetic rescue, probably due to insemination of large numbers of females whereas females are limited in the number of eggs they can produce (Chapter 4). Male ornamental traits show significant inbreeding depression in semi-natural conditions only (Chapters 2 & 3). Inbreeding avoidance mechanisms seem to have evolved in females: they prefer courtship displays of non-inbred males (Chapter 2), unfamiliar males (Chapter 5) and males with rare patterns (Chapter 6). This preference might increase the mating success of immigrants, and may have evolved to facilitate the avoidance of inbreeding. Together with context-independent preferences for ornament combinations (Chapter 6), it also offers an explanation for the maintenance of polymorphism in this species.

Inbreeding can have profound negative effects on individuals by reducing fertility and viability. In populations, inbreeding depression can reduce growth rates and increases extinction risk. The aims of this thesis are to investigate inbreeding depression in male guppies (Poecilia reticulata) and to study the evolution of mechanisms for inbreeding avoidance in females, using guppies from a feral population in Queensland, Australia. Male guppies are highly polymorphic in their sexual ornamentation, indeed they show one of the most extreme polymorphisms observed in nature. Female guppies exhibit complex mate choice based on preferences for ornamentation, as well as social context. I aim is to examine how these factors of inbreeding avoidance alter sexual selection. In male guppies I found strong inbreeding depression in male sperm numbers, which is amplified under semi-natural compared to laboratory conditions (Chapter 2). Moreover, inbreeding depression results in low fertility under sperm competition: an experiment using artificial insemination techniques reveals that highly inbred males are heavily disadvantaged in gaining paternity (Chapter 3). On population level, inbreeding depression is manifest in reduced growth rates, predominantly in the early stages of inbreeding (Chapter 4). Population growth at inbreeding coefficients f=0.375-0.59 did not seem to lead to inbreeding depression, whereas lower levels of inbreeding reduced population growth. Although the growth rates in inbred populations appear normal, severe inbreeding depression is uncovered after outbred immigrants are added. Specifically, male immigrants are most efficient in short-term genetic rescue, probably due to insemination of large numbers of females whereas females are limited in the number of eggs they can produce (Chapter 4). Male ornamental traits show significant inbreeding depression in semi-natural conditions only (Chapters 2 & 3). Inbreeding avoidance mechanisms seem to have evolved in females: they prefer courtship displays of non-inbred males (Chapter 2), unfamiliar males (Chapter 5) and males with rare patterns (Chapter 6). This preference might increase the mating success of immigrants, and may have evolved to facilitate the avoidance of inbreeding. Together with context-independent preferences for ornament combinations (Chapter 6), it also offers an explanation for the maintenance of polymorphism in this species.

Ciascuno di noi, posto davanti a un'opera d'arte è in grado di esprimere una preferenza, anche se non l'ha mai vista prima. Child (1965) sosteneva come in questo processo di valutazione fosse determinante il ruolo giocato dalla personalità, tuttavia l'autore aggiungeva anche che la conoscenza o l'esperienza in campo artistico potrebbero ridurre se non annullare questo effetto. Furham e Walker (2001) hanno invece sottolineato come la personalità potrebbe essere maggiormente legata allo sviluppo della familiarità artistica invece che determinare direttamente le preferenze pittoriche. Il presente lavoro si pone dunque l'obiettivo di studiare la familiarità artistica in veste di mediatore tra le variabili di personalità e le preferenze pittoriche. I risultati mettono in luce come questa mediazione avviene per la ricerca di brivido e avventura, il bisogno di chiusura cognitiva e la sensibilità estetica (fattori di bellezza classica e rapimento estatico). Sempre attraverso questi modelli di mediazione, le preferenze pittoriche sono state analizzate considerando le principali caratteristiche dello stimolo: lo stile pittorico, il soggetto rappresentato e il livello di complessità. in particolare lo stile e il soggetto hanno messo in luce interessanti differenze. Si auspicano futuri studi che tengano conto degli effetti di interazione sia tra le variabili di personalità, sia tra le caratteristiche delle opere pittoriche. / Everyone could say if he likes or not a work of art, even if he never saw it before. Child (1965) stressed the importance of the personality traits for this process of evaluation, however he also suggested that personality variables become less important as knowledge of art increases. Furham e Walker (2001) proposed that personality variables predict exposure to art (galleries visited, art purchased, art studied) which in part predicts familiarity which is the most direct predictor of art preferences. The aim of this study is testing the role of artistic familiarity as mediator between personality traits (predictors) and pictorial preferences (outcome). Results show mediation for thrill and adventure seeking, need for cognitive closure and aesthetic sensitivity. Pictorial preferences are also studied in mediation models considering the characteristics of the works of art: style, represented subject and simplicity/complexity. In particular, the style and the represented subject show significant differences. Future research is needed, particularly on the study of the interaction between both personality variables and pictorial characteristics.

This dissertation aims to explore the nature of early social preferences by testing attention to a cue that might have evolved as a reliable signal of shared group membership – shared cultural knowledge. Part 1 shows that children attend to this cue when making social choices: Children both prefer others who know songs they themselves know, and avoid others who know songs they do not know, while other cues such as shared preferences for songs are not as powerful drivers of social preferences. Part 2 shows that this cue affects how five-months-old infants allocate attention to human singers. After listening to two individuals singing different songs, infants look longer at singers of familiar songs than at singers of unfamiliar songs. When both songs are unfamiliar, infants do not show preferences for singers of songs that follow or violate Western melodic structure, although they are sensitive to these differences. In focusing on familiar songs but not musical styles, infants may selectively attend to information that might mark group membership later in life, namely shared knowledge of specific songs. Part 3 investigates whether children are selective in the properties they use to infer that two individuals belong to the same group, targeting two potentially important social cues: race and gender. Specifically, Part 3 asks if children attribute shared musical knowledge to individuals of the same race or gender. Four-year-olds attribute shared knowledge to individuals of the same gender, but not of the same race. Five-year-olds attribute shared knowledge to individuals of the same race, but not of the same gender. In contrast, a control unrelated to group-membership – attributions of shared musical preferences – do not yield any dissociation between attributions based on race or gender. Thus, as they gain experience, children seem to adaptively update the social cues they use to infer shared group-membership. Together these results begin to elucidate the mechanisms underlying early social preferences by showing that children might selectively attend to the most reliable cues to shared group-membership, which, in turn, might allow them later in life to participate in the complex social organization that is unique to human societies. / Psychology

Cognitive Event-Related Potential (ERP) recordings have been used to study the neurophysiological correlates of recognition memory. Previous ERP research has demonstrated that on tasks of recognition memory, Old items elicit ERP responses that are more positive in electrical amplitude than the ERP responses elicited by New items, commonly referred to as ERP Old/New positivity effects. ERP Old/New positivity effects have been used to make inferences about cognitive processes mediating recognition memory, such as the early frontal Old/New positivity effect that has been associated with familiarity and the late parietal Old/New positivity effect that has been associated with recollection. These effects have been demonstrated different types of stimuli and on different types of recognition memory tasks. However, a systematic comparison of ERP Old/New positivity effects across different recognition memory tasks is lacking, particularly with respect to Remote Long-term memory. This thesis asked how ERP Old/New positivity effects differ between tasks of Short-term, Recent Long-term, and Remote Long-term memory tasks for faces. Experiment 1 simulated the condition of limited overt communication skills by analyzing the brain responses to memory stimuli, regardless of the overt behavioural response from healthy, “honest” participants. Experiment 2 examined the ERP responses of healthy participants instructed to feign a memory impairment. ERP Old/New positivity effects similar to those described in the experimental ERP literature were observed on the Short-term and Remote Long-term memory tasks in both Experiments 1 and 2. However, response accuracy was lower than expected on the Recent Long-term task resulting in weak ERP results. A comparison of the ERP Old/New responses between the Honest Response (Experiment 1) and the Simulated Memory Malingering (Experiment 2) groups found that despite differing overt behavioural responses, the ERP Old/New responses remained similar. The results demonstrate a similar electrophysiological mechanism mediating Short-term, Recent Long-term, and Remote Long-term recognition memory ERP responses, despite the different neuroanatomical substrates that have been proposed these different types of memory. Although an improved measure of Recent Long-term memory is needed, the results of this thesis are promising and demonstrate that ERP recordings could provide an objective instrument for measuring recognition memory functioning in clinical settings.

Inbreeding can have profound negative effects on individuals by reducing fertility and viability. In populations, inbreeding depression can reduce growth rates and increases extinction risk. The aims of this thesis are to investigate inbreeding depression in male guppies (Poecilia reticulata) and to study the evolution of mechanisms for inbreeding avoidance in females, using guppies from a feral population in Queensland, Australia. Male guppies are highly polymorphic in their sexual ornamentation, indeed they show one of the most extreme polymorphisms observed in nature. Female guppies exhibit complex mate choice based on preferences for ornamentation, as well as social context. I aim is to examine how these factors of inbreeding avoidance alter sexual selection. In male guppies I found strong inbreeding depression in male sperm numbers, which is amplified under semi-natural compared to laboratory conditions (Chapter 2). Moreover, inbreeding depression results in low fertility under sperm competition: an experiment using artificial insemination techniques reveals that highly inbred males are heavily disadvantaged in gaining paternity (Chapter 3). On population level, inbreeding depression is manifest in reduced growth rates, predominantly in the early stages of inbreeding (Chapter 4). Population growth at inbreeding coefficients f=0.375-0.59 did not seem to lead to inbreeding depression, whereas lower levels of inbreeding reduced population growth. Although the growth rates in inbred populations appear normal, severe inbreeding depression is uncovered after outbred immigrants are added. Specifically, male immigrants are most efficient in short-term genetic rescue, probably due to insemination of large numbers of females whereas females are limited in the number of eggs they can produce (Chapter 4). Male ornamental traits show significant inbreeding depression in semi-natural conditions only (Chapters 2 & 3). Inbreeding avoidance mechanisms seem to have evolved in females: they prefer courtship displays of non-inbred males (Chapter 2), unfamiliar males (Chapter 5) and males with rare patterns (Chapter 6). This preference might increase the mating success of immigrants, and may have evolved to facilitate the avoidance of inbreeding. Together with context-independent preferences for ornament combinations (Chapter 6), it also offers an explanation for the maintenance of polymorphism in this species.