Exploring social metacognition

This thesis explores two questions: does the way individuals seek advice produce echo chamber-like networks; and is the well-established phenomenon of egocentric discounting explicable as a rational process? Both parts are presented within a framework of advice as information transfer; the implications for wider interpretations of advice are discussed in the conclusion. Both parts are investigated with a mixture of computational simulations and behavioural experiments. For the first question, behavioural experiments implementing a Judge-Advisor System with a perceptual decision-making task and a date estimation task are used to characterise people’s propensity to use agreement as a signal of advice quality in the absence of feedback. These experiments provide moderate evidence suggesting that people do do this, and that experience of agreement in the absence of feedback increases their trust in advisors. Agent-based computational simulations take the results of the behavioural experiments and simulate their effects on trust ratings between agents. The simulations indicate that including the kind of heterogeneity seen in the participants in the behavioural experiments slows down the formation of echo chambers and limits the extent of polarisation. In the second part, I argue that egocentric discounting deviates from a normative model of advice-taking because it is a rational response to concerns that always accompany advice: that the advice might be deliberately misleading, lazily researched, or misunderstood. Evolutionary computational simulations of advice-taking illustrate that when any of these circumstances might be true, egocentric discounting emerges as an adaptive response. Behavioural experiments using a date estimation task within a Judge-Advisor System test whether people respond adaptively to alterations in the circumstances explored in the evolutionary simulations. These experiments show that people respond flexibly to changes in the probability that their advisor will attempt to mislead them. Experiments attempting to explore people’s ability to flexibly respond to acquiring information about an advisor’s confidence calibration were inconclusive. A web-book version of this thesis is available at https://mjaquiery.github.io/oxforddown/. Its RMarkdown source code is available at https://github.com/mjaquiery/oxforddown

Preferences for advisor agreement and accuracy

Previous research has shown that people are more influenced by advisors who are objectively more accurate, but also by advisors who tend to agree with their own initial opinions. The present experiments extend these ideas to consider people’s choices of who they receive advice from—the process of source selection. Across a series of nine experiments, participants were first exposed to advisors who differed in objective accuracy, the likelihood of agreeing with the participants’ judgments, or both, and then were given choice over who would advise them across a series of decisions. Participants saw these advisors in the context of perceptual decision and general knowledge tasks, sometimes with feedback provided and sometimes without. We found evidence that people can discern accurate from inaccurate advice even in the absence of feedback, but that without feedback they are biased to select advisors who tend to agree with them. When choosing between advisors who are accurate vs. likely to agree with them, participants overwhelmingly choose accurate advisors when feedback is available, but show wide individual differences in preference when feedback is absent. These findings extend previous studies of advice influence to characterise patterns of advisor choice, with implications for how people select information sources and learn accordingly

Stage 1 Registered Report: How responsibility attributions to self and others relate to outcome ownership in group decisions [version 2; peer review: 2 approved]

Responsibility judgements have important consequences in human society. Previous research focused on how someone's responsibility determines the outcome they deserve, for example, whether they are rewarded or punished. Here, we investigate the opposite link: How outcome ownership influences responsibility attributions in a social context. Participants in a group of three perform a majority vote decision-making task between gambles that can lead to a reward or no reward. Only one group member receives the outcome and participants evaluate their and the other players' responsibility for the obtained outcome. Two hypotheses are tested: 1) Whether outcome ownership increases responsibility attributions even when the control over an outcome is similar. 2) Whether people's tendency to attribute higher responsibility for positive vs negative outcomes will be stronger for players who received the outcome. The findings of this study may help reveal how credit attributions can be biased toward particular individuals who receive outcomes as a result of collective work

Defining properties of neural crest-derived progenitor cells from the apex of human developing tooth

The connective tissue of the human tooth arises from cells that are derived from the cranial neural crest and, thus, are termed as "ectomesenchymal cells." Here, cells being located in a pad-like tissue adjacent to the apex of the developing tooth, which we designated the third molar pad, were separated by the microexplant technique. When outgrowing from the explant, dental neural crest-derived progenitor cells (dNC-PCs) adhered to plastic, proliferated steadily, and displayed a fibroblast-like morphology. At the mRNA level, dNC-PCs expressed neural crest marker genes like Sox9, Snail1, Snail2, Twist1, Msx2, and Dlx6. Cytofluorometric analysis indicated that cells were positive for CD49d (alpha4 integrin), CD56 (NCAM), and PDGFRalpha, while negative for CD31, CD34, CD45, and STRO-1. dNC-PCs could be differentiated into neurogenic, chondrogenic, and osteogenic lineages and were shown to produce bone matrix in athymic mice. These results demonstrate that human third molar pad possesses neural crest-derived cells that represent multipotent stem/progenitor cells. As a rather large amount of dNC-PCs could be obtained from each single third molar, cells may be used to regenerate a wide range of tissues within the craniofacial region of humans

Stage 1 Registered Report: How responsibility attributions to self and others relate to outcome ownership in group decisions [version 1; peer review: 1 approved with reservations]

Responsibility judgements have important consequences in human society. Previous research focused on how someone's responsibility determines the outcome they deserve, for example, whether they are rewarded or punished. Here, we investigate the opposite link: How outcome ownership influences responsibility attributions in a social context. Participants in a group of three perform a majority vote decision-making task between gambles that can lead to a reward or no reward. Only one group member receives the outcome and participants evaluate their and the other players' responsibility for the obtained outcome. Two hypotheses are tested: 1) Whether outcome ownership increases responsibility attributions even when the control over an outcome is similar. 2) Whether people's tendency to attribute higher responsibility for positive vs negative outcomes will be stronger for players who received the outcome. The findings of this study may help reveal how credit attributions can be biased toward particular individuals who receive outcomes as a result of collective work

Esthétique de l’entremêlement dans les portraits du jeune Lancelot et de Claudas de la Terre Déserte dans le Lancelot en prose

Les modèles préconisés par les arts poétiques pour la description des personnes laissent à ceux qui se livrent à l’exercice du portrait la possibilité de renouveler le modèle théorique. Cette étude propose une analyse des portraits, en regard l’un de l’autre, du jeune Lancelot et de Claudas de la Terre Déserte tels qu’ils apparaissent dans le Lancelot en prose. Le rédacteur de ce roman développe les portraits autour des notions d’« entremêlement » des composantes des deux personnages et de « mesure » dans leurs proportions. Si la mesure est d’ordinaire source d’harmonie, le traitement réservé à ces deux personnages prouve plutôt le contraire. Quant à l’« entremêlement », il présente un résultat différent selon que l’on considère Claudas ou Lancelot. Le premier reste ambivalent, double, tandis que le second dépasse les éléments contradictoires qui le composent en les intégrant : ces derniers fusionnent en se valorisant mutuellement.The poetic arts have recommended models for describing characters. However, these models are not fixed and allow anyone who wishes to portray a character to renew them. This study offers a comparative portrait analysis of the young Lancelot and Claudas de la Terre Déserte as they appear in Lancelot en prose. The author of this novel develops the portraits through notions of entremêlement [entanglement] of the components of the two characters and of mesure [measure] of their proportions. If measure is usually a source of harmony, the manner of describing the two characters proves rather the opposite. The results differ for Claudas or Lancelot when entremêlement [entanglement] is considered. The former is ambivalent, double, whilst the latter transcends the contradictory elements that compose him by integrating them. Their merger increases the value of each another

Three-dimensional perfusion culture of human adipose tissue-derived endothelial and osteoblastic progenitors generates osteogenic constructs with intrinsic vascularization capacity

In this study, we aimed at generating osteogenic and vasculogenic constructs starting from the stromal vascular fraction (SVF) of human adipose tissue as a single cell source. SVF cells from human lipoaspirates were seeded and cultured for 5 days in porous hydroxyapatite scaffolds by alternate perfusion through the scaffold pores, eliminating standard monolayer (two-dimensional [2D]) culture. The resulting cell-scaffold constructs were either enzymatically treated to extract and characterize the cells or subcutaneously implanted in nude mice for 8 weeks to assess the capacity to form bone tissue and blood vessels. SVF cells were also expanded in 2D culture for 5 days and statically loaded in the scaffolds. The SVF yielded 5.9 +/- 3.5 X 10(5) cells per milliliter of lipoaspirate containing both mesenchymal progenitors (5.2 units) and endothelial-lineage cells (54 cells). After 5 days, the total cell number was 1.8-fold higher in 2D than in three-dimensional (31)) cultures, but the percentage of mesenchymaland endothelial-lineage cells was similar (i.e., 65 of CD90(+) cells and 7 implantation, constructs from both conditions contained blood vessels stained for human CD31 and CD34, functionally connected to the host vasculature. Importantly, constructs generated under 3D perfusion, and not those based on 2D-expanded cells, reproducibly formed bone tissue. In conclusion, direct perfusion of human adiposederived cells through ceramic scaffolds establishes a 3D culture system for osteoprogenitor and endothelial cells and generates osteogenic-vasculogenic constructs. It remains to be tested whether the presence of endothelial cells accelerates construct vascularization and could thereby enhance implanted cell survival in larger size implants

In vitro and in vivo validation of human and goat chondrocyte labeling by green fluorescent protein lentivirus transduction

We investigated whether human articular chondrocytes can be labeled efficiently and for long-term with a green fluorescent protein (GFP) lentivirus and whether the viral transduction would influence cell proliferation and tissue-forming capacity. The method was then applied to track goat articular chondrocytes after autologous implantation in cartilage defects. Expression of GFP in transduced chondrocytes was detected cytofluorimetrically and immunohistochemically. Chondrogenic capacity of chondrocytes was assessed by Safranin-O staining, immunostaining for type II collagen, and glycosaminoglycan content. Human articular chondrocytes were efficiently transduced with GFP lentivirus (73.4 +/- 0.5% at passage 1) and maintained the expression of GFP up to 22 weeks of in vitro culture after transduction. Upon implantation in nude mice, 12 weeks after transduction, the percentage of labeled cells (73.6 +/- 3.3%) was similar to the initial one. Importantly, viral transduction of chondrocytes did not affect the cell proliferation rate, chondrogenic differentiation, or tissue-forming capacity, either in vitro or in vivo. Goat articular chondrocytes were also efficiently transduced with GFP lentivirus (78.3 +/- 3.2%) and maintained the expression of GFP in the reparative tissue after orthotopic implantation. This study demonstrates the feasibility of efficient and relatively long-term labeling of human chondrocytes for co-culture on integration studies, and indicates the potential of this stable labeling technique for tracking animal chondrocytes for in cartilage repair studies