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Symmetry – measured as the size asymmetry of a group of symmetrical body traits such as ear height or elbow circumference – has often been used as an index of the capacity to develop normally despite stress and correlates with a wide range of outcomes including intelligence, health and aspects of behaviour. However, theoretical debate continues over the underlying causes of these associations and outstanding methodological issues – such as the reliance on small sample sizes of college age students – makes the robustness of the findings uncertain. The present work advances the existing empirical literature in six separate domains. It also improves upon past methodology by using novel methods of digital measurement of asymmetry as well as for the first time digitally measuring endogenous asymmetry as indexed by the bones and linking bone asymmetry to intelligence. The research was conducted on four samples. Numbers given are for participants who provided asymmetry measures. Firstly, a sample of elderly participants from the Lothian Birth Cohort 1921 (LBC1921, n = 216) tested around ages 11, 79, 83, and 87. Secondly, the Science Festival Sample (SFS), a group of children recruited at a public science event aged between 4 and 15 (n = 856). Thirdly, a group of Orkney residents aged 18 to 86 (the ORCADES, n = 1200). Fourthly the Berlin Sample (BS), a group of Berlin residents (n = 207) between 20 and 30 years old. In the LBC 1921, men with poorer socioeconomic status in childhood had higher facial asymmetry in old age (β = -.25, p = .03). While investigating issues related to asymmetry in the same sample it was found that relatively more severe digit curvature – a minor physical anomaly – was associated with relatively greater cognitive decline (β = -.19, p = .02). Within the SFS asymmetry decreased across human childhood (β = -.16, p = .01), and more asymmetrical children exhibited slower choice reaction times (β = .0.17, p = .002). In the ORCADES sample, the more asymmetrical participants (as indexed by bone asymmetry) were less intelligent (β = -.24, p = .01). In the Berlin Sample and the LBC 1921 no consistent associations were found between personality traits and asymmetry. Collectively, these findings suggest symmetry functions as a measure of overall well-being as the trend is for higher asymmetry to be associated with a relatively poorer score on a variety of outcome measures. The findings considerably expand the number of existing studies in these empirical areas and in several cases – particularly asymmetry’s association with socioeconomic status in the elderly and reaction times among children – represent the first work on those areas. The present work confirms the finding that asymmetry is linked to adverse outcomes. However, the underlying mechanisms by which symmetry is linked to such outcomes remain underexplored and require clarification.

This thesis sought to identify and evaluate the effects of suppressing anger on cognition and behaviour from both naturalistic and laboratory approaches.  It was predicted that anger suppression places demands on valuable cognitive resources and it was predicted that this form of emotion regulation would have detrimental effects on thinking and reasoning abilities.  A naturalistic study examined records of everyday anger experiences (as documented in daily diaries) and showed that anger suppression had negative effects on participants’ self-reports of concentration, critical thinking, decision-making and accuracy in the formation of judgements.  The first laboratory experiment explored the effects of anger suppression on critical thinking and reasoning abilities through tests of analysis, evaluation and assumption.  The second laboratory experiment investigated performance on social reasoning skills utilising theory of mind tasks to assess interpersonal perception and inference abilities.  The results of the laboratory experiments showed that relative to expression, suppression was associated with superior cognitive performance on specific measures of critical and social reasoning.  Overall, the findings were inconsistent and did not provide full support for the proposal that regulating anger through suppression has detrimental cognitive effects, particularly with respect to critical thinking and reasoning abilities.  The implications of these findings and future directions for anger research are discussed.

This study assessed the cognitive impact of ECT using: a paired words and short story test, a spatial and pattern recognition memory subtest, a pattern-location associated learning subtest, a delayed matching to sample subtest, a modified version of Kopelman’s Autobiographical Memory Interview (AMI), and a subjective memory test was also included. Tests were conducted on ECT patients, before treatment (baseline), after four treatments, after the final ECT and one month following the final ECT treatment, to measure short and long-term memory loss. Baseline data was collected from 26 patients, thereafter patient numbers varied (details are reported in the results section). This study found that paired word and a short story tasks were insensitive at detecting cognitive deficits during or after ECT; however a delay of one hour increased the sensitivity of these tests. The visual memory battery detected deficits in visual and visuospatial memory during and immediately following a course of ECT but only spatial recognition memory deficits remained one month post-ECT. The modified AMI appeared to be a sensitive measure of retrograde memory loss. Deficits were observed in both semantic and episodic memory. Memory for recent events displayed the greatest losses. Subjective memory complaints were significantly reduced during, after, and at one month following ECT; however these were highly correlated with depression scores. In conclusion, the battery of neuropsychological memory tests adopted for this study appear to be sensitive to the adverse effect of ECT on aspects of anterograde and retrograde memory loss generally. However, the sensitivity of the subjective test is questionable as outcome on this test appears to be influenced by mood.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Many human behaviours are thought to depend upon cognitive capacities enriched with innate domain-specific knowledge. Underpinning this view is the hypothesis that evolution can shape cognition to include strong innate inductive biases. In this thesis, I re-examine that hypothesis with respect to a broad class of behaviours: those that we learn from other individuals. Taking human language as a test case, I present an analysis of the co-evolutionary process that underpins the formation of innate constraints on cognition for behaviours that are culturally transmitted through inductive inference. I derive a series of mathematical models of this process, built around Bayesian models of cognition and cultural transmission, and ask how they can inform our expectations about cognition in a cultural species. I argue that the traditional marriage of nativism and evolutionary reasoning is undermined by this process, as is the suggestion that cognitive adaptation to cultural behaviours is outright implausible. I explore the co-evolutionary dynamics induced by cultural transmission, and conclude that they can radically manipulate the evolution of cognition: culture can intervene in the formation of hard-wired knowledge, but nevertheless facilitate rapid cognitive adaptation. The analyses I report make strong, testable predictions about the nature of inductive biases for cultural behaviours, and offer solutions to a number of long-standing conundrums in the evolution of language.

Les gens produisent des mouvements spontanés pendant des tâches de raisonnement spatial. Ces mouvements aident-ils à la performance de la tâche? Nous avons étudié le rôle des mouvements spontanés dans l'orientation spatiale en utilisant des tâches de prise de perspective spatiale (PPS) dans lesquelles les participants devaient imaginer un point de vue différent de leur point de vue actuel. Nous nous sommes concentrés sur des perspectives exigeant des rotations mentales de soi - particulièrement difficiles, elles sont grandement facilitées par un mouvement actif, même en l'absence de vision. La contribution motrice à la performance de la tâche pourrait résulter d'un mécanisme prédictif, qui anticipe les conséquences d'une action avant son exécution, comme un modèle d'anticipation interne (Wolpert & Flanagan, 2001), inhibant par la suite l’exécution du mouvement si nécessaire. Les mouvements observés peuvent être des traces visibles de ce processus. En utilisant un système de capture de mouvements, nous avons montré que les rotations de la tête sont géométriquement liées à la PPS : leur direction et amplitude étaient liées à la direction et à l'angle entre les perspectives réelles et imaginée (Exp. 1). Chez les contrôleurs aériens, qualifiés ou apprentis, seule la direction de la rotation de la tête était liée à la PPS, reflétant probablement l'expertise spatiale ainsi que le rôle crucial de la direction dans la rotation mentale (Exp. 2). Dans un environnement virtuel, les rotations de tête spontanées étaient liées à une performance accrue. Cependant, les rotations volontaires, qui imitent celles qui sont produites spontanément, ne facilitent pas la performance de navigation (Exp. 3), mais l'empêchent lorsqu’elles sont contraires à la direction de la rotation virtuelle. Nos résultats suggèrent une contribution motrice spécifique à l'orientation spatiale, compatible avec la prédiction motrice. / People produce spontaneous movements during spatial reasoning tasks. Do they relate to task performance? We investigated the role of spontaneous movements in spatial orientation using spatial perspective-taking (SPT) tasks where participants adopted imaginary perspectives. We focused on imaginary perspectives requiring mental rotations of the self as they are particularly difficult and greatly facilitated by active movement in the absence of vision. Motor contribution to task performance could result from a predictive mechanism, which anticipates the consequences of an action before its execution, such as an internal forward model (Wolpert & Flanagan, 2001), further inhibiting full rotations of the head. Observed movements may be visible traces of this process. Using motion capture, we showed that head movements are geometrically related to SPT: both the direction and amplitude of head rotations were related to the direction and angle between the actual and imagined perspectives (Exp. 1). In air traffic controllers and apprentices, only the direction of head rotation was related to SPT, probably reflecting spatial expertise and its crucial role in mental rotation (Exp. 2). In a virtual environment, spontaneous head rotations were related to increased performance. However voluntary rotations, emulating the spontaneously produced ones, did not facilitate navigation performance (Exp. 3), but hindered it when inconsistent with the direction of virtual rotation. Overall, our findings suggest a specific motor contribution to spatial orientation consistent with motor prediction.

Autism Spectrum Disorder (ASD) is a pervasive developmental disorder characterized by two distinct features; the social, including impairments in communication and social functioning (empathizing), and the non-social, including preoccupation with restricted interests and repetitive behaviours (systemizing). This thesis investigated non-social cognition in the autism spectrum by undertaking six studies, three with neurotypical participants from the general population and three with an ASD group and matched neurotypical controls. These studies measured autonomic arousal to social and non-social stimuli and stimuli associated with the participant's own special interest or hobby, and change blindness tasks that utilized both social and non-social changes, along with measures of attention to detail and anxiety in an attempt to understand some of the cognitive and affective mechanisms that underlie non-social cognition in ASD and in the wider autism spectrum. A further study assessed 'drive to systemize' along with an objective behavioural assessment of logical thinking ability and a measure of preference for deliberative or intuitive thinking style, to try to further elucidate connections between drive to systemize and ability to systemize, and the modes of cognition that relate to systemizing. Findings included the relationship between autistic traits and stronger physiological responses to non-social stimuli in the neurotypical sample, and a significantly stronger response in the ASD group to non-social stimuli related to personal special interest than in controls. Participants with a larger number of autistic traits showed enhanced change blindness when changes were social in nature. Self-reported high systemizers report that they prefer slow, deliberative styles of thinking and provide more accurate responses to questions that should involve logical thinking-yet they are less able to provide sound logical reasoning for their correct answers than those who are low systemizers. Together, the results suggest that non-social cognition, or systemizing, in autism is motivated by bottom up perceptual and affective processes that share features with conventional social and emotional cognition, or empathizing.

Military personnel are required to perform effectively in extreme enviroments. Optimal performance in combat enviroments is a complex process and its neural basis is poorly understood. Understanding the factors that influence how an individual is able to perform to a high standard and cope with the demands of the situation while under extreme operational stress is vital. As stressful events can have a lasting impact on soldiers and while for some deployment can lead to positive change for others it can increase the risk of suffering from post-traumatic stress disorder (PTSD). To better understand how soldiers are able to perform effectively, in the first study of the thesis we developed a psychometrically robust measure of mental robustness that was informant rated and relevant to combat operations. The measure assesses a soldier’s ability to make decisions under pressure and their ability to function effectively when faced with emotional challenging situations as two separate dimensions. A second study confirmed the factor structure of the measure and also provided initial evidence for its construct validity. The measure underpinned our final study (Study 3) which combined psychometric measures, behavioural and functional imaging to produce a deeper understanding of the relationship between activity in key brain regions and key components of robustness. Study 3 assessed soldier’s ability to make decisions under pressure when presented with combat relevant stimulus. The study employed two tasks; Task 1 required individuals to attend to emotional aspects of the stimuli as they would do in during combat and Task 2 required soldiers to attend to the non-emotional aspects of the stimuli. Our findings suggest that robustness acts as a resistance resource and although it does not protect against PTSS it does allow a curvilinear relationship between PTSS and performance. The ultimate goal of this thesis is to better understand the critical factors required for optimal military performance during deployment. This will allow more targeted training that will help highly motivated individuals achieve excellence.