Recent research has highlighted that the 'yips' in sport represents a continuum on which choking (anxiety related) and dystonia symptoms anchor the extremes (Smith et al., 2000). Previous research investigating the phenomenon has focussed on the 'yips' being a dystonia and has not considered the psychological experience of the problem in detail (McDaniel, Cummings & Shain, 1989; Sachdev, 1992). The primary aim of this thesis was to see if psychological mechanisms underpin the 'yips' experience and if so relate these to the choking model (Baumeister, 1984). The experimental studies established that individuals who have the 'yips' do experience similar underpinning mechanisms to those cited in Baumeister's (1984) model of choking. These factors included increased anxiety responses, increased self-awareness and attempts consciously to process skilled behaviour. However, the personality traits associated with Baumeister's (1984) model were not supported in this thesis. Baumeister's (1984) contention, that low self-conscious individuals would have a greater disposition towards choking, was not supported. Furthermore, the findings indicated that individuals who were dispositionally high in self-consciousness were more prone to performance decrements under pressure and could be more vulnerable to extreme forms of choking such as the 'yips'. The final aim of this thesis attempted to establish a psychological intervention package that could aid performers who experience the 'yips'. Individuals who experience the problem appear to be unable to image successful performances, and subsequently reinforce negative expectations whenever they attempt to focus on performing. Sufferers also attempt consciously to process their skilled behaviour when they experience stress (Masters, 1992), hence subsequent performances tend to be dominated by the analytical left hemisphere of the brain (Crews, 2001). The psychological intervention strategies were implemented to allow individuals to focus on positive performance expectations that could counteract conscious processing and could subsequently increase activity in the right hemisphere of the brain (Crews, 2001). The findings from these studies established that the use of external imagery and holistic trigger words could help counteract the negative effects of conscious processing and ensure a positive approach to performance. The findings within this thesis can be seen as an initial step towards an understanding of psychological components of the 'yips' experience. Future research should investigate the efficacy of psychological intervention strategies in a number of sports, and test these techniques in ecologically valid competitive conditions. Future research could also usefully examine the aetiology of the 'yips' and establish the relationship between dispositional self-consciousness and the development of the 'yips' in sport.

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In sport, the ability to perform under heightened levels of pressure is one of the largest differences between those who are successful and those who are not. There are a number of phenomena associated with breakdowns in an athlete’s performance in high pressure environments, collectively known as paradoxical performances (Baumeister & Showers, 1986). The two most prevalent and researched forms of paradoxical performance are the yips and choking. Although choking has been identified as playing a key role in understanding the yips, to date, no literature has explored these phenomena simultaneously. The current literature highlights potential mechanisms which may explain the yips and choking, such as the Attentional Control Theory (Eysenck & Derekshan, 2011) and the Conscious Processing Hypothesis (Masters, 1992). However, there is limited literature on the potential predictors that may increase the susceptibility of both these paradoxical performances and those which do, focus on golf. There are three aims of this thesis. The first aim was to develop a definition that best encompasses all aspects of the yips. This was achieved by conducting a systematic review of the yips literature which supported the development of a new two dimensional yips model including individuals with both focal dystonia and choking (type-III). The second aim was to investigate potential predictors associated with both the yips and choking that was achieved by completing two studies. The first explored the lived experiences of elite level archers who have experienced both choking and the yips and revealed a number of potential predictors associated with both the yips and choking. The second study tested these predictors using online questionnaires with elite level archers and golfers, and confirmed two discrete predictive models for yips and choking. The final aim of the thesis was to investigate the potential mechanisms associated with performance under pressure. A lab-based study where golfers and archers performed under both high and low pressure found that pressure elicited a range of psychological, physiological and kinematic changes in performance. The proposed two dimensional model from the systematic review received initial support for its application. A number of participants met the criteria for each of the different classifications: type-I, those who experience focal dystonia like symptoms; type-II, those who experience choking like symptoms and; type-III, those who experience both focal dystonia and choking like symptoms. This thesis also highlights the role of social predictors of the yips and choking with perfectionistic self-presentation being the most influential for those susceptible for the yips. These findings will enable practitioners to have a better understanding to effectively classify those who experience choking and the yips. This will allow practitioners to more effectively intervene with those who experience different classifications of the yips. The thesis also highlights the issues in the current literature that surround the measurement and conceptualisation of the yips type-I, type-II and type-III behaviour and provides future directions.

Recent work has shown that the regulatory fit between global approach/avoidance goals and the local approach/avoidance mechanisms of goal pursuit influence cognition and behavior in predictable ways. A regulatory fit leads to an increase in motivation and engagement relative to a regulatory mismatch. The increase in engagement can lead to an increase in cognitive flexibility on cognitively demanding tasks. This work is composed of three inter-related studies that examine how the fit between global performance incentives and local mechanisms of goal pursuit influence decision-making and categorization. In Study 1 I examine how the interaction between global performance incentives and local goal pursuit mechanisms influences decision-making strategies in an experience-based decision-making paradigm. In this paradigm decision-making strategies can be classified as more exploratory or more exploitative. I find that participants in a regulatory fit would exhibit more exploratory decision-making patterns than participants in a regulatory mismatch. In Study 2 I examine how social pressure is related to approach and avoidance-based performance incentives using two types of category-learning tasks. I test the hypothesis that increasing performance pressure will induce an avoidance-based prevention focus which then interacts with the local mechanism of goal pursuit employed in the task (maximizing points gained or minimizing points lost). Participants either perform an explicit, rule-based category-learning task, or an implicit information-integration category-learning task. Behavioral and model-based analyses support the hypothesis that social pressure induces a prevention focus. When the pressure-induced prevention focus aligns with the local goal-pursuit mechanism participants perform better on the rule-based task, but worse on the information-integration task. Study 3 examines the effects of social pressure on categorization in highly-trained participants. Participants performed over 2500 training trials of either a rule-based or an information-integration category-learning task, and then performed another 640 trials after half received a manipulation designed to raise social pressure. Performance was worse on both the rule-based and information-integration task for participants who were under high social pressure compared to participants under low social pressure. The results from all three projects suggest that motivational incentives have a large effect on cognitively demanding tasks. / text

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We analyze performance under pressure and estimate the causal effect of audience size on the success of free throws in top-level professional basketball. We use data from the National Basketball Association (NBA) for the seasons 2007/08 through 2015/16. We exploit the exogenous variation in weather conditions on game day to establish a causal link between attendance size and performance. Our results confirm a sizeable and strong negative effect of the number of spectators on performance. Home teams in (non-critical) situations at the beginning of games perform worse when the audience is larger. This result is consistent with the theory of a home choke rather than a home field advantage. Our results have potentially large implications for general questions of workplace design and help to further understand how the social environment affects performance. We demonstrate that the amount of support, i.e. positive feedback, from a friendly audience does affect performance. / Series: Department of Economics Working Paper Series

It is widely acknowledged that under situations of heightened pressure, many expert athletes suffer from performance decrements. This phenomenon has been termed ‘choking under pressure’ and has been the subject of extensive research in sport psychology. Despite this attention, gaps in the literature remain leaving opportunities for further advancements in knowledge about the phenomenon, particularly in relation to its underlying processes and the development of appropriate interventions that can be adopted in order to alleviate, or even prevent choking. The present programme of research, in general terms, aimed to develop and test the efficacy of an intervention tool, based on priming, to alleviate choking under pressure. It was acknowledged that such a tool should be matched to the mechanisms that underlie the choking process and although an abundance of research has provided valuable information about these mechanisms, it was identified that there still remains a lack of consensus regarding the most appropriate explanatory theory. Therefore the initial study in this thesis aimed to provide further insight into the processes that govern choking by examining accounts from elite international swimmers of their experiences of performing under high levels of pressure. The results provided further support for the postulation that choking under pressure occurs as a result of a combination of conscious processing hypothesis (Masters, 1992) and processing efficiency theory (Eysenck & Calvo, 1992) and that an optimum level of skill-focused attention is beneficial to performance. The following studies utilised this information as well as that of the existent theories of choking, to develop and examine an effective priming based intervention tool (a scrambled sentence task). Specifically, Studies 2, 3 and 4 examined the amount of residual working memory available after activation of the prime, the optimisation of the priming task and the efficacy of the tool in promoting performance under high pressure respectively. Results revealed support for the efficacy of the tool in reducing online skill-focused attention and promoting performance under both low- and high-pressure conditions. Finally, the general themes that emerged throughout the whole programme of study are discussed, as well as the limitations and recommendations for future research. Implications for coaches, athletes and practitioners are also presented.

Thesis advisor: David A. Karp / A qualitative study based on forty four in-depth interviews with undergraduates experiencing severe difficulties with academic writing, this dissertation examines how structural factors--social class and race in particular--contribute to academic "writer's block." Writing block is more than the "personal trouble" it is typically conceived of being, it is also a "public issue" with definitive structural contributors. All of my subjects perceived writing as a high stakes performance, and their writing blocks can be understood as instances of "choking" in the face of these high stakes. For many working class students, writing block is an expression of dominant cultural capital disadvantage; while for many upper middle class students, writing block represents the psychological costs of privilege. For students with unusual class-race identifications, writing block embodies their liminal social status. In the current economic climate of uncertainty, class status for students across the socioeconomic spectrum has become relatively unstable given individuals' increased risk of downward mobility. As such, academic writing blocks may be construed as angst experienced at the intersection of psychology and structure. This study contributes to and extends the literature on social reproduction in higher education as well as the literature on the price of privilege. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Sociology.

Choking flow plays an integral part not only in the engineered safeguards of a nuclear power plant (NPP), but also to everyday operation. Current pressurized water reactor steam generators operate on the leak-before-break approach. The ability to predict and estimate a leak rate through a steam generator tube crack is an important safety parameter. Knowledge of the maximum flow rate through a crack in the steam generator tube allows the coolant inventory to be monitored accordingly. Here an assessment of the choking flow models in thermal-hydraulics code RELAP5/MOD3.3 is performed and its suitability to predict choking flow rates through small simulated cracks of steam generator tubes is evaluated based on collected experimental data. Six samples of the data were studied in this work which correspond to steam generator tube crack<br>samples 6-11. Each sample has a wall thickness, channel length (L), of 1.14 mm. Exit areas of these samples, 6-11, are 2.280E-06 m^2, 2.493E-06 m^2, 1.997E-06 m^2, 1.337E-06 m^2, and 2.492E-06. Samples 6-11 have a channel length to hydraulics diameter ratio (L/D) between 3.0-5.3. Two separate pressure differentials of 6.89 MPa and 4.13 MPa were applied across the samples with a range of subcooling from 20℃ to 80℃ and 20℃ to 60℃. Flow rates through these samples were modeled using the thermal-hydraulic system code RELAP5/MOD3.3. Simulation results are compared to experimental values and modeling techniques are discussed. It is found that both the Henry-Fauske and Ransom-Trapp models better predict choking mass flux for longer channels. <br> <br> <br>

Multiphase flow is associated with concurrent flow of more than one phase (gas-liquid, liquid-solid, or gas-liquid-solid) in a conduit. The simultaneous flow of these phases in a flow line, may initiate a slug flow in the pipeline. Hydrodynamic slug flow is an alternate or irregular flow with surges of liquid slug and gas pocket. This occurs when the velocity difference between the gas flow rate and liquid flow rate is high enough resulting in an unstable hydrodynamic behaviour usually caused by the Kelvin-Helmholtz instability. Active feedback control technology, though found effective for the control of severe slugs, has not been studied for hydrodynamic slug mitigation in the literature. This work extends active feedback control application for mitigating hydrodynamic slug problem to enhance oil production and recovery. Active feedback Proportional-Integral (PI) control strategy based on measurement of pressure at the riser base as controlled variable with topside choking as manipulated variable was investigated through Olga simulation in this project. A control system that uses the topside choke valve to keep the pressure at the riser base at or below the average pressure in the riser slug cycle has been implemented. This has been found to prevent liquid accumulation or blockage of the flow line. OLGA (olga is a commercial software widely tested and used in oil and gas industries) has been used to assess the capability of active feedback control strategy for hydrodynamic slug control and has been found to give useful results and most interestingly the increase in oil production and recovery. The riser slugging was suppressed and the choke valve opening was improved from 5% to 12.65% using riser base pressure as controlled variable and topside choke valve as the manipulated variable for the manual choking when compared to the automatic choking in a stabilised operation, representing an improvement of 7.65% in the valve opening. Secondly, implementing active control at open-loop condition reduced the riser base pressure from 15.3881bara to 13.4016bara.