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While some attempts have been made to model the behaviour of the grand piano action (the mechanism that translates a key press into a hammer striking a string), most researchers have reduced the system to a simple model with little relation to the components of a real action. While such models are useful for certain applications, they are not appropriate as design tools for piano makers, since the model parameters have little physical meaning and must be calibrated from the behaviour of a real action. A new model for a piano action is proposed in this thesis. The model treats each of the five main action components (key, whippen, jack, repetition lever, and hammer) as a rigid body. The action model also incorporates a contact model to determine the normal and friction forces at 13 locations between each of the contacting bodies. All parameters in the model are directly measured from the physical properties of individual action components, allowing the model to be used as a prototyping tool for actions that have not yet been built. To test whether the model can accurately predict the behaviour of a piano action, an experimental apparatus was built. Based around a keyboard from a Boston grand piano, the apparatus uses an electric motor to actuate the key, a load cell to measure applied force, and optical encoders and a high speed video camera to measure the positions of the bodies. The apparatus was found to produce highly repeatable, reliable measurements of the action. The behaviour of the action model was compared to the measurements from the experimental apparatus for several types of key blows from a pianist. A qualitative comparison showed that the model could very accurately reproduce the behaviour of a real action for high force blows. When the forces were lower, the behaviour of the action model was still reasonable, but some discrepancy from the experimental results could be seen. In order to reduce the discrepancy, it was recommended that certain improvements could be made to the action model. Rigid bodies, most importantly the key and hammer, should be replaced with flexible bodies. The normal contact model should be modified to account for the speed-independent behaviour of felt compression. Felt bushings that are modelled as perfect revolute joints should instead be modelled as flexible contact surfaces.

The piano action is the mechanism that transforms the finger force applied to a key into the motion of a hammer that strikes a piano string. This thesis focuses on improving the fidelity of the dynamic model of a grand piano action which has been already developed by Hirschkorn et al. at the University of Waterloo. This model is the state-of-the-art dynamic model of the piano in the literature and is based on the real components of the piano action mechanism (key, whippen, jack, repetition lever, and hammer). Two main areas for improving the fidelity of the dynamic model are the hammer shank and the connection point between the key and the ground. The hammer shank is a long narrow wooden rod and, by observation with a high-speed video camera, the flexibility of this part has been confirmed. In previous work, the piano hammer had been modelled as a rigid body. In this work, a Rayleigh beam model is used to model the flexible behaviour of the hammer shank. By comparing the experimental and analytical results, it turns out that the flexibility of the hammer shank does not significantly affect the rotation of the other parts of the piano mechanism, compared with the case that the hammer shank has been modelled as a rigid part. However, the flexibility of the hammer shank changes the impact velocity of the hammer head, and also causes a greater scuffing motion for the hammer head during the contact with the string. The connection of the piano key to the ground had been simply modelled with a revolute joint, but the physical form of the connection at that point suggests that a revoluteprismatic joint with a contact force underneath better represents this connection. By comparing the experimental and analytical results, it is concluded that incorporating this new model significantly increases the fidelity of the model for the blows. In order to test the accuracy of the dynamic model, an experimental setup, including a servo motor, a load cell, a strain gauge, and three optical encoders, is built. The servo motor is used to actuate the piano key. Since the purpose of the motor is to consistently mimic the finger force of the pianist, the output torque of the motor is controlled. To overcome the problem associated with the motor torque control method used in previous work, a new torque control method is implemented on a real-time PC and a better control of the motor torque output is established. Adding a more realistic model of the piano string to the current piano action model and finding a better contact model for the contacts that happen between the surfaces that are made of felt (or leather), are two main areas that can be worked on in the future research. These two areas will help to further increase the fidelity of the present piano action model.

Many of our daily activities are achieved through goal-oriented routines which illustrates the adaptability and efficiency of information processing. Nevertheless, slips of action do occur. This study was designed to determine if slips of action can be induced in a well learned task and if so, how these slips affect specific indicators of task performance. Thirty (12 male) right-handed undergraduate participants were taught, with arrow cues, a sequence of dominant hand movements. Following this learning phase, a portion of the sequences were altered by either changing the spatial location of the arrow cue or by changing the actual movement goal. Results revealed that participants made numerous action slips which were most prevalent when the movement goal was altered. This suggests that participants were unable to disengage their expected movement plan and thus were vulnerable to errors. In addition to exploring the frequency of action slips we also looked at participants’ reaction and movement times on trials that preceded and followed errors and found that a speed-accuracy trade-off could not account for the slips. We also showed that frequency of slips on our task could reliably predict performance on the SART, a measure of inhibitory control, and the frequency of attention failures in daily living on the ARCES. Overall, the results of this study reveal that action slips can be induced by manipulating a well learned action routine and that the frequency of these induced slips reflects a participant’s tendency to commit action slips in everyday life.

Recently, researchers have found evidence that after a concussion, residual visuomotor control deficits may linger longer than working memory or psychomotor speed deficits. All of the major computer administered test batteries currently in use for concussion management rely on examination of the latter tasks, and lack any measure of visuomotor control. The present research set out to develop a task to measure visuomotor performance. Using a touch-screen computer, the task required participants to point towards or away from (i.e., antipointing) a target in a design simmilar to an anti-saccade task. The task required participants to use visual information to execute controlled movements, and is designed to measure movement planning, execution performance and accuracy. The task was delivered to a large sample of healthy individuals to develop a normative performance data set. A self-report questionnaire was used to identify a small group of individuals from the normative population who were identified with a prior history of concussion. These individuals were directly contrasted with the healthy individuals. While only a few reported moderate or severe concussions, and information about recency and number of occurrences was unavailable, performance differences were observed --providing evidence of residual deficits. In particular, while concussed individuals were not slower, or less accurate overall than the healthy population on the task, they demonstrated unusual hand and spatial asymmetries. Future research will compare recently concussed individuals with the normative set developed here, and will make direct comparisons with existing computer administered test batteries to determine the efficacy of visuomotor tasks for detecting the long-term effects of concussion.

The thesis introduces a novel search paradigm, and explores a previously unreported behavioural error detectable in this paradigm. In particular, the ‘Unpacking Task’ is introduced – a search task in which participants use a computer mouse to sort through random heaps of items in order to locate a unique target. The task differs from traditional search paradigms by including an active motor component in addition to purely perceptual inspection. While completing this task, participants are often found to select and move the unique target item without recognizing it, at times continuing to make many additional moves before correcting the error. This ‘unpacking error’ is explored with perceptual, memory load, and instructional manipulations, evaluating eye-movements and motor characteristics in additional to traditional response time and error rate metrics. It is concluded that the unpacking error arises because perceptual and motor systems fail to adequately coordinate during completion of the task. In particular, the motor system is found to ‘process’ items (i.e., to select and discard them) more quickly than the perceptual system is able to reliably identify those same items. On those occasions where the motor system selects and rejects the target item before the perceptual system has had time to resolve its identity, the unpacking error results. These findings have important implications for naturalistic search, where motor interaction is common, and provide further insights into the conditions under which perceptual and motor systems will interact in a coordinated or an uncoordinated fashion.

Past research has demonstrated that there are numerous medical and psychological consequences when a woman with an eating disorder becomes pregnant. There has been a paucity of research, however, examining the attitudes towards pregnancy of women with body image issues/eating disorders and how these attitudes subsequently affect intentions to become pregnant. The present study examines intentions to become pregnant among a sample of women ranging in level of body image concerns using the Theory of Reasoned Action (TRA) as a framework (Ajzen and Fishbein, 1980). Two hundred and forty-two females from an introductory psychology class completed a questionnaire, including the Eating Disorder Inventory (Garner, 1991) and specific scales targeting the components of the TRA developed for the present study. As expected, all TRA precursors to intentions were positively correlated with intentions to become pregnant, while contrary to predictions, body image was not correlated with intentions. In partial support of the TRA, a multiple regression analysis revealed that, for all participants, the subjective norm of pregnancy and perceived benefits of pregnancy were predictive of intentions to become pregnant. Perceived costs of pregnancy, however, evidenced no ability to predict intentions to become pregnant. Although results failed to support the prediction that those with high body image concerns would indicate a lower intention to become pregnant, significant differences among those with high versus low body image concerns did emerge. Specifically, participants with high body image concerns reported greater perceived costs of pregnancy as well as a greater likelihood of engaging in weight control behaviours during pregnancy. Implications, as well as practical applications of these findings are discussed.

In a seminal work, Ungerleider and Mishkin (1982) offered substantial evidence that two separate visual pathways coding what/where-- exist within the primate brain. Recently, human evidence has resulted in the what/where pathways being reconsidered in terms of ventral stream (vision for perception) and dorsal stream (vision for action; Goodale & Milner, 1992). Consistently, many studies have demonstrated that there is an overrepresentation of magnocellular (luminance) information within the dorsal stream; parvocellular input (colour, shape, consistancy) represents the primary source of information for the ventral stream. Although luminance contrast is important in perceiving moving objects, colour discrepancies help the visual system to identify the detailed characteristics of the environment and, subsequently, to prepare the motor system for action. This thesis endeavors to determine the role played by colour, in contrast with luminance, in influencing the programming and control movement production. Using a grasping paradigm and two different luminance conditions (iso-luminance vs. heteroluminance) within two separate experiments (experiment 1 programming; experiment 2 online control), we show that chromatic information can be successfully be used by motor circuits to complete the grasping task faultlessly. Although significant temporal delays in terms of reaction time and movement time between colour and luminance processing are identified, the human visual system seems able to fully integrate colour features for action with no significant spatial error cost.

Research continues to suggest that young women experience body image concerns; nevertheless, the majority of this body image research has focused on white women, and the experiences of young Aboriginal women have typically been overlooked. When research has included Aboriginal women, it has generally been quantitative in nature (e.g., Gittelsohn et al., 1996; Marchessault, 2004; Story et al., 1995) and has highlighted body dissatisfaction that is equal to and even greater than that experienced by white women. Despite the alarming statistics suggesting that body image concerns are common among Aboriginal women, few researchers have engaged young Aboriginal women in qualitative research projects that seek to highlight their unique experiences. My previous research with young Aboriginal women (i.e., Fleming et al., 2006; McHugh & Kowalski, in press) are some of the first Canadian studies to have an exclusive focus on Aboriginal womens body image experiences. This research suggested that young Aboriginal womens body image experiences may not be as negative as previous quantitative research has suggested, but highlighted the need to work with young women to develop strategies for positively managing body image experiences. Therefore, the purpose of this research was to engage in a collaborative, school-based participatory action research (PAR) project in partnership with a local high school to provide young women, primarily young Aboriginal women, with an opportunity to manage their body image experiences in an effective manner.<p> Students, teachers, and staff of Nutana Collegiate participated in this project, which took place over a 10-month period from September 2006 to June 2007. All Nutana school members were welcomed to participate and many took part in the various action initiatives that were developed. A group of seven young Aboriginal women formed a core group of participants who were primarily responsible for the development and implementation of most action initiatives. A five phase PAR model, which was based on the work of Stringer and Genat (2004), was proposed as the methodological framework for this project. However, given the emergent and dynamic nature of PAR processes, and the unique features of the school community, the manner in which the project actually unfolded was quite different from the original plan. This project ultimately had two phases, the Relationship Building Phase and the Action Phase.<p> In an effort to develop relationships with school community members, during the Relationship Building phase I engaged in the three general processes of: familiarization, making connections, and giving back to the school. My commitment to these processes supported my initial goal to develop trusting relationships with community members, which subsequently formed a strong foundation for the development of effective and successful action initiatives. Eight action initiatives, which were represented by three themes, were developed and implemented as part of the Action phase. The three themes were: (1) Promoting Positive Body Image Experiences, (2) Self-Expression, and (3) Creating Awareness.<p> The development and implementation of action at various levels (i.e., individual, school, provincial, and national) was the most significant outcome of this research. The success and relevance of the various action initiatives was demonstrated by the words of the participants, the overall support of various school members, and the commitment of the core group to the goals of this PAR project. Although there were methodological challenges and considerations that needed to be navigated throughout this PAR project, findings from this research suggest that universities and local high schools can and should work together to develop school-based body image programs for young Aboriginal women. As well, and maybe most importantly, this research highlights the strength of using PAR methodologies when engaging young Aboriginal women in body image research.

En förutsättning för att kunna förhindra att terrorattacker utförs är kunskap om de bakomliggande motiven och drivkrafterna. Om vi känner till de bakomliggande motiven och drivkrafterna finns det möjlighet att kunna påverka dessa faktorer och därigenom minska risken för nya terrorattacker. I den här studien undersöker jag om collective action frames och rational choice teorin var för sig eller tillsammans kan förklara orsakerna till terrorism. Fram till idag har den strategiska modellen varit den mest använda teorin för att förklara orsaker till terrorism. Modellen utgår från rational choice teorin men har avgränsats till att enbart hantera politiska faktorer, vilket har kritiserats. Kritikerna menar att människors känslor har en betydelse för deras handlingar. Här prövar jag två teorier som teoretiskt kan förklara känslornas betydelse för att människor utför terrorhandlingar, dels rational choice teorin och dels collective action frames. Studien visar att teorierna kompletterar varandra men det är enbart rational choice teorin som förklarar orsaker till handlingarna, och då endast rationellt motiverade instrumentella handlingar. Det är många handlingar som inte kan förklaras med någon av teorierna. Slutsatsen är att det sannolikt inte finns en generell teori som kan förklara alla olika typer av handlingar ner till en sådan detaljnivå att resultatet faktiskt är användbart. Det finns många olika motiv och drivkrafter som kan ligga bakom en handling och det finns så många olika användningsområden för resultaten att en enda teori skulle bli oanvändbar då det sannolikt är alldeles för många parametrar att hantera inom ett och samma teoribygge.