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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
721

Temporal mach bands: a psychophysical study

Kirkwood, B. J. January 1979 (has links)
Five experiments were carried out to discover whether there is a subjective enhancement of temporal contours analogous to the Mach band effects in spatial vision. A transient overshoot in the incremental threshold occurred immediately after the crest of rising linear ramps at photopic levels. A psychophysical matching experiment verified that this peaking effect is perceived as a bright pulse and can be considered the temporal equivalent of the bright Mach band. No equivalent of the dark Mach band at the foot of rising linear ramps was found. Rather there was an anticipatory decrease of sensitivity (Crawford effect) at the base of ascending gradients. The magnitude of this effect was directly proportional to the rate of change of the stimulus at photopic levels. Data from descending ramps was less simple to interpret. A small rise in incremental threshold was sometimes observed at the crest of ramps, but this effect was much less pronounced than the peak at the crest of equivalent ascending ramps. Matching procedures located troughs at the foot of descending ramps which correspond to the dark spatial Mach band. This effect was less apparent when incremental threshold techniques were employed. An experiment using exponential rather than linear change in luminance over time gave results in general accord with the above. The Crawford effect was found to follow the Bunsen-Roscoe Law. It was found that the transient undershoot and overshoot effects were related to the rate of change rather than the actual form of the ramp when the rate of change was greater than about 300mL per second. Impulse responses were derived by differentiating step responses. Ascending steps generated a biphasic impulse response and descending steps give a triphasic unit impulse response. This lack of equivalence over conditions is diagnostic of system nonlinearity. Fourier analysis of the impulse responses showed equivalent spectral components and lowpass filter action in each case, indicating change in gain and phasing rather than time constants occur between 'on' and 'off' conditions. The system was shown to be quasilinear within conditions since linear convolution of the impulse responses with appropriate ramps generated functions that were a fair approximation to the psychophysical response to such ramps. The relationship between the impulse response and the spatial equivalent line spread function was discussed and the similarity of the impulse responses to dynamic changes in sensitivity inferred from results of masking experiments pointed out. The results were then considered in relation to a multichannel model for processing spatiotemporal information.
722

Emotional child abuse and resiliency: an Aotearoa/New Zealand study

McDowell, Heather January 1995 (has links)
Emotional child abuse is recognised as the unifying construct of child abuse (Brassard & Gelardo, 1987). Defining emotional child abuse (ECA) is an area of debate in the literature and a widely recognised definition has yet to be developed. There is general agreement on the definition of resilience with most making reference to adapting and coping well in the face of adversity. Recent research has questioned the implied unidimensionality of the term. A research study was designed with several aims: to explore how ECA is defined by professionals working in the area of child abuse, and by members of the general public; to develop an understanding of the nature of ECA from adults who self-identified as having experienced ECA; and, to examine the ways in which these adults coped, and dealt with ECA and its effects. Further aims of the research following from these were to develop a definition of ECA, and to identify implications for practice for those working in the area of ECA. Attachment theory (Bowlby, 1969, 1988; Crittenden & Ainsworth, 1989) was the theoretical base for the research. The literature on resilience was reviewed with a particular focus on ECA. Consistent findings in the literature on the cost of resiliency in the area of emotional well-being and functioning were explored and used to critically examine the clinical utility of the term. Two surveys were developed, one for distribution to all the professionals working in the area of child abuse in statutory agencies in Auckland; and one for distribution to a sample of adults living in the greater Auckland area. Comparison of the conceptual and specific categories derived from the definitions of ECA provided by the professional group (N=l8l) and the lay group (N=142) indicated considerable agreement. Differences between the groups on the relative frequency of use of the categories were explained and directions for future research were suggested. Concurrence between the findings of this study and others on developing a definition of ECA supported the existence of ECA as a separate and consistent form of child maltreatment. Adults who saw themselves as having experienced ECA were identified through the general public and professional surveys (N=30). They were individually interviewed using a semi-structured format about the nature of the ECA they had experienced and how they had coped with it as a child, adolescent, and adult. The interviews, and relevant material from the surveys, were analysed using a Grounded Theory approach. The themes that emerged from the material on the nature of ECA were grouped into four areas: the nature of ECA; the effects of ECA; the context of ECA; and, disclosure of ECA. The themes that emerged on how participants coped and dealt with the ECA they had experienced revealed a range of coping strategies and changes in these across the broad developmental stages of childhood, adolescence, and adulthood. An important distinction that emerged was that between coping with the ECA and dealing with it. The cost of coping was a prominent theme and concurred with findings in the literature. The implications for practice and directions for future research generated by these findings are discussed. A theoretical definition developed from the research findings is presented and applied to specific examples from the research.
723

About turn:neural mechanisms underlying visual processing of rotated letters and digits

Milivojevic, Branka January 2007 (has links)
This thesis explores neural activity associated with processing of rotated alphanumeric characters, focusing particularly on linear and quadratic trend components of orientation-dependent activity. Choice of these components was driven by results of reaction-time (RT) studies; judging whether characters are normal or backward (parity task) typically elicit RTs that are linearly related to character disorientation, implying mental rotation of the characters to the upright, while judging whether they are letters or digits (categorisation task) elicits RTs related nonlinearly to disorientation, combining both linear and quadratic component, but not indicative of mental rotation. In Experiment 1 neural activity was monitored using fMRI while participants performed these tasks. In the next two experiments, neural processing was monitored with high-density EEG. In Experiment 2 participants performed the same two tasks, while in Experiment 3 they performed the category task and red-blue colour judgements. In Experiment 1, linear increases in fMRI activation were elicited only by the parity task and were observed in the posterior portion of the dorsal intraparietal sulcus and lateral and medial pre-supplementary motor areas, suggesting a fronto-parietal network underlying mental rotation. Experiment 2 showed that linear increases in parietal negativity between 350 and 710 ms only evident in the parity task, again indicating that mental rotation is only elicited by that task. Contrary to previous evidence, Experiment 2 indicated that both hemispheres may be involved in mental rotation, but rotation is faster in the right hemisphere than in the left hemisphere. Experiment 1 also showed that effects of orientation common to both tasks were best characterised by a quadratic trend, and were restricted to the supramarginal gyrus. This activation was interpreted as representing orientation-dependent shape recognition. Experiments 2 and 3 also revealed orientation-dependent neural activity at three distinct stages prior to mental rotation. First, on the P1 component, there was a difference between oblique and vertical orientations, suggesting the extraction of orientation based on axis of elongation. Next, orientation affected the N1 component, with longer latencies and larger amplitudes with misorientation, and smaller effects for inversion than for intermediate angular rotations. Finally, changes in orientation affected the P2 component differently for the parity and category tasks, probably signalling the perception of orientation relative to a parity-defined memory representation, and serving as a preparation for mental rotation. These experiments identify both the orientation-specific neural processing that occurs prior to the onset of mental rotation, and the subsequent neural correlates of mental rotation itself. / Top Achiever Doctoral Scholarship, University of Auckland Doctoral Scholarship, The New Zealand Neurological Foundation, University of Auckland Research Fund (Project numbers: 3607199, 3605876 3604420)
724

Testing and extending self-control theory of crime : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Psychology at Massey University

Williams, Mei Wah January 2007 (has links)
Self-control theory of crime has had considerable impact on mainstream criminology since it was first published in 1990 by Gottfredson and Hirschi. It is regarded as the most parsimonious criminological theory currently available and has been empirically tested across diverse populations and behaviours. Considerable empirical evidence supports the generality of self-control in predicting crime and analogous behaviours, with low self-control ranked as one of the strongest risk factors for crime. Of substantive concern however is a lack of explanatory power in the theory, a problem that besets criminological theorising in general. This study attempted to integrate self-control theory with theory of planned behaviour (TPB). Whilst self-control provides a stable-dispositional explanation for propensity to crime, TPB is interested in the decision-making processes related to involvement in crime. As such, the study examined the relationship between time-stable self-control and the mediating role of situational-specific factors in the causation of crime. The purpose of the study is twofold. Firstly to investigate the underlying mechanism by which a person with low self-control may have greater propensity to crime and secondly to increase the explanatory value of self-control theory. Three disparate groups were used to explore the single theories and the integrated theory; female students, male students, and prison inmates. Confirmatory factor analysis and structural equation modelling were conducted to examine the sufficiency of the theories to explain intention to commit crime across three groups. Low self-control was unable to explain behavioural intentions for students but was successful in explaining intentions to do crime in a prison population. The motivational elements of TPB, subjective norm and perceived behavioural control, were shown to exert considerable influence on intention to do crime across the three samples but not attitude. The integrated theory increased the explanatory value of self-control theory for prison inmates over and above its constituent theories. These findings were not replicated with male and female students, raising questions about the generality of self-control theory. Implications for self-control theory are discussed, especially the need to include significant others and behavioural control variables in understanding the causes of crime
725

The Social Identity of Teams at Work

Lembke, Swantje (Svan) January 1997 (has links)
This dissertation investigates the management of teams at work. A thorough examination of the literature on small groups, coupled with field research on the implementation of teamwork in the New Zealand operations of a large multinational provides insights about how members of a team think. It is shown that the perception of membership by team members influences their ability to make effective use of resources and make informed decisions, not only within the team, but also with regard to its impact on the organisation. Social identity theory provides a theoretical model for the psychological processes of team membership. The processes of categorisation, self-categorisation and social identification are mapped against the introduction of teamwork over a period of two years to assess whether or not they are relevant. The results from surveys of and interviews with senior staff members support the processes described by social identity theory, where groups can operate as separate cognitive and emotional units as relevant for the management of teams at work. Because of the unique psychological processes, team members at work have to be interacted with (and be given information) differently than individuals in order to behave as a high-performing team. This study develops the implications of social identity theory for the introduction and management of teams at work, leading to high performance for the organisation. Key words: Teamwork, social identity, social cognition
726

Temporal mach bands: a psychophysical study

Kirkwood, B. J. January 1979 (has links)
Five experiments were carried out to discover whether there is a subjective enhancement of temporal contours analogous to the Mach band effects in spatial vision. A transient overshoot in the incremental threshold occurred immediately after the crest of rising linear ramps at photopic levels. A psychophysical matching experiment verified that this peaking effect is perceived as a bright pulse and can be considered the temporal equivalent of the bright Mach band. No equivalent of the dark Mach band at the foot of rising linear ramps was found. Rather there was an anticipatory decrease of sensitivity (Crawford effect) at the base of ascending gradients. The magnitude of this effect was directly proportional to the rate of change of the stimulus at photopic levels. Data from descending ramps was less simple to interpret. A small rise in incremental threshold was sometimes observed at the crest of ramps, but this effect was much less pronounced than the peak at the crest of equivalent ascending ramps. Matching procedures located troughs at the foot of descending ramps which correspond to the dark spatial Mach band. This effect was less apparent when incremental threshold techniques were employed. An experiment using exponential rather than linear change in luminance over time gave results in general accord with the above. The Crawford effect was found to follow the Bunsen-Roscoe Law. It was found that the transient undershoot and overshoot effects were related to the rate of change rather than the actual form of the ramp when the rate of change was greater than about 300mL per second. Impulse responses were derived by differentiating step responses. Ascending steps generated a biphasic impulse response and descending steps give a triphasic unit impulse response. This lack of equivalence over conditions is diagnostic of system nonlinearity. Fourier analysis of the impulse responses showed equivalent spectral components and lowpass filter action in each case, indicating change in gain and phasing rather than time constants occur between 'on' and 'off' conditions. The system was shown to be quasilinear within conditions since linear convolution of the impulse responses with appropriate ramps generated functions that were a fair approximation to the psychophysical response to such ramps. The relationship between the impulse response and the spatial equivalent line spread function was discussed and the similarity of the impulse responses to dynamic changes in sensitivity inferred from results of masking experiments pointed out. The results were then considered in relation to a multichannel model for processing spatiotemporal information.
727

Angels at our tables: New Zealanders' experiences of hearing voices

Beavan, Vanessa January 2007 (has links)
The aim of this study was to explore the experience of hearing voices in the general New Zealand adult population. This included mapping the topography of voices and the impact of the experience on participants’ lives, exploring participants’ explanatory models, investigating coping strategies and support structures, and developing a model of the essence of hearing voices. Quantitative and qualitative analyses of questionnaire (n=154) and interview (n=50) data revealed a great diversity of experiences, both within and among participants. Of all topographical variables significantly related to emotional impact (content, form, duration, intrusiveness and control), voice content was the only significant predictor variable, accurately predicting the emotional response of 93.3% of participants. Overall, participants who valued their voice experiences tended to have spiritual beliefs, a more positive emotional reaction and less contact with mental health services. In contrast, participants who experienced mostly unwanted voices tended to have biological and/or psychological understandings of their voice experiences, a more negative emotional reaction to them, and increased contact with mental health services. Participants reported using a vast array of coping strategies, with varying degrees of success. Individualised techniques were reported to be the most effective, followed by setting aside a time to listen to the voices. In terms of help and support, participants called for a model of intervention that accepted their voice experiences as real, took an holistic approach incorporating contextual, cultural and spiritual factors, and worked with voice-hearers, their families and the public to provide information about voice phenomena and normalise the experience. Using a phenomenological approach, a model of the essential structure of hearing voices is proposed, comprising five components: the content of the voices is personally meaningful to the voice-hearer; the voices have a characterised identity; the person has a relationship with their voices; the experience has a significant impact on the voice-hearer’s life; and the experience has a compelling sense of reality. The implications of this research include validating voice-hearers’ perspectives of the experience, informing clinical work with voice-hearers, and informing the development of local and national-level services, such as a New Zealand Hearing Voices Network.
728

Exploring the relationship between family involvement and outcome in residential interventions for children

Woodfield, Melanie Joslyn January 2005 (has links)
Family participation in residential interventions for children has been reliably shown to enhance children’s adaptation to the community following discharge. This finding, however, had predominantly been observed in long-term residential programmes in North America. This thesis examines the influence of family involvement on outcome for children in a short-term residential intervention - the Children’s Health Camp, in Auckland, New Zealand. This service offers children and families, who may be experiencing social, emotional, physical and/or behavioural challenges, individualised interventions that often include a five-week residential stay. A ‘high family involvement’ condition, a community-based programme that followed a residential intervention, was compared with a ‘low family involvement’ condition (the traditional residential programme). No statistically significant differences were observed between the groups on parent-report measures of child behaviour and parenting practices, although significant improvements in children’s behaviour (including emotional, social and conduct aspects) for both groups were found. Reasons for the lack of difference between the groups, and the difficulties inherent in conducting outcome research in a residential facility for children are highlighted. Other influences on outcome for children and families, such as residential staff members’ attitudes toward family involvement were also examined. The optimal conditions for successful short-term residential interventions for children are proposed.
729

Logical modelling of reasoning and learning : a bio-inspired approach / Modélisation logique du raisonnement et de l’apprentissage : une approche bio-inspirée.

Grimaud, Christel 31 March 2016 (has links)
Dans ce mémoire, on s’inspire des sciences cognitives pour aborder la question de la modélisation logique du raisonnement et de l’apprentissage. Notre principale conviction est qu’il faudrait, pour traiter ce problème, prendre modèle sur la manière dont les agents naturels (c’est à dire les humains et les animaux) procèdent lorsqu’ils raisonnent ou apprennent. Considérant que le raisonnement fait appel à un grand nombre de facultés cognitives distinctes, et qu’il ne serait donc pas raisonnable d’espérer modéliser d’un seul coup l’ensemble du raisonnement humain, on se concentre ici sur un type d’inférences très simples dont on soutient qu’elles constituent le coeur du raisonnement chez tous les animaux à cerveau. On identifie un processus sous-jacent plausible pour ces inférences, d’abord au niveau mental de description, puis au niveau neuronal, et on développe une famille de modèles logiques permettant de le simuler. On s’attache ensuite à produire un ensemble de règles d’inférence caractérisant les relations d’inférence induites par ces modèles. Ces règles résultent du processus suggéré, et doivent donc être vues comme des règles qui, d’après le modèle, émergent fonctionnement des cerveaux. Enfin, on analyse les processus d’apprentissage attachés aux inférences considérées, et on montre comment le formalisme proposé permet de les modéliser. Pour conclure on évoque brièvement les possibles développements futurs du modèle, et notamment on donne quelques indications quant à la manière dont la modélisation d’un certain nombre de facultés additionnelles pourrait être envisagée. / In this dissertation, we take inspiration in cognitive sciences to address the issue of the logical modelling of reasoning and learning. Our main thrust is that to address these issues one should take inspiration in the way natural agents (i.e., humans and animals) actually proceed when they draw inferences and learn. Considering that reasoning incorporates a wide range of cognitive abilities, and that it would thus be unreasonable to hope to model the whole of human’s reasoning all at once, we focus here on a very basic kind of inferences that, we argue, can be considered as the primary core of reasoning in all brained animals. We identify a plausible underlying process for these inferences, first at the mental level of description and then at the neural level, and we develop a family of logical models that allow to simulate it. Then we tackle the issue of providing sets of rules to characterise the inference relations induced by these models. These rules are a by-product of the posited process, and should thus be seen as rules that, according to the model, result from the very functioning of brains. Finally we examine the learning processes attached to the considered inferences, and we show how to they can be modelled within our framework. To conclude we briefly discuss possible further developments of the framework, and in particular we give indications about how the modelling of some other cognitive abilities might be envisioned.
730

Executive functions for Learning and decision-making in a bio-inspired cognitive architecture = Funções executivas para aprendizado e tomada de decisão em uma arquitetura cognitiva bio-inspirada / Funções executivas para aprendizado e tomada de decisão em uma arquitetura cognitiva bio-inspirada

Raizer, Klaus, 1982- 27 August 2018 (has links)
Orientador: Ricardo Ribeiro Gudwin / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-27T01:31:15Z (GMT). No. of bitstreams: 1 Raizer_Klaus_D.pdf: 4879759 bytes, checksum: 77716297b6419a3ee55bdf97ac67493d (MD5) Previous issue date: 2015 / Resumo: O objetivo deste trabalho é o desenvolvimento de funções executivas para uma arquitetura cognitiva bioinspirada baseada em codelets. Um desafio que toda criatura (seja ela artificial ou biológica) enfrenta é definir qual a próxima ação a ser tomada, a cada instante de tempo, em função da percepção de um determinado ambiente. Essa decisão pode ser definida por um algoritmo que sempre repete as mesmas decisões em função de uma determinada situação, ou pode ser uma decisão adaptativa, que utiliza de mecanismos de aprendizagem para assumir decisões distintas, em função das experiências em situações passadas. Neste trabalho, buscou-se a integração dos processos de tomada de decisão deliberativos e mecanismos de aprendizado por reforço em um mesmo framework. Estas funções são conhecidas na literatura de ciências cognitivas como funções executivas. A solução aqui proposta insere-se dentro do contexto de nosso grupo de pesquisa, onde se busca o desenvolvimento de uma arquitetura cognitiva baseada em codelets. Nesta perspectiva, uma das contribuições deste trabalho é desenvolver algoritmos e implementações computacionais dotando a arquitetura cognitiva desenvolvida pelo grupo de funções executivas diversas, que poderão ser utilizadas para implementar soluções complexas com granularidade arbitrária. As funções de tomada de decisão deliberativa foram implementada na forma de uma rede de comportamentos modificada, enquanto que o componente de aprendizado foi desenvolvido na forma de um novo algoritmo (GLAS - Gated-Learning Action Selection) baseado em stimulus gating e inspirado em modelos de neurociência computacional conhecidos da literatura. Este framework foi validado em problemas de robótica móvel e de seleção de ação por aprendizado por reforço. A arquitetura cognitiva sendo desenvolvida, incrementada com as contribuições deste trabalho, tem o potencial de servir de base para futuros trabalhos de pesquisa nas áreas de inteligência artificial, robótica e cognição artificial / Abstract: This work¿s goal is the development of executive functions for a codelet-based bio-inspired cognitive architecture. One of the major challenges every creature faces, being biological or artificial, is to define the next action to be taken, at each time step, as a function of how it perceives its surrounding environment. This decision can be made by a reactive algorithm, which always repeats the same decisions for a given situation, or by an adaptive process, which is able to make use of learning mechanisms in order to make distinct decisions based on past experience. In this work, deliberative decision-making and reinforcement learning mechanisms have been integrated into a single framework. In cognitive science literature, these functions are known as executive functions. The solution proposed here is part of our group¿s central line of research, which is the investigation and development of a codelet-based cognitive architecture. In this context, a central contribution made by this work is the development and implementation of algorithms capable of providing this cognitive architecture with a group of executive functions, which in turn can be used to implement complex solutions with arbitrary granularity. Functions for deliberative decision-making have been implemented in the form of a modified behavior network, while the learning component was developed in the form of a new algorithm called GLAS (Gated-Learning Action Selection), based on stimulus gating and known computational neuroscience models. This framework has been validated with problems in mobile robotics and in action selection by reinforcement learning. The cognitive architecture under development, when incremented by the contributions presented in this work, has the potential to serve as a base for future work and research in the fields of artificial intelligence, robotics and artificial cognition / Doutorado / Engenharia de Computação / Doutor em Engenharia Elétrica

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