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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.
181

Orientação endógena da atenção em ratos por meio de pistas simbólicas / Endogenous orienting of attention in rats using symbolic cues

Wataru Sumi 24 November 2011 (has links)
O teste de atenção encoberta descrito por Posner (1980) vem sendo intensamente utilizado em estudos sobre orientação da atenção visuo-espacial em seres humanos. Mais recentemente, esse teste foi adaptado para avaliação da atenção em ratos, com resultados entusiasmantes, pois parece haver uma analogia entre os fenômenos atencionais envolvendo seres humanos e ratos (ROSNER; MITTLEMAN, 1996; WARD; BROWN, 1996; LUCK E VECERA, 2002). A distinção entre orientação exógena (ou \"automática\", na literatura envolvendo humanos) e endógena (ou \"voluntária\", na literatura envolvendo humanos) da atenção, postuladas principalmente com base nas diferenças do curso temporal da resposta ao alvo visual, foram em parte descritas em ratos; esses trabalhos iniciais sugeriam apenas a ocorrência de respostas automáticas em ratos. Porém, Marote e Xavier (2011) mostraram efeito de validade quando pistas preditivas e não-preditivas precediam o alvo em 200, 400 e 800 ms; porém, esse efeito foi maior quando as pistas preditivas precederam o alvo em 800 ms, o que em humanos é tido como efeito da orientação voluntária da atenção. Dado que na maioria dos estudos envolvendo ratos a pista utilizada é periférica, torna-se difícil distinguir claramente entre a ocorrência de efeitos exógenos e efeitos endógenos da orientação da atenção. No presente estudo avaliamos a orientação encoberta da atenção visuo-espacial em ratos empregando pistas simbólicas preditivas, isto é, um tipo de pista que, em seres humanos, restringiria a orientação da atenção apenas ao componente voluntário. Os resultados mostraram que ratos exibem redução do tempo de reação e aumento na percentagem de respostas corretas a um alvo visual precedido por pista simbólica auditiva preditiva válida em relação à pista inválida. Esse efeito manifestou-se quando o intervalo entre a pista e o alvo foi de 100 ou de 700 ms, mas não quando foi de 400 ms. Esses resultados sugerem a existência de dois tipos de fenômenos usualmente atribuídos à orientação da atenção visuo-espacial, o primeiro determinado pelos efeitos do pareamento repetitivo entre a pista e o alvo (que talvez envolva condicionamento clássico), que se manifesta quando o intervalo entre esses estímulos é da ordem de 100 ms, e o segundo determinado pela orientação endógena da atenção, que se manifesta quando o intervalo é igual ou maior que 700 ms. / The covert orienting of attention task described by Posner (1980) has been extensively used for investigating orientation of visuo-spatial attention in humans. There have been attempts to adapt it for rats, with encouraging results; data revealed that attentional phenomena in humans and rats are partially analogous (ROSNER, MITTLEMAN, 1996; WARD, BROWN, 1996; LUCK and VECERA, 2002). The distinction between exogenous (or \"automatic\", in human literature) and endogenous (or \"voluntary\", in human literature) orienting of attention, relying mainly on differences in the time course of the reaction time to the visual target, was partially described for rats; these early studies indicated that rats exhibited only the automated component of orienting. However, Marote and Xavier (2011) showed validity effects when using either predictive or non-predictive cues preceding the target by 200, 400 and 800 ms; however, this validity effect was greater for predictive cues preceding the target by 800 ms, a result that in human studies is taken as evidence of voluntary orienting of attention. Most of rat studies using this task employ peripheral cues, rendering difficult to distinguish exogenous and endogenous effects of orienting of attention. In the present study orienting of visuo-spatial attention was investigated in rats by using symbolic predictive cues, a kind of cue usually considered to engage voluntary attention in humans. The results showed that rats exhibit a reduction of reaction times and an increase in percentage of correct responses to a visual target preceded by a valid symbolic auditory predictive cue as compared to an invalid cue, when the stimulus onset asynchrony was either 100 or 700 ms, but not when it was 400 ms. These figures suggest that the validity effect in rats is underlied by at least two processes, the first determined by repetitive and contingent cue-target pairings (that might involve classical conditioning) that occurs when the cue-target time interval is about 100 ms, and the second determined by endogenous orienting of attention that occurs when the cue-target time interval is about 700 ms.
182

Estudo multivariável do controle postural humano em resposta a pistas sensoriais somestésicas / Not informed by the author

Cristiano Rocha da Silva 07 October 2016 (has links)
Todo ser humano apresenta oscilações posturais aleatórias durante a postura ereta quieta advindas de mecanismos centrais e periféricos. Um toque suave (LT do inglês light touch) de um dos dedos sobre uma superfície fixa ao solo resulta em uma pista sensorial adicional, que promove uma diminuição das oscilações posturais. Entretanto, há necessidade de se obter maiores conhecimentos sobre mecanismos associados ao LT, tanto no que tange a aspectos sensoriais quanto motores associados ao fenômeno. O presente estudo teve como objetivo avançar no entendimento sobre a influência do LT sobre o comportamento de múltiplas variáveis extraídas durante a postura ereta quieta. O primeiro capítulo investigou quantificadores de oscilações posturais com base em medidas como o centro de pressão (CP), centro de massa (CM) e ângulos segmentares e corporais durante experimentos com condições em superfície estável e instável, com olhos abertos e olhos fechados, comparando as condições com e sem LT. Adicionalmente, foi analisada a coerência espectral entre sinais de eletromiograma de diferentes músculos do corpo e os quantificadores acima elencados nas diferentes condições. Os resultados mostraram que o LT diminui o nível de ativação de alguns músculos, principalmente o músculo gastrocnêmico medial, importante na manutenção do controle postural. A variabilidade dos ângulos segmentares e corporais, conjuntamente com variáveis extraídas do CP e do CM diminuíram em condições com LT. Na análise de coerência o LT promoveu algumas alterações nos padrões de oscilação entre ângulos, CP, CM e sinais de eletromiograma, porém com poucas modificações na fase entre os sinais. Na análise de coerência intermuscular, comparando pares de músculos do lado direito e esquerdo do corpo, observou-se que para os membros inferiores a coerência ocorre geralmente na faixa de 0 a 1-2 Hz (em fase), podendo aumentar a faixa de frequência em situações mais instáveis (sem visão e superfície instável), em que o LT passa a influenciar de maneira mais significativa a coerência entre os sinais. O segundo capítulo deste estudo foi motivado por estudos que mostraram ser possível manipular as entradas sensoriais geradas pelo dedo durante o LT. O presente estudo investigou se a retirada de uma entrada sensorial proprioceptiva associada ao dedo é capaz de alterar a oscilação postural, possibilitando a separação e quantificação da contribuição sensorial cutânea da contribuição proprioceptiva dos músculos do terceiro dedo. O controle postural foi avaliado com os sujeitos de olhos fechados e sobre uma superfície instável. Os resultados indicaram que a retirada da informação sensorial proprioceptiva do dedo diminuiu a variabilidade e a velocidade do CP, indicando que a informação cutânea sem a adição de interferências proprioceptivas pode diminuir as oscilações posturais / Human subjects during upright stance show random postural oscillations which are controlled by the central nervous system. A light touch of an index finger (LT) on a surface fixed to the ground results in an additional sensory cue, which promotes a decrease in postural oscillations. However, there is a need to improve the knowledge about mechanisms associated with LT, both with respect to sensory and motor aspects associated with the phenomenon. This study aimed to further the understanding of the influence of LT on the behavior of multiple variables measured during upright stance. The first chapter analyzed variations of some quantifiers of postural sway based on the center of pressure (CP), center of mass (CM) and joint and body angles during experiments with different surface and vision conditions, with and without LT. In addition, the spectral coherence was analyzed between electromyogram signals from different muscles of the body and the previously listed sway quantifiers. The results showed that LT decreases the level of activation of some muscles, particularly the medial gastrocnemius, an important muscle for the maintenance of posture. Segmental and body angle variability and variables extracted from the CP and CM decreased in conditions with LT. In coherence analysis LT promoted some changes in patterns of oscillation between angles, CP, CM and EMGs, but with few modifications in the phase between the signals. The intermuscular coherence analysis (comparing the right and left muscles pairs of the body) showed that significant changes usually occured in the range of 0 to 1-2 Hz (in phase) for the lower limbs and may increase the frequency range in unstable situations (without vision and unstable surface). In these cases LT starts to affect more significantly the coherence between signals. The second chapter of this study was motivated by results from studies that have shown that it is possible to manipulate the sensory inputs generated by the finger during LT. This study investigated whether the withdrawal of a finger proprioceptive input affects postural sway, allowing an analysis of the effects of cutaneous sensory inputs of the third finger muscles. Postural control was evaluated with the subjects with the eyes closed and on an unstable surface. The results showed that removal of proprioceptive information from the finger flexor muscles decreased the variability and speed of the CP, indicating that cutaneous inputs without proprioceptive information may decrease postural sway
183

Optical methods for enabling focus cues in head-mounted displays for virtual and augmented reality

Hua, Hong 10 May 2017 (has links)
Developing head-mounted displays (HMD) that offer uncompromised optical pathways to both digital and physical worlds without encumbrance and discomfort confronts many grand challenges, both from technological perspectives and human factors. Among the many challenges, minimizing visual discomfort is one of the key obstacles. One of the key contributing factors to visual discomfort is the lack of the ability to render proper focus cues in HMDs to stimulate natural eye accommodation responses, which leads to the well-known accommodation-convergence cue discrepancy problem. In this paper, I will provide a summary on the various optical methods approaches toward enabling focus cues in HMDs for both virtual reality (VR) and augmented reality (AR).
184

The cognitive underpinnings of non-symbolic comparison task performance

Clayton, Sarah January 2016 (has links)
Over the past twenty years, the Approximate Number System (ANS), a cognitive system for representing non-symbolic quantity information, has been the focus of much research attention. Psychologists seeking to understand how individuals learn and perform mathematics have investigated how this system might underlie symbolic mathematical skills. Dot comparison tasks are commonly used as measures of ANS acuity, however very little is known about the cognitive skills that are involved in completing these tasks. The aim of this thesis was to explore the factors that influence performance on dot comparison tasks and discuss the implications of these findings for future research and educational interventions. The first study investigated how the accuracy and reliability of magnitude judgements is influenced by the visual cue controls used to create dot array stimuli. This study found that participants performances on dot comparison tasks created with different visual cue controls were unrelated, and that stimuli generation methods have a substantial influence on test-retest reliability. The studies reported in the second part of this thesis (Studies 2, 3, 4 and 5) explored the role of inhibition in dot comparison task performance. The results of these studies provide evidence that individual differences in inhibition may, at least partially, explain individual differences in dot comparison task performance. Finally, a large multi-study re-analysis of dot comparison data investigated whether individuals take account of numerosity information over and above the visual cues of the stimuli when comparing dot arrays. This analysis revealed that dot comparison task performance may not reflect numerosity processing independently from visual cue processing for all participants, particularly children. This novel evidence may provide some clarification for conflicting results in the literature regarding the relationship between ANS acuity and mathematics achievement. The present findings call into question whether dot comparison tasks should continue to be used as valid measures of ANS acuity.
185

Selection of memory book content: Agreement in content as a function of informant relationship to memory book recipient

Allen, Rebecca J. 29 June 2017 (has links)
This study was designed to determine to what extent provision of personally relevant information and sensory cues would agree between Recipient and Informant for selection of memory book content. Six dyads married to each other an average of 29.17 years (SD = 10.03), between the ages of 43 and 70 years (Mean = 57; SD = 8.39), and cognitively competent (i.e., no diagnosis of cognitive impairment) participated. Participants completed questionnaires independently and provided personally relevant information/memories, aversions towards select memories/topics, and sensory cues on behalf of themselves (as “Recipient) and their spouse (as “Informant”). For provision of personally relevant information/memories, Informant and Recipient was 44.58% in agreement (SD = 14.99). For provision of aversions towards select memories/topics, Informant and Recipient was 24.86% in agreement (SD = 30.81). For provision of sensory cues, Informant and Recipient was 19.6% in agreement (SD = 30.81). Findings suggest that memory books made by others may not include the most important memories of the Recipient, thereby limiting the effectiveness of the memory book. Therefore, efforts should be made to encourage individuals to create a memory book while cognitively competent or share their most meaningful memories with the person who is most likely to make them a memory book if they should need one in the future.
186

The role of cuticular hydrocarbons in determining male reproductive success

Lane, Sarah Marie January 2016 (has links)
Cuticular hydrocarbons (CHCs) are found on the outer cuticle of all terrestrial arthropods. Although their primary function is in desiccation prevention, these compounds have also been shown to play a variety of roles in insect chemical communication, from species and sex recognition to providing cues of dominance and attractiveness. However, despite growing evidence of their versatility as cues, our knowledge of how CHCs are used in mating interactions is limited to Drosophila and field crickets. In this thesis I investigate the roles CHCs play in interactions at each stage of the mating process in the broad-horned flour beetle Gnatocerus cornutus. I assess the relative importance of CHCs in influencing male reproductive success and examine the complex interplay between different episodes of selection and the mechanisms of sexual selection acting on males. I use a combination of behavioural assays, experimental manipulations and gas chromatography. First, I identify the role of CHCs as cues of sperm competition risk and intensity, demonstrating how the presence of male-derived CHCs on the cuticles of virgin females elicits males to adjust their pre- and post-copulatory investment (chapter 2), by providing information on the state of their competitive environment. I then go on to look at the stability of CHCs as cues of sperm competition over time, finding that they are highly sensitive to environmental degradation (chapter 3) and do not persist in the habitat substrate of this species. Next, I investigate how male CHCs determine fighting and mating success. By estimating and comparing the strength and form of sexual selection imposed by male-male competition and female mate choice, I show that male CHCs are subject to strong antagonistic sexual selection (chapter 4). By experimentally manipulating male CHC profile, I then attempt to verify the selection gradients estimated for female choice 3 (chapter 5). However, my experimental manipulation fails to verify the importance of male CHCs for female mate choice. Finally, I explore the role of same-sex sexual behaviour (SSB) in determining male reproductive success (chapter 6). I find evidence to suggest that SSB may in fact be a form of aggression in its own right, and demonstrate that SSB and fighting may provide equivalent means for males to overcome female choice and secure a mating advantage. My results indicate that CHCs play key roles as chemical cues throughout the mating process and significantly impact male reproductive success. My thesis reveals the intricate nature of the relationships between mechanisms of sexual selection, alongside highlighting the need to consider both the social and physical environment when investigating the importance of chemical cues. I discuss the implications of these results for the evolution of male CHCs and how my findings can be used to further our knowledge of this field.
187

The impact of product, service and in-store environment perceptions on customer satisfaction and behaviour

Manikowski, Adam 09 1900 (has links)
Much previous research concerning the effects of the in-store experience on customers’ decision-making has been laboratory-based. There is a need for empirical research in a real store context to determine the impact of product, service and in-store environment perceptions on customer satisfaction and behaviour. This study is based on a literature review (Project 1) and a large scale empirical study (Projects 2/3) combining two sources of secondary data from the largest retailer in the UK, Tesco, and their loyalty ‘Clubcard’ provider, Dunnhumby. Data includes customer responses to an online self-completion survey of the customers’ shopping experience combined with customer demographic and behavioural data from a loyalty card programme for the same individual. The total sample comprised n=30,696 Tesco shoppers. The online survey measured aspects of the in-store experience. These items were subjected to factor analysis to identify the influences on the in-store experience with four factors emerging: assortment, retail atmosphere, personalised customer service and checkout customer service. These factors were then matched for each individual with behavioural and demographic data collected via the Tesco Clubcard loyalty program. Regression and sensitivity analyses were then conducted to determine the relative impact of the in-store customer experience dimensions on customer behaviour. Findings include that perceptions of customer service have a strong positive impact on customers’ overall shopping satisfaction and spending behaviour. Perceptions of the in-store environment and product quality/ availability positively influence customer satisfaction but negatively influence the amount of money spent during their shopping trip. Furthermore, personalised customer service has a strong positive impact on spend and overall shopping satisfaction, which also positively influences the number of store visits the week after. However, an increase in shopping satisfaction coming from positive perceptions of the in-store environment and product quality/ availability factors helps to reduce their negative impact on spend week after. A key contribution of this study is to suggest a priority order for investment; retailers should prioritise personalised customer service and checkout customer service, followed by the in-store environment together with product quality and availability. These findings are very important in the context of the many initiatives the majority of retail operators undertake. Many retailers focus on cost-optimisation plans like implementing self-service check outs or easy to operate and clinical in-store environment. This research clearly and solidly shows which approach should be followed and what really matters for customers. That is why the findings are important for both retailers and academics, contributing to and expanding knowledge and practice on the impact of the in-store environment on the customer experience.
188

Multi-sensory cues in interplay and congruency in a retail store context : Consumer emotions and purchase behaviors

Helmefalk, Miralem January 2017 (has links)
While research has shown the positive impact of sensory cues and cue- congruency on emotion and behavior in retail store atmospheres, these cues have primarily been investigated in isolation or in pairs. Consequently, little is known on how multi-sensory cues in interplay impact on consumer emotions and purchase behaviors. In addition, research has not yet provided any clear conceptualization of congruency in marketing when designing retail store atmospheres, other than stating that some cues are expected to match, therefore become pleasantly perceived. Thus, the main purpose of this research is to examine and show how multi-sensory cues in interplay and congruency can be utilized in creating a retail store atmosphere to enhance consumer emotions and purchase behaviors. To address the purpose, a sequential method was adopted with four essays. The first essay explores multi-sensory interplay in marketing contexts with a literature review that forms the basis for a research agenda. The second essay employs focus groups to highlight the congruency between cues, products and the retail setting, and identifies which category of cues is in need of investigation. The third essay uses field experiments to investigate two congruent visual, auditory and olfactory cues (six cues in total) in a retail setting, and their impact on consumer emotion and purchase behavior. The final essay, also use field experiments to examine and duplicate one cue from each sense, and employs these together in interplay, to show how multi-sensory cues in interplay impacts emotions and purchase behaviors. This research concludes that multi-sensory cues in interplay in a retail store atmosphere have a greater impact on consumer emotions and purchase behaviors than single visual, auditory and olfactory setting-congruent sensory cues. Among single sensory cues, those perceived as complementary in the atmosphere, specifically auditory and olfactory in an already visual dominated atmosphere, have the largest impact on consumer emotions and purchase behaviors. Overall, this research signifies that congruent multi-sensory cues in interplay emerge as reliable predictors for the influence on consumer arousal, valence, time spent, touching, browsing and purchasing Theoretical and managerial implications are discussed.
189

Informell kommunikation, vad  spelar det egentligen för roll? : En fallstudie om informell kommunikation och kunskapsdelning på distans

Glimt Jensen, Gustav, Lindberg, Jacob January 2020 (has links)
Tidigare forskning har uttryckt stöd för den betydelsefulla roll informell kommunikation utgör för kunskapsdelning. Denna kommunikation äger till stor del rum i fysiska förhållanden, men vilka blir konsekvenserna när den förpassas till en digital miljö? Denna fallstudie undersöker hur den informella kommunikationen har kommit att se ut till följd av att företagets anställda arbetar på distans samt hur detta potentiellt kan ha kommit att påverka dess roll för kunskapsdelning inom organisationen. Med utgångspunkt i tidigare forskning utformades ett ramverk för att beskriva påverkanssambandet mellan distansarbete, informell kommunikation och kunskapsdelning. För att studera detta utfördes en fallstudie på ett e-handelsföretag, där sju intervjuer genomfördes och delar av en intern medarbetarundersökning granskades.Resultaten indikerar att förekomsten av informell kommunikation minskade samtidigt som den blev mer arbetsorienterad. Detta tycks ha haft negativa konsekvenser för den interna kunskapsdelningen då anställda ansåg sig ha sämre inblick i andra avdelningars arbete. Den försämrade insynen kan eventuellt innebära komplikationer för organisatorisk koordinering och nytänkande.
190

Making sense of the brand extension decision

Holmkvist, Jesper, Almerfors, Victor January 2021 (has links)
The purpose of this study is to utilize the sensemaking perspective to increase the understanding of what makes managers consider brand extensions, and how the decision is formed throughout the sensemaking process. The study aims to add to the existing literature by providing knowledge about the largely unexamined domain of managerial practice related to brand extensions. Furthermore, this study is designed as a qualitative multiple case study on four Swedish distilleries. The data was gathered primarily through semi-structured interviews and processed using a thematic method of analysis. This study found that brand extension decisions are influenced by managers subjective interpretive frameworks and previous organizational identity constructions. Contextual factors affects managers perceived need of brand extensions following the attention to one or more cues.

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