Yes / Background: Descending kerbs during locomotion involves the regulation of appropriate foot placement before the kerb-edge and foot clearance over it. It also involves the modulation of gait output to ensure the body-mass is safely and smoothly lowered to the new level. Previous research has shown that vision is used in such adaptive gait tasks for feedforward planning, with vision from the lower visual field (lvf) used for online updating. The present study determined when lvf information is used to control/update locomotion when stepping from a kerb. Methodology/Principal Findings: 12 young adults stepped down a kerb during ongoing gait. Force sensitive resistors (attached to participants' feet) interfaced with an high-speed PDLC 'smart glass' sheet, allowed the lvf to be unpredictably occluded at either heel-contact of the penultimate or final step before the kerb-edge up to contact with the lower level. Analysis focussed on determining changes in foot placement distance before the kerb-edge, clearance over it, and in kinematic measures of the step down. Lvf occlusion from the instant of final step contact had no significant effect on any dependant variable (p>0.09). Occlusion of the lvf from the instant of penultimate step contact had a significant effect on foot clearance and on several kinematic measures, with findings consistent with participants becoming uncertain regarding relative horizontal location of the kerb-edge. Conclusion/Significance: These findings suggest concurrent feedback of the lower limb, kerb-edge, and/or floor area immediately in front/below the kerb is not used when stepping from a kerb during ongoing gait. Instead heel-clearance and pre-landing-kinematic parameters are determined/planned using lvf information acquired in the penultimate step during the approach to the kerb-edge, with information related to foot placement before the kerb-edge being the most salient.

It has been shown that infants build representations of their visual world by forming relations among its parts. However little is known about how they select the parts to relate. One possibility is that while constructing their visual world part by part they are also decomposing it, using finer and finer parts. One way to test this theory is to simply control the parts infants see. This easiest way to do this is to filter real life objects of their high and low spatial frequencies. High spatial frequencies provide information about the smaller parts where as low spatial frequencies provide information about the larger ones. By removing high or low spatial frequency we can control the coarseness of their representation and ultimately determine the level at which they function best. The present study examined infants’ ability to use high and low spatial frequencies to discriminate between objects. Infants were habituated and tested using a combination of high and low spatial frequency images. Only infants experiencing a consistent spatial frequency across habituation and test were able to discriminate between objects. Infants were also better at discriminating between objects containing high spatial frequencies. In a second study designed to be more true to life, infants were habituated to broadband images and tested using high or low spatial frequencies. This time infants did not discriminate between objects but they did look longer at low spatial frequency information than at the high. From these findings we can conclude that infants use both high and low spatial frequency information when discriminating objects, and that in certain cases one frequency may become more important than the other. The spatial frequency they use may be dependent on the context of the task. Numerous studies have shown that adults prioritize high and low spatial frequency information depending on how fast they want to process the object, the amount of detail they require, and whether they used high or low spatial frequency information during previous experiences. Infants may be similar. At times they may emphasize low spatial frequency information and the big picture. At other times they may emphasize high spatial frequency information and the detail. More studies examining how infants select information for processing are necessary and spatial frequency will likely to be an important tool in the investigation. / text

Gender is among the most influential of the factors underlying differences in spatial abilities, human communication and interactions with and through computers. Past research has offered important insights into gender differences in navigation and language use. Yet, given the multidimensionality of these domains, many issues remain contentious while others unexplored. Moreover, having been derived from non-interactive, and often artificial, studies, the generalisability of this research to interactive contexts of use, particularly in the practical domain of Human-Computer Interaction (HCI), may be problematic. At the same time, little is known about how gender strategies, behaviours and preferences interact with the features of technology in various domains of HCI, including collaborative systems and systems with natural language interfaces. Targeting these knowledge gaps, the thesis aims to address the central question of how gender differences emerge and operate in spatial navigation dialogues with computer systems. To this end, an empirical study is undertaken, in which, mixed-gender and same-gender pairs communicate to complete an urban navigation task, with one of the participants being under the impression that he/she interacts with a robot. Performance and dialogue data were collected using a custom system that supported synchronous navigation and communication between the user and the robot. Based on this empirical data, the thesis describes the key role of the interaction of gender in navigation performance and communication processes, which outweighed the effect of individual gender, moderating gender differences and reversing predicted patterns of performance and language use. This thesis has produced several contributions; theoretical, methodological and practical. From a theoretical perspective, it offers novel findings in gender differences in navigation and communication. The methodological contribution concerns the successful application of dialogue as a naturalistic, and yet experimentally sound, research paradigm to study gender and spatial language. The practical contributions include concrete design guidelines for natural language systems and implications for the development of gender-neutral interfaces in specific domains of HCI.

In spite of technological advances in wireless systems, transmitted data suffers from impairments through both lossy source coding and transmission overerror prone channels. Due to these errors, the quality of multimedia content is degraded. The major challenge for service providers in this scenario is to measure the perceptual impact of distortions to provide certain Quality of Experience(QoE) to the end user. The general tendency of the Human Visual System (HVS) suggests that the artifacts in the Region-of-Interest (ROI) are perceived to be more annoying compared to the artifacts in Background (BG). With this assumption, the thesis aims to measure the quality of image over ROI and BG independently. Visual Information Fidelity (VIF), a full-reference image quality assessment is chosen for this purpose. Finally, the metric measured over ROI and BG are pooled to get a ROI aware metric. The ROI aware metric is used to predict the Mean Opinion Score (MOS) of an image. In this study, an ROI aware quality metric is used to measure the quality of a set of distorted images generated using a wireless channel. Eventually, MOS of the distorted images is estimated. Lastly, the predicted MOS is validated with the MOS obtained from subjective tests. Testing the proposed image quality assessment approach shows an improved prediction performance of ROI aware quality metric over traditional image quality metrics. It is also observed that the above approach provides a consistent improvement over a wide variety of distortions. After extensive research, the obtained results suggest that the impairments in the ROI are perceived to be more annoying than that of the BG.

Orientador: Edberto Ferneda / Banca: Guilherme de Ataíde Dias / Banca: Silvana Aparecida Borseti Gregório Vidotti / Resumo: O advento da Web e o conseqüente aumento no volume de informações eletrônicas acarretaram muitos problemas em relação ao acesso, busca, localização e recuperação de informação em grandes volumes de dados. O presente trabalho realiza uma revisão dos diferentes modelos, métodos e algoritmos existentes para a geração de Interfaces Visuais para Recuperação da Informação, classificados segundo ao seu processo de produção: Análise e Transformação dos Dados, Aplicação de Algoritmos de Classificação e Distribuição Visual e Aplicação de Técnicas de Transformação Visual. Os resultados pretendem servir a outros investigadores como ferramenta para a eleição de uma ou outra combinação metodológica no desenvolvimento de propostas específicas de Interfaces Visuais para Recuperação da Informação, além de sugerir a necessidade de maiores investigações sobre novas técnicas de transformação visual. / Abstract: The advent of the Web and the consequent increase in the volume of electronic information had caused many problems about access, search, location and retrieval of information in large volumes of data. This work is a revision of the different models, methods and algorithms to create interfaces for Visual Information Retrieval, classified according to their production process: Analysis and Data Processing, Implementation of algorithms for classification and distribution of Visual and Application Processing Techniques of Visual. The results of other researchers want to serve as a tool for the election of one or another combination methodology in the development of specific proposals for visual interfaces for information retrieval, and suggest the need for more research into new techniques for processing visual. / Mestre

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-05-23T18:04:12Z No. of bitstreams: 1 RegisCostaOliveira.pdf: 2442139 bytes, checksum: 9d55d79bf14ea8419cb9d60c93f3aff8 (MD5) / Made available in DSpace on 2017-05-23T18:04:12Z (GMT). No. of bitstreams: 1 RegisCostaOliveira.pdf: 2442139 bytes, checksum: 9d55d79bf14ea8419cb9d60c93f3aff8 (MD5) Previous issue date: 2016-06-03 / The imagistic reading in visual arts classes, usually occurs from a Eurocentric tradition acquis which is strange to much of the student visuality and the curatorial process intermediated by the teacher. Given these characteristics, it is imperative to think of new methodological procedures for the practice of reading images. Thus, this article analyzes the application of the project Image and Memory in Visual Arts classes at the Federal Institute of Maranhão, Buriticupu campus to the practice of imagistic reading from the curatorial model present at the Mnemosyne Atlas by Aby Warburg and the archeology image recommended in the studies of Georges Didi-Huberman, in order to place the student as the protagonist of the curation process visual information, from his visuality and weaving the threads that articulate images from mnemonics and conceptual aspects. / A leitura imagética, nas aulas de Artes Visuais, geralmente ocorre a partir de um acervo de tradição eurocêntrica, estranho a grande parte das visualidades dos alunos e com o processo curatorial protagonizado pelo docente. Frente a estas características, torna-se imperativo pensar em novos processos metodológicos para a prática da leitura de imagens. Dessa forma, o presente artigo analisa a aplicação do projeto Imagem e Memória nas aulas de Artes Visuais do Instituto Federal do Maranhão, campus Buriticupu, para a prática da leitura imagética a partir do modelo de curadoria presente no Atlas Mnemosyne de Aby Warburg e da arqueologia da imagem preconizada nos estudos de Georges Didi-Huberman, com o intuito de situar o aluno como protagonista do processo de curadoria da informação visual, partindo de sua visualidade e tecendo as tramas que articularão as imagens a partir de aspectos mnemônicos e conceituais.

The aim of this field study was to investigate the relationship between visual information processing skills of Australian Capital Territory Year 1 1 and 12 T mathematics students and their capabilities in interpreting information presented in graphical form. A random sample of 37 T mathematics classes, comprising 621 Year 11 and 12 students were tested for their ability to interpret graphical information presented in two contexts. The first entailed the context provided by standard mathematics questions as seen in recent Australian mathematics student texts; the second context required students to transfer their visual information processing skills to situations unfamiliar to them, but requiring similar interpretive skills to the first context.

The aim of this thesis was to investigate how visual information is organised in perceptual short term memory, with special interest in colour, spatial frequency and velocity. Previous studies of VSTM have indicated the existence of specific memory mechanisms for visual attributes such as orientation, spatial frequency, velocity, contrast and colour. The retention of information in visual short term memory for these basic visual attributes can be disrupted by the presentation of masking stimuli during inter-stimulus intervals (ISIs), which are outside the range of traditional sensory masking. We exploited this memory masking effect in order to examine the organisation of visual information in VSTM. Four groups of experiments were conducted in which participants carried out a delayed discrimination paradigm that employed a two-alternative forced choice (2-AFC) procedure in conjunction with a method of constant stimuli. The fidelity of VSTM was measured by performance markers such as discrimination thresholds and point of subjective equalities. We have found selective memory masking effects, which serve as further evidence in favour of the modular organisation in VSTM, namely, that human visual perceptual memory is based upon multiple, tuned channels in case of colour, spatial frequency and speed, similar to those found in the earliest stages of visual processing for spatial frequency. Moreover, each of these storage mechanisms are tuned to a relatively narrow range of stimulus parameters that are closely linked to visual discrimination mechanisms. These findings add further support to the view that low-level sensory processing mechanisms form the basis for the retention of colour, spatial frequency and velocity information in perceptual memory. We also found evidence for the broad range of transfer of memory masking effects across spatial location, which indicates more long range, long duration interactions between channels that are likely to rely upon contributions from neural processes located in higher visual areas. In conclusion, the experiments presented in this thesis provide significant insight into the organization of visual information in perceptual short term memory.

This thesis explores methods for enhancing digital image-like sensations which might be similar to those experienced by blind users of electronic visual prostheses. Visual prostheses, otherwise referred to as artificial vision systems or bionic eyes, may operate at ultra low image quality and information levels as opposed to more common electronic displays such as televisions, for which our expectations of image quality are much higher. The scope of the research is limited to enhancement by digital image processing: that is, by manipulating the content of images presented to the user. The work was undertaken to improve the effectiveness of visual prostheses in representing the visible world. Presently visual prosthesis development is limited to animal models in Australia and prototype human trials overseas. Consequently this thesis deals with simulated vision experiments using normally sighted viewers. The experiments involve an original application of existing image processing techniques to the field of low quality vision anticipated from visual prostheses. Resulting from this work are firstly recommendations for effective image processing methods for enhancing viewer perception when using visual prosthesis prototypes. Although limited to low quality images, recognition of some objects can still be achieved, and it is useful for a viewer to be presented with several variations of the image representing different processing methods. Scene understanding can be improved by incorporating Region-of-Interest techniques that identify salient areas within images and allow a user to zoom into that area of the image. Also there is some benefit in tailoring the image processing depending on the type of scene. Secondly the research involved the construction of a metric for basic information required for the interpretation of a visual scene at low image quality. The amount of information content within an image was quantified using inherent attributes of the image and shown to be positively correlated with the ability of the image to be recognised at low quality.

Orientador: José Angelo Barela / Banca: Sérgio Tosi Rodrigues / Banca: Ronald Dennis Paul Kenneth Clive Ranvaud / Banca: Renato de Moraes / Banca: Dora S. Fix Ventura / Resumo: Três experimentos foram propostos para investigar os ajustes dinâmicos nos pesos de múltiplas fontes de informação sensorial. O primeiro experimento investigou as respostas posturais de 18 bebês frente às mudanças abruptas na amplitude do estímulo visual. Eles permaneceram sentados dentro de uma sala móvel por 8 tentativas de 60 segundos cada. A sala ficou estacionária na primeira tentativa. Nas sete tentativas seguintes, a sala foi oscilada em 0,2 Hz com amplitude de 1,1 cm, com exceção da quinta tentativa, na qual a sala foi movimentada em amplitude mais alta (3,2 cm). Os resultados mostraram fraco acoplamento entre informação visual e oscilação corporal. Contudo, a variabilidade de oscilação foi maior em bebês experientes no sentar independente. Nós concluímos que bebês não foram capazes de se adaptar às pequenas alterações na amplitude do estímulo visual. O segundo experimento investigou como o controle postural de crianças se adapta às abruptas mudanças no ambiente visual. Trinta crianças de 4, 8 e 12 anos de idade e dez adultos, permaneceram em pé dentro de uma sala móvel. A situação experimental foi similar a do primeiro experimento exceto que a amplitude baixa da sala foi de 0,5 cm e a amplitude alta foi de 3,2 cm. As respostas posturais de crianças mais velhas e adultas diminuíram mais para o estímulo visual do que aquelas de crianças mais novas quando a amplitude da sala foi aumentada. A variabilidade de oscilação diminuiu com a idade e foi maior durante a tentativa de alta amplitude. Crianças tão novas quanto 4 anos de idade já têm desenvolvida a capacidade de rapidamente diminuir a influência do estimulo visual. Contudo, os mais altos valores de ganho e variabilidade residual para crianças de 4 e 8 anos de idade sugerem que elas não apresentam respostas totalmente calibradas ao nível adulto... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Three experiments were designed to investigate the dynamic adjustments in the weights of multiple sensory modalities. The first experiment investigated the postural responses of 18 infants to abrupt changes in the amplitude of visual stimulus. They seated inside of a moving room for eight trials of 60 sec apiece. The room was stationary in the first trial. In the following seven trials, the room oscillated at 0.2 Hz with amplitude of 1.1 cm, with the exception of the fifth trial, in which the room moved at higher amplitude (3.2 cm). The results showed weak coupling between visual stimulus and body sway. However, sway variability of experienced sitters was higher in the high-amplitude trial. We concluded that infants were not able to adapt to low range of visual stimulus amplitude. The second experiment investigated how children’s postural control adapt to abrupt changes in the surrounding visual environment. Thirty children from 4-, 8- and 12-year olds and ten adults stood upright inside of a moving room. The experimental set-up was similar to the first experiment except that low-amplitude was 0.5 cm and high-amplitude was 3.2 cm. Body sway responses of old children and adults downweight more to the visual stimulus than young children when the amplitude of the room increased. Sway variability decreased with age and was largest during the high-amplitude trial. Children as young as four years of age have already developed the adaptive capability to quickly downweight visual information. However, the higher gain values and residual variability observed for the 4 and 8 year-old children suggest that they have not fully calibrated their response to the adult level. The third experiment investigated the postural responses of two sensory modalities measured simultaneously... (Complete abstract click electronic access below) / Doutor