Navegando por Assunto "Visual evaluation"
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Item Acesso aberto (Open Access) Opencards: uma nova proposta de ferramenta para estimava de limiares psicofísicos(Universidade Federal do Pará, 2017-01-27) CAMPOS, Yuri Sobral; GOULART, Paulo Roney Kilpp; http://lattes.cnpq.br/7800966999068746; SOUZA, Givago da Silva; http://lattes.cnpq.br/5705421011644718; https://orcid.org/0000-0002-4525-3971The knowledge the value of psychophysical thresholds is essential for any sensory study. In order to define a threshold value, before knowing the limits of sensitivity and the results are produced with the same, it is necessary a use of methodologies and tests to obtain them. Currently, it is comprehensive and use of computerized and non-computerized tests for a visual evaluation, however, the standards of advantages and disadvantages. In general, all tests are done with methodologies around you. The present study proposes the development of a printed test for a visual evaluation of discrimination. For this was sought a product of easy portability and application. The OpenCards consists of a set of boards printed in high spatial resolution and high color quality. On the plates with a mosaic of randomly colored circles within 16 color options with a target that differs from the background by a luminance difference. Targets have a shape of square, triangle, circle and letter X. Targets differed from the background by 90%, 80%, 70%, 60%, 50%, 40%, 35%, 35%, 30%, 25% , 20%, 15%, 10%, 5% of luminance contrast. There was still no sign without the target. To show the use of the OpenCards two methods of application have been elaborated. The first method was performed in an environment with controlled lighting and standard for studies in visual system. Plates were shown in subjects in random order and a task of the subject to identify a shape of the object. The subject's response was recorded and the procedure repeated 8 times. The second method was performed in an ambient light environment. The experimenter showed the plates with the same target ordered in descending contrast and how they shuffled along with a blank plate and asked the subject tested how to order in decreasing contrasts using a higher contrast plate as a reference. The test was performed with all two-stroke sets. The response of the subject tested was recorded in both methods applied and a taxon of subject was adjusted to a Gaussian model for an estimate of the psychophysical threshold. The threshold was the value of the luminance contrast in which the Gaussian model estimated the accuracy of 50% accuracy for the first applied method and 75% for the second applied method. Eight subjects were evaluated in both methods and three subjects. The estimated average threshold with the first method was 23.5 ± 3 and the mean estimated method with the second method was 30.1 ± 6.5. The mean difference between the results obtained by the two methods was 7.3% ± 3. The statistical difference between the thresholds estimated by two methods (p <0.05). Since the following stations are to be used for different types of work, and especially for them, they are applied in each method. OpenCards proved to be easy to apply by the experimenter, portability and understanding of the task by the subject tested.