abstract: Perceived heaviness of lifted objects has been shown to scale to a ratio of muscle activity and movement during elbow lifts. This scaling reflects the importance of the forces applied to an object and the resulting kinematics for this perception. The current study determined whether these perceived heaviness dynamics are similar in other lifting conditions. Anatomically sourced context-conditioned variability has implications for motor control. The current study investigated whether these implications also hold for heaviness perception. In two experiments participants lifted objects with knee extension lifts and with several arm lifts and reported perceived heaviness. The resulting psychophysiological functions revealed the hypothesized muscle activity and movement ratio in both leg and arms lifts. Further, principal component regressions showed that the forearm flexors and corresponding joint angular accelerations were most relevant for perceived heaviness during arm lifts. Perceived heaviness dynamics are similar in the arms and legs. / Dissertation/Thesis / Masters Thesis Psychology 2016

Current models of face perception suggest independent processing of identity and expression, though this distinction is still unclear. Using converging methods of psychophysics and functional magnetic resonance imaging (fMRI) in healthy and patient populations we assessed the relationship between these two perceptual processes. First, using perceptual aftereffects, we explored the neural representations underlying identity and expression. The expression aftereffect only partially transferred across different identities, suggesting adaptation within identity-invariant and identity-dependent expression representations. Contrarily, the identity aftereffect fully transferred across different expressions. This asymmetry cannot be explained through low-level adaptation. The identity-dependent component of the expression aftereffect relies on adaptation to a coherent expression, not low-level features, in the adapting face. Thus adaptation generating the expression aftereffect must occur within high-level representations of facial expression. Second, using fMRI adaptation, we examined identity and expression sensitivity in healthy controls. The fusiform face area and posterior superior temporal sulcus showed sensitivity for both identity and expression changes. Independent sensitivity for identity and expression changes was observed in the precuneus and middle superior temporal sulcus respectively. Finally, we explored identity and expression perception in a neuropsychological population. Selective identity impairments were associated with inferior occipitotemporal damage, not necessarily affecting the occipital or fusiform face areas. Impaired expression perception was associated with superior temporal sulcus damage, and also with deficits in the integration of identity and expression. In summary, psychophysics, neuroimaging and neuropsychological methods all provide converging evidence for the independent processing of identity and expression within the face network. However, these same methods also supply converging evidence for a partial dependence of these two perceptual processes: in the expression aftereffect, the functional sensitivities of the FFA and pSTS, and identity deficits observed in a patient with primarily impaired expression perception and a spared inferotemporal cortex. Thus, future models of face perception must incorporate representations or regions which independently process identity or expression as well as those which are involved in the perception of both identity and expression. / Medicine, Faculty of / Graduate

The present thesis constitutes an empirical investigation of the prediction of Norwich's Entropy Theory of Perception that the positive exponent of the magnitude estimation power function and the negative exponents of equations relating the Weber fraction and simple reaction time to stimulus intensity should, since they can all be derived from the theory's Fundamental Equation, be numerically the same. A pilot study consisting of magnitude estimation and reaction time experiments (using pure tone auditory stimuli of varying intensities at five frequencies), and a "main" study comprised of magnitude estimation, reaction time, and Weber fraction experiments are described. The results, while offering possible confirmation of the prediction, remain somewhat tentative, owing to the persistently problematic technique of curve fitting upon which determination of the reaction time and Weber fraction exponents rests. The theory, in leading one to even attempt to compare such previously unrelated measures as magnitude estimation and reaction time with Weber fractions, has yielded, theoretical issues aside, some worthwhile empirical results: I have obtained measures on three different psychophysical tasks from the same subjects over (effectively) the same stimulus range for each of those subjects; and, moreover have, I believe for the first time, explicitly noted that the Weber fraction displays the same decrease in exponent with increasing frequency, followed by an upturn at the highest frequencies, that characterizes both the equal loudness curves and the reaction time curves a la Chocholle. Suggestions are made regarding supplementary curve fitting methods by which to analyze these data, as well as for future research in the psychophysiological realm which, in addition to expanding the scope of the prediction that is being tested, may provide some much needed insight into the numerical values of the multiplicative and additive constants that occur in the equations under consideration in this thesis. / Arts, Faculty of / Psychology, Department of / Graduate

Echolocation is using lagging sounds as cues to localize the objects reflecting them. The precedence effect (PE) occurs when echoic signals are suppressed in favour of leading signals. In this study, the ability of nine listeners to overcome the PE when detecting and lateralizing echoic signals through headphones was measured and compared. Threshold estimates of the lead-lag ratio (dB) for lead-lag click-pairs at eight different inter-click intervals (ICIs) between 6-200ms were obtained. Further, two listeners trained each task at two ICIs (12 and 200ms) for seven days to investigate training, and transfer of training, effect between tasks. The results revealed that the PE is still present in lateralization tasks when ICI is at least 48ms. A threshold level difference between echo detection and lateralization was observed, indicating a possibility of different processing mechanisms between tasks. No training effects were found although longer training periods could provide more answers to what lies behind the ability to overcome the PE and echolocate efficiently in everyday life.

Yes / Two subdivisions of human V5/MT+; one located posteriorly (MT/TO-1), the other more anteriorly (MST/TO-2), were identified in human participants using functional magnetic resonance imaging (fMRI) on the basis of their representations of the ipsi- versus contra-lateral visual field. These subdivisions were then targeted for disruption by the application of repetitive transcranial magnetic stimulation (rTMS). rTMS was delivered to cortical areas whilst participants performed direction discrimination tasks involving three different types of moving stimuli defined by the translational, radial or rotational motion of dot patterns. For translational motion, performance was significantly reduced relative to baseline when rTMS was applied to both MT/TO-1 and MST/TO-2. For radial motion there was a differential effect between MT/TO-1 and MST/TO-2, with only disruption of the latter area affecting performance. rTMS failed to reveal a complete dissociation between MT/TO-1 and MST/TO-2 in terms of their contribution to the perception of rotational motion. On the basis of these results MT/TO-1 and MST/TO-2 appear to be functionally distinct subdivisions of hMT/V5+. Whilst both areas appear to be implicated in the processing of translational motion, only the anterior region (MST/TO-2) makes a causal contribution to the perception of radial motion. / BBSRC

Yes / We used triple silent substitution stimuli to characterize human S-cone electroretinograms (ERGs) in normal trichromats. Short-wavelength-cone (S-cone) ERGs were found to have different morphological features and temporal frequency response characteristics compared to ERGs derived from L-cones, M-cones, and rod photoreceptors in normal participants. Furthermore, in two cases of retinal pathology, blue cone monochromatism (BCM) and enhanced S-cone syndrome (ESCS), S-cone ERGs elicited by our stimuli were preserved and enhanced, respectively. The results from both normal and pathological retinae demonstrate that triple silent substitution stimuli can be used to generate ERGs that provide an assay of human S-cone function. / Deutsche Forschungsgemeinschaft (DFG) (KR1317/13-1); Bundesministerium für Bildung und Forschung (BMBF) (01DN14009)

Yes / Edge detection is widely believed to be an important early stage in human visual processing. However, there have been relatively few attempts to map human edge detection filters. In this study, observers had to locate a randomly placed step edge in brown noise (the integral of white noise) with a 1/𝑓2 power spectrum. Their responses were modelled by assuming the probability the observer chose an edge location depended on the response of their own edge detection filter to that location. The observer’s edge detection filter was then estimated by maximum likelihood methods. The filters obtained were odd-symmetric and similar to a derivative of Gaussian, with a peak-to-trough width of 0.1–0.15 degrees. These filters are compared with previous estimates of edge detectors in humans, and with neurophysiological receptive fields and theoretical edge detectors.

O objetivo geral deste estudo foi avaliar a dor crônica advinda de diferentes tipos de cânceres. Os objetivos específicos foram descrever as características sociais dos participantes, caracterizar a dor percebida por meio de indicadores específicos e identificar os 10 descritores de dor crônica de maior e menor atribuição conforme a percepção da amostra. Participaram do estudo 45 mulheres com câncer de mama, 45 homens com câncer de próstata e 60 indivíduos de ambos os sexos com câncer de sistema digestivo. Para a mensuração da dor foram utilizados os 50 descritores de dor crônica que compõem a Escala Multidimensional de Avaliação de Dor (EMADOR), utilizando-se o método psicofísico de estimação de categorias. Os resultados da caracterização social das 3 amostras foram: a média de idade foi de 60 anos, 54% eram do gênero masculino, 58,7% casados, 65,3% pertencentes à religião católica e 50,6% tinham ensino fundamental completo. Na caracterização da dor foi evidenciado que, referente ao sítio primário do tumor, 30% estavam localizados na mama, 30% na próstata e 14,7% no estômago. O início da queixa dolorosa ocorreu em 40,7% dos participantes antes do diagnóstico da doença, 52,7% relataram somente 1 sítio de dor e 55,4% relataram que a mesma era intermitente. A intensidade da dor atribuída nas 3 amostras, considerando a média aritmética, demonstrou que os participantes com tumores de sistema digestivo reportaram os maiores escores (7,58 ± 2,59) e 26,6% desta amostra relataram escores acima de 8 para todos os descritores apresentados. Na avaliação dos descritores 10 descritores de maior atribuição foi observado que, 5 estavam presentes nas 3 amostras: -dolorosa?, -desconfortável?, -chata?, -desagradável? e o descritor -incômoda?, o qual foi o mais atribuído tanto pelos participantes com câncer de sistema digestivo quanto pelos participantes com câncer de próstata, demonstrando a similaridade da linguagem da dor nos diferentes grupos. Sobre a dimensão dos descritores de maior atribuição nas 3 amostras houve predomínio de descritores de dor crônica que caracterizaram a dimensão afetiva (50%), seguido pelos de dimensão cognitiva (26,6%) e pelos de dimensão sensitiva (23,3%). Concluímos que, mesmo sendo a dor oncológica um fenômeno considerado individual, multidimensional com comprometimento em diversos domínios da vida, a sua linguagem apresenta semelhança independente do sítio do tumor e do gênero e a dimensão afetiva da dor deve ser melhor explorada nas avaliações clínicas. / The aim general of this study was to evaluate chronic pain arising from different types of cancers. The specific objectives were to describe the social characteristics of the participants, to characterize the pain perceived by specific indicators and descriptors to identify the 10 major and minor award chronic cancer pain as perceived in the sample. The study included 45 women with breast cancer, 45 men with prostate cancer and 60 individuals of both sexes with cancers of the digestive system. For the measurement of pain were used 50 descriptors of chronic pain comprising the Multidimensional Pain Evaluation Scale (EMADOR), using the psychophysical method of category estimation. The results of the social characterization of the 3 samples were mean age was 60 years, 54% were male, 58.7% married, 65.3% belonging to the Catholic area and 50.6% had completed elementary education as schooling. The characterization of pain was evident that, for the primary tumor site 30% were located in the breast, prostate 30% and 14.7% in the stomach. The onset of pain complaint occurred in 40.7% of the participants before the diagnosis of disease, 52.7% reported only one site of pain and 55.4% reported that it was intermittent. Pain intensity given in three samples, considering the arithmetic mean, showed that participants with tumors of the digestive system report higher scores (7.58 ± 2.59) and 26.6% of this sample reported scores above average in 8 arithmetic mean of all the descriptors presented. In the evaluation of the descriptors was seen observed that among the 10 descriptors with higher scores, five were present in three samples: \"painful,\" \"uncomfortable\", \"boring,\" \"unpleasant,\" and the descriptor \"incommode? that was the longer assigned by both the participants with cancer of the digestive system and by the participants with prostate cancer, demonstrating the similarity of the language of pain in different groups. The dimension of descriptors with higher scores in three groups, there was a predominance of chronic pain descriptors that characterize the affective dimension (50%), followed by the cognitive dimension (26.6%) and size sensitive (23.3%). We conclude that even though cancer pain phenomenon considered an individual, multidimensional impairment in several areas of life, their language has similarities regardless of tumor site and gender, and affective dimension of pain should be further explored in the clinical ratings.

Objetivo: Avaliar a Função de Sensibilidade ao Contraste de Luminância Espacial e Temporal, estudar o desenvolvimento destas funções, a contribuição das vias de processamento paralelo para as funções de Sensibilidade ao Contraste e seu respectivo desenvolvimento e, por fim, determinar valores normativos destas funções visando uma aplicabilidade clínica.Método A avaliação psicofísica de sensibilidade ao contraste de luminância espacial e temporal foi realizada em 112 sujeitos divididos em três grupos:GrupoI ( idade média =9,14±2,7 anos),Grupo II ( idade média=23,7 ± 3,4 anos) e Grupo III ( idade média=41,8± 5,5 anos) com o programa PSYCHO for Windows Versão 2.36 (Cambridge Research Systems, CRS-Ltd, UK) acoplado a um microcomputador PC XTC -600. . Os estímulos foram apresentados em um monitor Sony Triniton de 19 polegadas GFD420 (Sony Corporation, USA) com resolução espacial de 800X600 e resolução temporal de 69 Hz Os estímulos eram comandados pela placa gráfica VSG 2/4 (Cambridge Research Systems, CRS-Ltd, UK).Resultados A avaliação psicofísica para a sensibilidade ao contraste espacial e temporal mostraram que esta função já está desenvolvida e em pleno funcionamento em crianças (6 anos) ocorrendo um declínio para as frequências espaciais de 2,0cpg;8,3cpg e 14,5cpg para os grupos II e III.Para a frequência temporal de 2,5Hz o declínio ocorre nos Grupos II e III e para a frequência temporal de 5,0 Hz nas idades mais avançadas(GIII). Para o estudo da contribuição das vias de processamento paralelo (magnocelular e parvocelular) podemos notar uma maior sensibilidade ao contraste para decremento de luz do que para incremento de luz, porém não foi possível determinar a real contribuição dessas vias para a função de sensibilidade ao contraste. Conclusão Avaliamos com sucesso a Sensibilidade ao Contraste Espacial e Temporal para todas as faixas etárias e, assim, conseguimos ter acesso ao desenvolvimento desta função, entre as idades de 6 e 57 anos. Valores normativos para as tais funções foram estabelecidos por metodologia nãoparamétrica.. O estudo da contribuição das vias magnocelular e parvocelular não pode ser conclusivo, porém os achados mostraram uma maior sensibilidade para o decremente de luz o que corrobora com a literatura / Purpose: To analyze the spatial and temporal luminance contrast sensitivity function, to study the development of these functions, the contribution of the parallel processing pathways and to determine the normative values of these functions to order a clinical applicability normative. Methods the psychophysical evaluation of the spatial and temporal luminance contrast sensitivity was performed in 112 subjects divided into three groups: Group I (mean age =9.14±2.7 years), Group II (mean age=23.7 ± 3.4 years) and Group III (mean age=41.8± 5.5 years) with the PSYCHO for Windows Version 2.36 (Cambridge Research Systems, CRS-Ltd, UK) connect to the microcomputer PC XTC -600. The stimuli was showed in a monitor Sony Triniton de 19 inches GFD420 (Sony Corporation, USA) with spatial resolution of the 800X600 and temporal resolution of the 69 Hz. The stimuli was made by the graphics card VSG 2/4 (Cambridge Research Systems, CRS-Ltd, UK).Results The psychophysics evaluation to spatial and temporal contrast sensitivity showed that this function is already developed and full operation in children (6 years old) with a decline to spatial frequencies of 2.0cpg;8.3cpg and 14.5 cpg to the groups II and III. For the temporal frequency of 2.5Hz the decline occur to the groups II and III .and to the temporal frequency of 5.0 Hz the decline occur to the advantage ages(GIII). For the study of the parallel processing pathways (magnocellular e parvocellular) we can see bigger contrast sensitivity to decrement than to increment of light. It was not possible determine the real contribution of these pathways to the contrast sensitivity function. Conclusion We evaluated in a successful way the spatial and temporal contrast sensitivity to all age range and so we could access the development of this function between the ages from 6 to 57 years old. Normatives values to this function were established for non parametric methodology. The study of the contribution of the parvocellular and magnocellular pathways is not conclusive, but the results showed a bigger sensibility to decrement than to increment of light that was similar to the literature

Esta dissertação é o resultado de uma pesquisa na área de psicofísica para obtenção de uma modelagem da percepção visual de saliências em formas bidimensionais. Para que este objetivo fosse atingido, foi desenvolvido um experimento psicofísico executado através de um programa computacional, que apresenta aos indivíduos imagens de formas (ou contornos) bidimensionais com diversas características e saliências. O experimento é realizado em duas etapas, ambas com 16 indivíduos, e assim divididas devido as características das formas utilizadas. A primeira etapa é constituída de 30 imagens que apresentam formas mais prováveis de serem encontradas diariamente, além de apresentarem uma maior simetria e alongamento do que as 25 imagens que compõem a segunda etapa. Os resultados do experimento, ou seja, a freqüência de escolha das regiões das imagens pelos indivíduos, foram organizados através de histogramas polares para cada uma das 55 imagens, sendo este gerados por computador através de um programa por nós desenvolvido. As conclusões obtidas, quando efetuou-se uma comparação das regiões escolhidas pelos indivíduos com os conceitos sobre percepção de formas (basicamente a regra da \"boafigura\" dosprincípios de Gestalt), foram que as regiões escolhidas com mais freqüência não são necessariamente as \"boas regiões\". A fim de obtermos modelos da percepção de saliências de formas bidimensionais, ou seja, modelos que determinem as regiões escolhidas pelos indivíduos durante a realização do experimento psicofísico, foram desenvolvidos dois métodos de modelagem, sendo um relacionado com campos vetoriais e o outro com a entropia da curvatura das imagens apresentadas como estímulos aos indivíduos. Os resultados dos dois modelos foram comparados com os resultados práticos obtidos através do experimento psicofísico, a fim de obtermos uma análise da validade dos modelos. Através desta comparação foi possível concluir que, apesar dos modelos apresentarem uma representação quantitativa de algumas das etapas do processo percepção de saliências, outros valores de suas variáveis devem ser testados para que o processo de modelagem torne-se mais próximo do ideal. / This dissertation is the result of the a research in the area of psychophysics in order to obtain a modeling of the visual perception of saliences in form bidimensionais. In order to reach the target, an psychophysical experiment was developed which was done through the use of a computer programme. This programme presents to individuals images of bidimensional shapes (or outlines) with a variety of characterisitcs and saliences. The experiment is done in two phases, both of which with 16 individuals, and afterwards it is divided into the characteristics of the shapes which were used. The first phase consists of 30 images that present the most probable shapes which can be found easily every day. It also presents a bigger symmetry and elongation when compared to the 25 images which are part of the second phase. This second phase presents the shapes which are not so probable to be found everyday. The result of the experiment, that is the frequency of the choice of the regions of the images by the individuals, were organized through the use of polar histograms for each one of the 55 images. The histograms were generated by a computer which uses a programme developed by us. The conclusion obtained, when a comparison of the regions chooses by the individuals with the concepts about perception of forms (basically the rule of the \"good shape\" of the Gestalt principles), were that the regions choosen more frequently were not the \"good regions\". In order to obtain models of the perception of the saliences of the bidimensional shapes, which are the models that determine the regions chosen by the individuals during the psychophysical experiment, two methods of modeling were developed. One of them is related to vectorial fields and the other to the entropy of the curvature of the images presented as stimulus to the individuals. The results of the two models were compared to the practical results obtained through the psychophysical experiment in order to obtain an analisys of the validity of the models. Through this comparison was possible to conclude that \' although the models present a quantitative representation of some steps of the process of perception of saliencies, other values of its variables should be tested in order to mabe the process of modeling closer to the ideal one.