Search results for "Contrast"
showing 10 items of 1162 documents
Regression of benign hepatic lesions associated with exogenous estrogens withdrawal
2014
Learning objectives Background Findings and procedure details Conclusion Personal information References
Color stimuli perception in presence of light scattering.
2006
Perception of different color contrast stimuli was studied in the presence of light scattering: in a fog chamber in Clermont-Ferrand and in laboratory conditions where light scattering of similar levels was obtained, using different light scattering eye occluders. Blue (shortest wavelength) light is scattered in fog to the greatest extent, causing deterioration of vision quality especially for the monochromatic blue stimuli. However, for the color stimuli presented on a white background, visual acuity in fog for blue Landolt-C optotypes was higher than for red and green optotypes on the white background. The luminance of color Landolt-C optotypes presented on a LCD screen was chosen corresp…
Gender differences in implicit and explicit anxiety measures
2004
Abstract Explicit measures assess introspectively accessible self-descriptions and evaluations. In contrast, implicit measures assess introspectively inaccessible processes that operate outside of awareness. While women consistently yield higher scores on explicit anxiety measures, there are to date no studies available that examine gender differences in implicit anxiety measures. To analyse this topic, we used the Implicit Association Test (Study 1, N =248) and the Emotional Stroop task (Study 2, N =121) as implicit anxiety measures and a standard trait questionnaire as explicit anxiety measure. As expected, women scored higher on the explicit anxiety test. Women also yielded higher anxiet…
Thinking about anxiety moderates the relationship between implicit and explicit anxiety measures
2008
Abstract Explicit measures (e.g., questionnaires) assess introspectively accessible self-descriptions and evaluations. In contrast, implicit measures (e.g., the Implicit Association Test) assess the self-concept indirectly, usually by means of performance measures such as reaction-time tasks. Correlations between implicit and explicit measures of personality dispositions tend to be low. The current study ( N = 82) tested the hypothesis that thinking about anxiety-arousing (vs. extraversion-arousing) situations moderates the relationship between implicit and explicit anxiety measures. Results supported this prediction: While no association between implicit and explicit anxiety measures was …
Contrast sensitivity perimetry tests along the cardinal directions in color space: Correlation with the properties of the neural mechanisms mediating…
2014
It is well-known the advantages of measuring chromatic and achromatic contrast sensitivity for detecting pathologies. But these measurements are rarely used in clinical practice, due the complexity of the measurements and the examinator specialization. In fact, there is not a complete characterization of the response of the visual pathways to achromatic and chromatic spatio-temporal frequency stimuli. We have designed a new experimental device that facilitates these measurements and allow us to characterize the visual response in healthy patients. In this paper, we evaluated the responses of the visual pathways in healthy patients.
2015
The combination of local orientation collinearity and spatial frequency contrast in contour integration was studied in two experiments using a 2AFC contour detection and discrimination task. Target contours were defined by local orientation collinearity, spatial frequency contrast between contour and background elements, or both cues. Experiments differed in the source of spatial frequency contrast by manipulating the spatial frequency of either contour or background elements. Cue summation gains, defined as the performance benefit of double cue conditions over single cue conditions, were evaluated and tested against the predictions derived from probability summation and linear summation. S…
Howard–Dolman stereovision test at different opponent colour stimuli
2011
The purpose of this study was to investigate visual depth perception of real physical colour stimuli with red-green and blue-yellow opponency. We modified the Howard–Dolman stereotest where subjects should determine the closer of two bars emitting the light of definite colour placed in front of a CRT monitor served as colour background. Two-alternative forced-choice paradigms were used to determine depth perception threshold values. Thresholds close to 5–10 arcsec for luminance and colour contrast stimuli were revealed both for red-green and blue-yellow stimuli. A term, stereosensitivity – a reciprocal magnitude of the stereothreshold – was introduced to separately analyse luminance and col…
Spatio-temporal Contrast Sensitivity in the Cardinal Directions of the Colour Space. A Review
2010
AbstractWe review the psychophysics of the spatio-temporal contrast sensitivity in the cardinal directions of the colour space and their correlation with those neural characteristics of the visual system that limit the ability to perform contrast detection or pattern-resolution tasks. We focus our attention particularly on the influence of luminance level, spatial extent and spatial location of the stimuli - factors that determine the characteristics of the physiological mechanisms underlying detection. Optical factors do obviously play a role, but we will refer to them only briefly. Contrast sensitivity measurements are often used in clinical practice as a method to detect, at their early …
La eficacia del aprendizaje perceptual como tratamiento de la ambliopía en la infancia, frente a otros tratamientos convencionales
2019
La ambliopía es un trastorno asociado con respuestas anormales del ojo afectado en la corteza visual (Mansouri, Thompson y Hess, 2008) que reduce la agudeza visual (AV) y afecta la percepción espacial de objetos y movimientos. La oclusión, que cubre el ojo dominante, es el tratamiento clásico. El aprendizaje perceptivo ha mostrado resultados positivos, pero se necesitan más estudios a nivel visuo perceptivo, psicomotor y psicoeducativo. Objetivo Analizar el efecto del tratamiento en niños de 4 a 12 años de edad, en términos de AV, estereopsis, sensibilidad de contraste (CS), habilidades visuales-perceptuales, psicomotores y aspectos psicosociales y escolares. Los tratamientos estudiados son…
Apprendimento del tedesco: nuovi approcci nel training della pronuncia sotto il profilo della learner identity
2019
Utilizzare la propria voce fa parte dell’espressione dell’identità personale. Colui che intraprende lo studio di una lingua straniera si trova talora difronte alla difficoltà di articolare suoni e strutture prosodiche differenti dalla sua lingua nativa e altresì lontani dal proprio vissuto: strani ed estranei. Inoltre pregiudizi ricorrenti possono inibire l’attitudine dell’apprendente nei confronti della lingua che sta imparando. Questo contributo propone nuovi approcci alla lingua tedesca orale, diversi da quelli offerti dai libri di testo in uso nelle scuole italiane. Essi partono dal suono della lingua nella sua interezza e tengono conto di ritmo, struttura sillabica e sforzo articolator…