Preenchimento perceptual em tricromatas e dicromatas

AUTOR(ES)

Márcia Furukawa Couto

DATA DE PUBLICAÇÃO

2006

RESUMO

Introduction: A stationary object at the peripheral visual field disappears after a few seconds of fixation. This phenomenon, known as Troxlers effect, is attributed to perceptual filling-in. The filling-in latency is influenced by the image characteristics (object size and stability, eccentricity, borders, color and brightness). The purposes of this investigation are: (i) to evaluate the influence of different visual parameters on the perceptual filling-in latency; and (ii) to compare filling-in results between trichromats and dichromats. Methods: Altogether there were three experiments with filling-in targets as follows: (i) the first one was gray; (ii) the second one was stereoscopic; and (iii) the third one was colored for blue/yellow, red/green and achromatic opponent channels, tested at two eccentricities. In all the experiments the filling-in was tested at different visual field positions. Results: Both trichromats and dichromats showed a longer filling-in latency for the following visual field positions: (i) horizontal as compared to vertical; (ii) inferior as compared to superior. There was no filling-in difference when the stereoscopic positions were changed. Trichromats presented higher center to periphery decline for blue/yellow and achromatic than red/green opponent channels, contrary to their retinotopic characteristics. Dichromats presented a nonsignificant center to periphery filling-in latency decline for the blue/yellow channel. Conclusions: (i) the objects visual field position strongly influences the filling-in latency; (ii) there is no influence of the objects three-dimensional space position on the filling-in latency with the disparity values tested; (iii) trichromats presented influence of nonretinotopic cortical areas on the color filling-in; and (iv) the dichromats only color opponency channel (blue/yellow) is more evenly distributed throughout the visual field than the trichromats.

ASSUNTO(S)

preenchimento perceptual canal de oponência estereoscopia tricromata campo visual dicromata neurofisiologia

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