ILAV   21219
INSTITUTO DE INVESTIGACION EN LUZ, AMBIENTE Y VISION
Unidad Ejecutora - UE
artículos
Título:
The influence of luminance contrast and chromatic contrast on reaction times to a stimulus
Autor/es:
O´DONELL, BEATRIZ; COLOMBO, ELISA M.
Revista:
International Journal of Lighting Research and Technology
Editorial:
CIBSE
Referencias:
Lugar: London; Año: 2008 vol. 40 p. 359 - 371
ISSN:
1365-7828
Resumen:
This paper investigates the influence of colour on the reaction time (RT) for a detection task where there are differences in luminance contrast and chromatic contrast. The results confirm that RTs are determined by a cone-opponent mechanism: RTs generated in response to S-cone isolating stimuli –blue-yellow channel- are the longest, whereas the shortest RTs are generated by L-M-cone isolating stimuli -red-green channel-. In addition, an asymmetry between ON and OFF opponent channels was observed when the stimuli were modulated on the blue-yellow channel. RTs results were reasonably well fitted to a Lorentz’s axial symmetry equation with parameters that can be interpreted in terms of the visual processing involved. When the stimulus and the background were matched photometrically in luminance, the isoluminant condition, and near this condition, RTs were determined by hue and chromatic contrast. RTs were found to decrease as luminance contrast is increased. For luminance contrasts of approximately 15% to 20%, RTs became closer to the RTs corresponding of the achromatic stimulus, thus becoming independent of colour for further luminance contrast increases. This asymptotic value of RT was reached for lower luminance contrasts as colour contrast was increased.