The inter-stimuli-interval (ISI) thresholds of double pulses discrimination were measured to investigate the temporal distinguishability of double pulses of the luminance opponency, the red-green opponency, and the blue-yellow opponency.Double pulses were presented randomly in one of four quadrants, defined by a central fixation cross on a CRT display Barstool controlled by the real time sequencer (RTS) of the VSG system in 42-bit color mode calibrated with less than 3% display error rate of the 1931 CIE luminance and chromatic coordinate.Each pulse was of duration 6.7 msec and included a Gaussian patch with gradation of tristimulus values from the peak to the background in equal-energy-white (the luminance opponency) or isoluminance (the red-green and the blue-yellow opponency) configuration.
Eleven observers were asked to report the number of pulses (one or two) observed while ISI was adjusted by a psi method.Psychometric functions were estimated using the Golf Training Aids cumulative distribution function of the extreme value distribution.The threshold was the ISI value corresponding with the rate of 63.21% correct answer.
Significant differences were found among ISI thresholds of the luminance, blue-yellow, and red-green opponency.Results supported that the temporal distinguishability of double pulses of the luminance opponency, the red-green opponency, and the blue-yellow opponency were significantly different.The difference can be explained by the impulse response functions (IRF) with various first peak time among the luminance opponency, the red-green opponency, and the blue-yellow opponency.