Abstract

Study of the temporal characteristics of the visual response requires the spatial variations to be taken into account. The spatial metric of human vision conforms to the ganglion-cell density as a function of eccentricity. Visual acuity, peak spatial frequency sensitivity, and the reciprocal of spatial integration area are all proportional to ganglion-cell density. The temporal metric, on the other hand, shows increasing temporal resolution with eccentricity. When equated for spatial characteristics, temporal resolution, peak temporal frequency sensitivity, and reciprocal integration time all increase by more than a factor of 2 from fovea to far periphery. This result holds for all luminance levels and applies to both cone and rod systems. At high luminance the peak time of the human impulse response may be as short as 20 ms in the far periphery, and it varies by a factor of 1.3 from the central fovea to 1° eccentricity. There is substantial evidence that the temporal and luminance adaptation characteristics for visual detection are determined in the outer segments of the photoreceptors. The dimensions of the outer segments are a possible source of the variation in time constant with eccentricity. The inhibitory component of the temporal response is entirely attributable to spatial lateral inhibition.

© 1985 Optical Society of America