On the Integrate Capacity in Time and Space of the Human Peripheral Retina

Abstract

Measurements of the chance of interaction for a light perception of two stimuli projected at various distances in time and place from each other in the dark-adapted human peripheral retina are presented. The two separate test stimuli were about 2′ of angular size and each lasted 0.01 second. The time ϓ between these two was varied from 0 to 0.21 second, the distance δ between them 0–25 minutes of arc. The chance of interaction was measured by determination of the chances of observation for each test stimulus apart and for ϓ=δ=0. The colors of the light from the separated stimuli were red and green, for red chiefly the cones being active and for green, the rods. In the study, one test stimulus activated the rods; in the other the cones were included. It proved that the chance for interaction is described by p(ϓ) · q(δ); P(ϓ) does not depend on the place on the retina used or on the kind of receptors stimulated by the two test flashes. q(δ) depends on the position of the retina and the kind of receptors concerned in agreement with the well-known facts of the validity of Ricco’s law. For mixed-rod cone vision q(δ) is situated intermediately between q(δ) for pure cone and pure rod vision on the position of the retina under consideration. Eccentricities from 5° up to 27° from the fovea are used. The results are discussed in relation to outstanding details of the two quanta explanation of the absolute thresholds.