Spatial and temporal summation in the human dark-adapted retina.

A coherent set of absolute-threshold data is presented for circular flashes with a diameter of 5-343 min of arc, a flash duration of 32-1000 msec, and at eccentricities between 7 and 50 deg in the temporal retina. A reduction in the flash interval from 4 to 1 sec causes a threshold elevation for eccentricities exceeding 15 deg for all other stimulus parameters. It is shown that local adaptation affects the measurements significantly, especially when long-lasting stimuli and large eccentricities exist. The results can be described with the help of a quanta-coincidence model if adaptational properties are included.