Temporal summation and perimetry.

The threshold sensitivity at perimetry was determined experimentally as a function of the exposure time of the test objects. The summation capability of the retina is expressed as a 'memory' function with approximately exponential decay. The efficient stimulus is found from the convolution integral of the functions for memory and light stimulus. The effacing of relative defects by a prolonged exposure time is explained by means of a hypothetical model, based on the rarefaction of optic-nerve fibres.