Increment threshold and detection latency in the rod and cone systems.

It was reported previously that increment-threshold functions obtained in the dark-adapted rod and cone systems have two distinct branches, and that these functions are predicted by a simple model similar to those developed to describe vertebrate reaptor responses. The model also makes several unusual predictions concerning the latency for detection of the increment field at threshold. These predictions were tested by measuring simple reaction time for detection of the increment field as function of background intensity. for background durations of 50 and 500 msec. The predictions were found to hold with reasonable accuracy for both the rod and cone systems.