Behavioral determination of critical flicker fusion in dogs.

Steady-state critical flicker-fusion frequencies (CFFs) were determined for four beagle dogs using the psychophysical technique of conditioned suppression. The CFFs obtained demonstrated that the dog can discriminate flicker at much faster rates than has been suggested by ERG data. In addition, dog rods may support the discrimination of flicker at much higher rates than can human rods. An indication of a psychophysical rod-cone break occurred at a luminance level intermediate to those previously reported in ERG CFF studies. This level is similar to that in the cat, but much higher than that in man. The high CFFs provide the first psychophysical evidence of a well-developed functioning cone system in the dog.