We analyzed sustaining fiber responses in the crayfish visual system to light pulses using information processing techniques. The light pulse stimuli elicited a transient and a steady-state component in the EPSP input and in the firing rate of the spike train output. The overall information transfer of the system was very low (10^-4), with a sharp increase during the transient portion of the response followed by a steady decrease. The change in the information transfer rate is related to the difference in communication rates possible in spike trains with varying rates. This analysis corroborates the observed light reflex behavior.