  The mechanism of negative group delay (NGD) is used to understand the
anticipatory capability of a retina. Experiments with retinas from bull frogs
are performed to compare with the predictions of the NGD model. In particulars,
whole field stochastic stimulation with various time correlations are used to
probe anticipatory responses from the retina. We find that the NGD model can
reproduce essential features of experimental observations characterized by the
cross correlations between the stimulation and the retinal responses. The
prediction horizon of a retina is found to depend on the correlation time of
the stimulation as predicted by the NGD model. Experiments with dark and bright
Gaussian light pulses further support the NGD mechanism; but only for the dark
pulses indicating that the NGD effect of a retina might originate from its OFF
response. Our finding suggests that sensory systems capable of using negative
feedback for adaptation can give rise to anticipation as a consequence of the
delay in the system.
