p542fig15.04 Conditioning data from (Smith 1968; Millenson etal 1977).  The former shows the kind of Weber Law and inverted U that were simulated in Figure 15.3.  The latter shows that, if there are two ISIs during an experiment, then the animals learn to adaptively time their responses with two properly scaled Weber laws.<BR>||  (left) One ISI (Smith 1968)  [mean membrane extension (mm) versus time after CS onset (msec)].  (right) Two ISIs (Millenson etal 1977) [200, 100] msec CS test trials, [mean momentary CS amplitude (mm) vs time after CS onset (msec)].  (bottom) Conditioned eye blinks, made with nictitating membrane and/or eyelid, are adaptively timed: peak closure occurs at expected time(s) of arrival of the US following the CS and obeys a Weber Law.