In an experiment, biologists repeatedly shone a bright light into a tank containing a sea snail and simultaneously shook the tank  The snail invariably responded by tensing its muscular foot,  a typical reaction in sea snails to ocean turbulence  After several repetitions of this procedure, the snail tensed its foot whenever the biologists shone the light into its tank, even when the tank was not simultaneously shaken
Ttherefore, the snail must have learned to associate the shining of the bright light with the shaking of the tank
The appearance of a bright light alone would ordinarily not result in the sea snail's tensing its foot. 