
Biology 101 invades Art History 407. The canary graduates, with flying colors.
PITY THE SEA SLUG APLYSIA, famous in biological circles for its predictability, manipulability, and naiveté. Poke an Aplysia in the side and it’ll withdraw its gill (whether in terror or in pique, it’s impossible to say); poke it every twenty seconds or so for several minutes and the animal, on to the game, stops cringing. Now pat it just once on its little head or its little flipper—a new stimulus—and you’ll find the gill-withdrawal reflex is back in full force. Biologists call this phenomenon habituation. As sensory experiences go, habituation is fairly complex, believed to involve not only