IMPRINTING

in psychobiology, a form of learning in which a very young animal fixes its attention on the first object with which it has visual, auditory, or tactile experience and thereafter follows that object. In nature the object is almost invariably a parent; in experiments, other animals and inanimate objects have been used. Imprinting has been intensively studied only in birds, especially chickens, ducks, and geese, but a comparable form of learning apparently occurs in the young of many mammals and some fishes and insects. In mallard ducklings and domestic chicks, imprinting can be accomplished in a few hours, but receptivity to imprinting stimuli vanishes at the age of about 30 hours. process of transferring writing from a master copy to another form. There are three basic methods of imprinting: (1) spirit hectograph master cards, (2) stencil cards, and (3) metal or plastic plates. Hectograph master cards are made with the aid of hectograph carbon, with the imprint transferred by means of a chemical solution. Up to 250 imprints may be made from a single master card. Stencil cards consist of small pieces of stencil tissue mounted in a cardboard frame. The copy to be imprinted is on the stencil tissue. Metal or plastic plates of various sizes may be embossed, with the text standing out in relief, on a special machine. Forms or envelopes are imprinted through an inked ribbon as the raised-image plates are fed through another machine, which operates automatically at high speed. The plates are practically indestructible.