The influence of "preparedness" on autoshaping, schedule performance, and choice

Two groups of experimentally naive pigeons were exposed to an autoshaping procedure in which the response key was mounted on the wall (the conventional location) or on the floor of the chamber. In two experiments, subjects readily responded to the wall key, but floor-key subjects required shaping. A subsequent experiment compared performance of wall- and floor-key groups on an ascending series of fixed-ratio schedule values, resistance to extinction, differential reinforcement of other behavior, and reversal of key assignment. Each experiment was followed by several sessions of fixed-ratio training; the performance of the wall- and floor-key groups was almost identical throughout. In the final experiment, a fixed-ratio requirement could be completed on either or both keys. Birds initially chose the key on which they had responded during the preceding (reversal of key assignment) experiment. However, within a few sessions both groups showed almost exclusive preference for the floor key. Preference for a key located on the floor may follow from the fact that pigeons are ground feeders and may thus be more "prepared" to peck the floor than to peck a wall. However, autoshaping, under the conditions prevailing here, occurred much more readily to the wall key, suggesting that pecking a vertical surface is more highly prepared. Difficulties in determining relative preparedness seem moot, however, given the lack of between-group differences in the intervening experiments. It is thus unlikely that schedule performances critically depend upon the specific operant response involved.