Centrifugal selection of signal-directed pecking.

Pigeons were exposed to a schedule of stimulus-correlated food presentations. When key pecks terminated trial signals and cancelled the delivery of food, pecking was either gradually or rapidly redirected away from the keys, depending on whether the food-omission contingency was introduced from the outset or after exposure to a response-independent baseline. In all cases, the food-omission contingency substantially reduced or eliminated pecking at the keys.