title: Concurrent avoidance of shocks by pigeons pecking a key.
abstract: Three pigeons were studied on concurrent, unsignaled, avoidance schedules in a two-key procedure. Shock-shock intervals were two seconds in both schedules. The response-shock interval on one key was always 22 seconds, while the response-shock interval associated with the other key was varied from 7 to 52 seconds in different experimental conditions. Response rates on the key associated with the varied schedule tended to decrease when the response-shock interval length was increased. Responding on the key associated with the constant schedule was not systematically affected.
authors.forename: E A
authors.initials: EA
authors.lastname: De Moraes Ferrari
authors.forename: J C
authors.initials: JC
authors.lastname: Todorov