title: Stimulus change contemporaneous with food presentation maintains responding in the presence of free food.
abstract: The presence or absence of a change in the ambient stimulus conditions upon entry into a food source controlled the frequency with which pigeons choose one of two concurrently available grain sources. Such changes characteristically accompany the production of response-produced food and account for prior reports of responding to produce food in the presence of freely available food.
authors.forename: R F
authors.initials: RF
authors.lastname: Wallace
authors.forename: S
authors.initials: S
authors.lastname: Osborne
authors.forename: J
authors.initials: J
authors.lastname: Norborg
authors.forename: E
authors.initials: E
authors.lastname: Fantino