Stimulus change contemporaneous with food presentation maintains responding in the presence of free food.
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.
Wallace
R F
RF
Osborne
S
S
Norborg
J
J
Fantino
E
E