Six pigeons responded on two keys in each of three signalled multiple-
schedule components, and resistance to disruption of responding on one
(target) key by extinction and by response-independent food presented
during inter-component blackouts was studied. Alternative reinforceme
nt of different magnitudes was contingent on pecking a non-target key
in two components, and in the third only the target response was reinf
orced. Resistance to change varied with the overall quantity of reinfo
rcement in the component, regardless of whether reinforcers were conti
ngent on the target or non-target response, but did not differ across
the two key locations. These results using different magnitudes of rei
nforcement confirm previous findings using rate of reinforcement as th
e variable, and suggest that resistance to change is dependent on stim
ulus-reinforcer rather than response-reinforcer contingencies.