ABSTRACT
In the world outside the laboratory, 100% reward and 100% punishment must be very rare, if they exist at all. In buying radios or fruit, planning careers or weekends in the country, practicing tennis strokes or studying textbooks, hardly anything succeeds or fails every time. Even perfectly correct responses only earn rewards some of the time, often after long periods of persistence with little or no reward. Experiments on the effects of consequences that are only occasionally rewarding or punishing are more ecologically valid and relevant to life outside the laboratory than any other kind of research on learning.
