from
http://www.wordiq.com/definition/Operant_conditioning
Accident allowed Skinner to uncover one
of his most important contributions, the
intermittent reinforcement schedule.
Initially, the free operant procedure
involved the delivery of one food pellet
per press of the lever. However, the food
dispenser often broke down, allowing lever
presses to occur unfollowed by food. Skinner
found that the animals would continue
working for some time before stopping.
This technique was exploited both to save
food pellets (which Skinner then made
himself), and later to uncover now well-known
properties of behavior under different
schedules of reinforcement. These are
commonly classified as interval or ratio
and fixed or variable schedules - with
interval schedules only giving out reinforcers
upon the first response after some period
of time, ratio schedules only giving out
reinforcers every so many responses, fixed
schedules having the same interval or ratio
throughout, and variable schedules enforcing
different intervals or numbers of responses
before each pair of reinforcers. Skinner's
initiation of this area of research, and
his surprisingly varied findings on the
effects of these different schedules on
the rate of a response, has led to broad
advances in our understanding of behavior
like gambling, drug use, piecework, or
waiting for the bus. Likewise, knowledge
of reinforcement schedules is essential
for animal training and forms a crucial
part of behavior therapies.