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Click on the thumbnail below to enlarge	Schedules of Reinforcement
	Schedules of reinforcement are the rules that determine how often an organism is reinforced for a particular behavior. The particular pattern of reinforcement has an impact on the pattern of responding by the animal. A schedule of reinforcement is either continuous or partial. The behavior of the Fire Chief Rabbit to the left was not reinforced every time it pulled the lever that "operated" the fire truck. In other words, the rabbit's lever pulling was reinforced on a partial or intermittent schedule. There are four basic partial schedules of reinforcement. These different schedules are based on reinforcing the behavior as a function of (a) the number of responses that have occurred or (b) the length of time since the last reinforcer was available. The basic four partial schedules are: Fixed Ratio, Variable Ratio, Fixed Interval, and Variable Interval
Click on the thumbnail below to enlarge	Continuous Schedule
	The continuous schedule of reinforcement involves the delivery of a reinforcer every single time that a desired behavior is emitted. Behaviors are learned quickly with a continuous schedule of reinforcement and the schedule is simple to use. As a rule of thumb, it usually helps to reinforce the animal every time it does the behavior when it is learning the behavior. Later, when the behavior is well established, the trainer can switch to a partial or intermittent schedule. If Keller Breland (left) reinforces the behavior (touching the ring with nose) every time the behavior occurs, then Keller is using a continuous schedule.
Click on the thumbnail below to enlarge	Partial (Intermittent) Schedule
	With a partial (intermittent) schedule, only some of the instances of behavior are reinforced, not every instance. Behaviors are shaped and learned more slowly with a partial schedule of reinforcement (compared to a continuous schedule). However, behavior reinforced under a partial schedule is more resistant to extinction. Partial schedules of reinforcement are based on either a time interval passing before the next available reinforcer or it is based on how many behaviors have occurred before the next instance of the behavior is reinforced. Schedules based on how many responses have occurred are referred to as ratio schedules and can be either fixed-ratio or variable-ratio schedules. Schedules based on elapsed time are referred to as interval schedules and can be either fixed-interval or variable-interval schedules.
Click on the thumbnail below to enlarge	Fixed Ratio Schedule
	Ratio schedules involve reinforcement after a certain number of responses have been emitted. The fixed ratio schedule involves using a constant number of responses. For example, if the rabbit is reinforced every time it pulls the lever exactly five times, it would be reinforced on an FR 5 schedule.
Click on the thumbnail below to enlarge	Variable Ratio Schedule
	Ratio schedules involve reinforcement after an average number of responses have occurred. For example, the Fire Chief Rabbit's lever pulling, which made it appear that it was operating the fire truck, was reinforced on a variable-ratio schedule.  Reinforcement occurred after an average of 3 pulls on the lever. Sometimes the reinforcer was delivered after 2 pulls, sometimes after 4 pulls, sometimes after 3 pulls, etc. If the average was about every 3 pulls, this would be a VR 3 schedule. Variable ratio schedules maintain high and steady rates of the desired behavior, and the behavior is very resistant to extinction.
	Fixed Interval Schedule
	Interval schedules involve reinforcing a behavior after an interval of time has passed. In a fixed interval schedule, the interval of time is always the same. In an FI 3-second schedule, the first response after three seconds have passed will be reinforced, but no response made before the three seconds have passed will be reinforced. ABE did not use this type of schedule very often.
	Variable Interval Schedule
	Interval schedules involve reinforcing a behavior after an variable interval of time has passed. In a variable interval schedule, the interval of time is not always the same but centers around some average length of time.  In a VI 3-second schedule, the first response after three seconds (on average) have passed will be reinforced, but no responses made before the three seconds (on average) have passed will be reinforced. After an animal learns the schedule, the rate of behavior tends to be steadier than with a fixed interval schedule. ABE did not use this type of schedule very often.