Chapter Six- Schedules of Reinforcement and Choice Behaviour
Causal Reflection suggests that such a perfect contingency between response and reinforcement is rare in the real world- you do not get a
high grade on a test every time you study for it.
A schedule of reinforcement= a program or rule that determines which occurrence of a response is followed by the reinforcer
-There are many ways that the program could be set up, the delivery of a reinforcer can depend on the occurrence of a certain number of
-The passage of time
-The presence of certain stimuli
-The occurrence of other responses etc.
Schedules of reinforcement influence both how an instrumental response is learned and how it is then maintained by reinforcement.
-The behavioural effects of drugs, brain lesions, or manipulations of neurotransmitter systems often depend on the schedule of
reinforcement that is in effect during the behavioural testing.
Simple Schedules of intermittent reinforcement
- Processes that organize and direct instrumental performance are activated in different ways by different schedules of reinforcement.
-In simple schedules, a single factor determines which occurrence of the instrumental response is reinforced.
-Reinforcement depends only on the number of responses the organism has performed. Just counting the number of responses that have
occurred, and delivering the reinforcer when the required number is reached.
-If the required number is one, it is called a continuous reinforcement (CRF)
-Situations in which responding is reinforced only some of the time are said to involve partial or intermittent reinforcement.
E.g. biting into a strawberry should bring a good flavour, but sometimes it is rotten
-When there’s a fixed ratio between the number of responses the rat made and the number of reinforcers it got (e.g. ten responses per
reinforcer, where it would be called a fixed-ratio 10 or FR 10)
-CRF is also on a fixed-ratio schedule: one response per reinforcement.
-A typical pattern of a fixed-ratio schedule is a steady to high rate of responding once the behaviour gets under way, but there
may be a pause before the start of the required number of responses. E.g. you may pause before typing a phone number in but once you
started you most likely will not pause. These features are evident in the cumulative record
-A Cumulative record is a special way of representing how a response is repeated over time, showing the total number of
responses that occurred up to a particular point in time. It creates a chart, looking like steps – line remains horizontal when no responding
is created but makes one vertical line every time a response is made.
-The slope of the line made by the cumulative record represents the subject’s rate of responding: the zero rate of responding that
occurs right after reinforcement is called the post-reinforcement pause. The high and steady rate of responding that completes each ratio
requirement is called the ratio run
-Ratio strain: the increase in ratio requirements = a longer post-reinforcement pause.
Variable-Ratio Schedule (VR)
-The numerical value of a variable-ratio schedule indicates the average number of responses required per reinforcer. E.g. If you need a
pigeon to make a 10 responses to earn the first reinforcer, 13 to e