PROPERTIES OF BEHAVIOR UNDER RANDOM INTERVAL REINFORCEMENT SCHEDULES.
Longer random-interval schedules reliably slow response rate in pigeons and people.
01Research in Context
What this study did
FARMELong (1963) watched pigeons peck a key for grain.
The grain came on random-interval schedules.
The team changed how often grain could pop up and saw how fast the birds pecked.
What they found
When the wait-time for grain got longer, the birds pecked slower.
The response rate slid down in a smooth curve as the T/P value grew.
How this fits with other research
Iwata et al. (1990) later tested toddlers with the same random-interval rule.
The kids also pecked slower under RI than under a ratio schedule, so the pigeon curve extends to humans.
WERTHEIWENZEL et al. (1964) tried the same idea with random-ratio schedules and found no clear rate curve.
That looks like a clash, but the difference is schedule type: interval gives a tidy rate drop, ratio does not.
Why it matters
You now have a rule of thumb: longer interval equals lower response rate, across species.
When you set a reinforcement timer in a token board or DRO, expect behavior to calm as the interval stretches.
Use this curve to spot if your client’s rate is on track or if extra motivation is needed.
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02At a glance
03Original abstract
In a temporally defined system of reinforcement schedules, the fixed interval case is defined when reinforcement probability, P, is equal to unity for the first response in any cycle length, T; when P is less than 1.0, random interval schedules emerge wherein T/P specifies the expected interval between reinforcements. Key-pecking rates were found to be: (a) inversely related to T/P; (b) higher at T=1.0 second than at other T parameter values; (c) low and linear at several T and T/P values. The mean post-reinforcement pause, if initially small, increased, and if initially large, decreased, as T/P increased.
Journal of the experimental analysis of behavior, 1963 · doi:10.1901/jeab.1963.6-607