Effects of hunger and VI value on VI pacing.
Hunger and rich schedules boost response rates, but each learner’s timing pattern is unique.
01Research in Context
What this study did
WEINELong (1963) put hungry rats on variable-interval (VI) schedules.
The team changed two things: how hungry the rats were and how rich the schedule was.
They watched how fast the rats pressed and when they pressed within each interval.
What they found
Hungrier rats pressed faster. Richer VI schedules also raised rates.
Yet each rat timed its presses differently.
Some showed neat 8–10 second pauses between presses. Others burst or shifted their peaks.
How this fits with other research
Szempruch et al. (1993) later saw pigeons do the same thing—adjust wait time to interval length.
The bird data extend the rat finding: timing is flexible across species.
Sutphin et al. (1998) added a cost twist. Rats kept total daily effort low by eating fewer, bigger meals when cheap patches were scarce.
Together the three papers say: animals balance hunger, rate, and cost, but each body does it its own way.
Why it matters
Your client may respond more often when sessions fall before meals and when reinforcement is frequent.
Still, watch the individual pattern. One learner may pause neatly; another may burst.
Use that idiosyncratic rhythm to set mastery criteria instead of forcing a single timing mold.
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02At a glance
03Original abstract
In two experiments, each involving four rats, responses preceded by an inter-response time between 8 and 10 sec in duration were intermittently reinforced. In Experiment I, final performance was compared under two hunger levels, while the frequency of reinforcement was held constant by a VI 5 schedule. In Experiment II, hunger was held constant and VI 3 was compared with VI 8. Both hunger and frequency of reinforcement increased the over-all rate of response, but the exact effects of these operations on temporal discrimination were different for different rats. Usually, a peak "response probability" (IRTs/Op ratio) was obtained 8 to 10 sec after the preceding response, indicating adaptation to the reinforcement contingency, but in some cases this peak was about 2 sec earlier. One rat exhibited unusually pronounced bursting which seemed to alternate with adaptive temporally spaced responding. Prolonged pauses, observable in the cumulative records, particularly following reinforcement, were attributed to the fact that inter-response times greater than 10 sec were not reinforced, so that as the interval of time since the preceding response became discriminably greater than 10 sec, the probability of a response became small.
Journal of the experimental analysis of behavior, 1963 · doi:10.1901/jeab.1963.6-163