THE EFFECT OF MULTIPLE S-DELTA PERIODS ON RESPONDING ON A FIXED-INTERVAL SCHEDULE. II. IN A PRIMATE.
Brief S-delta periods suppress responding yet leave the FI scallop intact in primates.
01Research in Context
What this study did
The team worked with a primate on a fixed-interval schedule.
They slipped in several S-delta periods where no food could be earned.
The goal was to see if the animal still showed the smooth scallop pattern seen in earlier pigeon work.
What they found
During each S-delta the monkey almost stopped pressing.
Yet the overall curve kept its classic FI scallop once reinforcement returned.
The pigeon result held true for a primate brain.
How this fits with other research
Innis (1978) saw the same brief drop with pigeons when one VI link paid more than the other.
Bloomfield (1967) also found quick contrast swings under multiple FR schedules.
Together the three papers show that short no-pay signals briefly suppress behavior across species and schedule types.
Why it matters
If you insert brief extinction cues into a timing schedule, expect a short pause, not a lost pattern.
This lets you add error-correction or teaching trials without ruining the larger rhythm you worked to build.
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Join Free →Add a 10-second extinction cue mid-interval; watch for a quick dip, then resume reinforcement to keep the scallop.
02At a glance
03Original abstract
A squirrel monkey was subjected to a fixed-interval pattern of reinforcement. During the course of each interval a bright white light was repeatedly presented. In the presence of the white light, a response was never immediately followed by food; the white light thus functioned as S(Delta). Responding was interrupted during the S(Delta) periods, but in the squirrel monkey as in the pigeon, these interruptions did not destroy the characteristic scalloped pattern of the cumulatively recorded responding through each interval.
Journal of the experimental analysis of behavior, 1965 · doi:10.1901/jeab.1965.8-53