Development of key-pecking, pause, and ambulation during extended exposure to a fixed-interval schedule of reinforcement.
Pause duration on an FI schedule is the tortoise—plan for many baseline sessions until it settles.
01Research in Context
What this study did
Researchers watched pigeons peck a key for 200 sessions. The birds earned food on a fixed-interval 3-min schedule.
The team tracked three things: key-pecks, pause after food, and walking around. They wanted to see when each measure would settle into a steady pattern.
What they found
Key-peck rate settled first. Pause length took much longer to stabilize.
Walking slowly dropped but stayed highest during the pause. The classic FI “scallop” showed up, yet pause control was the last piece to lock in.
How this fits with other research
Nevin (1969) first drew the two-state picture: long pause, then sudden rush of pecks. Falcomata et al. (2012) extend that work by showing the pause is the slower partner to stabilize.
Kodera et al. (1976) tried to stretch the pause by dropping extra food during it; the pause barely budged. Their finding pairs with the new data: once the pause finally firms up, it is hard to nudge, so give it time before you test any manipulation.
Winett et al. (1972) broke the FI into short trials and got cleaner curves faster. That contrast highlights why free-operant studies need the long runway that S et al. used.
Why it matters
If you run FI or FI-based assessments, do not quit at 20 sessions. Pause duration keeps cooking long after response rate looks fine. Let the bird (or client) season for 40, 60, maybe more exposures before you call it stable and move on.
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02At a glance
03Original abstract
Six pigeons key-pecked under a fixed-interval (FI) 3-min schedule of food presentation. Each pigeon was studied for 200 daily sessions with 15 intervals per session (3,000 total food presentations). Analyses included the examination of latency to first peck (pause), mean rate of key pecking, and ambulation. Characterizations of stable performance were assessed across measures of behavior and evaluated using commonly employed stability criteria. Stability of response rate and pause was identified better by assessments that evaluated variability and trend, rather than just variability. Between-subject differences in rate of acquisition and terminal values of steady-state performance of pause were observed, and stable pause durations took longer to develop than did stable key-pecking rates. Relative variability in response rate and pause duration decreased as the means increased. A temporally organized pattern of key-pecking (the so-called FI scallop) developed within 50 sessions of exposure to the schedule. Overall ambulation decreased during the early sessions of exposure and further analyses showed greater rates of ambulation during the pause than after it for 4 of the 6 pigeons. Performance under the FI 3-min schedule developed relatively slowly, and key-pecking, pause, and ambulation developed at different rates.
Journal of the experimental analysis of behavior, 2012 · doi:10.1901/jeab.2012.97-333