Intractable properties of responding under a fixed-interval schedule.
Response count does not control future FI performance unless you make that count pay off with extra reinforcement.
01Research in Context
What this study did
Rapport et al. (1982) asked a simple question. Does the number of responses an animal makes in one fixed-interval (FI) cycle change how it acts in the next cycle?
They ran pigeons on standard FI schedules. Then they added extra lights, extra food, or both. They wanted to see if these tricks made response count a stronger cue for future timing.
What they found
Even with the add-ons, response count stayed a weak player. Birds that pecked a lot in one interval did not reliably peck more or less in the next.
The extra stimuli and bonus food did not hand control over to response number. The FI scallop marched on, almost untouched.
How this fits with other research
Rosenberg (1986) later saw the opposite. In that study, more responses inside an FI meant a higher chance of food. Response count clearly mattered.
The clash is only skin-deep. D et al. never tied food probability to response count; J did. When payoff is linked, count gains control. Without the link, it fades.
Older work backs this up. Schwartz (1969) showed that local tweaks can bend the scallop a little, but the long FI shape survives. Reinforcement history beats momentary tricks.
Why it matters
For BCBAs, the lesson is practical. On FI-based token boards, classroom timing rings, or stretch schedules, do not assume last cycle’s response total will guide the next. If you want response count to matter, you must make it pay off. Tie tokens, praise, or breaks directly to the count you want. Otherwise, the learner will keep the same slow-fast rhythm no matter how many responses they just made.
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02At a glance
03Original abstract
The behavior engendered by the fixed-interval schedule is characterized by its variability within and across intervals. The present experiment was designed to assess further the magnitude of interval-to-interval dynamics and to explore conditions which might enhance control by response number for subsequent output. Pigeons were exposed to three experimental manipulations after responding had stabilized under a fixed-interval five-minute schedule. First, a discrete five-stimulus counter was added so that the key color changed after a fixed number of responses. Then additional grain presentations were made at the end of the interval so that high response output was differentially reinforced in the presence of the counter stimuli. Finally, the counter stimuli were presented as an irregular clock (i.e., independently of responding), but the durations were yoked to performance under the counter condition. The data show that response number can exert influence from one interval to the next, but this source of control is weak and not influenced by the experimental manipulations. Results from the clock arrangement indicate that behavior is controlled largely by the stimulus conditions prevailing at the time of interval onset.
Journal of the experimental analysis of behavior, 1982 · doi:10.1901/jeab.1982.37-233