Effects of component length and of the transitions among components in multiple schedules.
Shorter schedule chunks alone can speed up responding, even when reinforcement stays the same.
01Research in Context
What this study did
The team worked with pigeons in a small lab.
Birds pecked a key under two different VI schedules that swapped every few minutes.
The researchers kept everything the same except the length of each schedule chunk.
They ran short chunks, then long chunks, and counted key pecks.
What they found
When chunks were short, the birds pecked faster.
When chunks were long, the birds pecked slower.
The change happened in both VI schedules, so it was not simple contrast.
The effect showed up every time they shortened the chunks.
How this fits with other research
Rogers-Warren et al. (1976) and Thomas et al. (1974) showed that taking away reinforcement in one chunk makes responding jump in the next chunk.
That jump is called behavioral contrast.
Bradshaw et al. (1978) says, "Our speed-up is not that jump."
They proved it by keeping reinforcement rates steady and only changing chunk length.
McSweeney et al. (1993) later mapped the full curve: contrast is biggest when the poor chunk lasts 30–60 s.
de Rose (1986) showed the same length rule works when the poor chunk is extinction and the rich one is fixed-interval.
Together, the papers say two separate knobs exist: one knob is chunk length, the other is reinforcement change.
You can turn either knob to raise response rate.
Why it matters
In therapy, you often flip between tasks or reinforcers.
If a child slows down, try cutting the time spent on each task before you switch.
Keep reinforcement the same—just make the chunk shorter.
This quick tweak can boost engagement without extra tokens or candy.
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02At a glance
03Original abstract
Pigeons received equal variable-interval reinforcement during presentations of two line-orientation stimuli while five other orientations appeared in extinction. Component duration was 30 seconds for all orientations and the sequence was arranged so that each orientation preceded itself and each other orientation equally often. The duration of one component (0 degrees ) was shortened to 10 seconds and the other (90 degrees ) was lengthened to 50 seconds. All animals showed large increases in response rate in the shortened component and this increase was recoverable after an interpolated condition in which all components were again 30 seconds in duration. This effect was replicated in a second experiment in which component duration was changed from 150 seconds to 50 seconds and 250 seconds. An examination of local contrast effects during the first experiment showed that the shortened component produced local contrast during subsequent presentations of the lengthened component, just as would a component associated with more frequent reinforcement. When the presentation sequence was changed so that the lengthened component was always followed by the shortened component, response rates generally increased during the lengthened component. When the sequence was arranged so that the shortened component always preceded the longer component, response rate decreased in the former. These effects, as well as the increases in response rate following change in component length, seem not to be the product of local contrast effects among components.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.29-3