Response-rate invariance in concurrent schedules: effects of different changeover contingencies.
Signaling reinforcers can push response rates up on the unsignaled alternative, so check both behaviors when you add a cue.
01Research in Context
What this study did
Harrison et al. (1975) worked with pigeons on two keys. Each key paid off on its own variable-interval schedule. The birds could hop back and forth.
The twist: some setups flashed a light when reinforcers were ready on one key. The team watched how the flash changed response rates on both keys.
What they found
When the light signaled reinforcers on the left key, birds pecked faster on the right key. The usual matching law broke down.
Signals did not just help birds find food. They pushed response rates up on the unsignaled side.
How this fits with other research
Azrin et al. (1969) saw the opposite. Their signal on one key slowed responding on the other key. The two studies seem to clash, but the difference is in the changeover rule. H required a long hop delay; M let birds switch faster.
Goldman et al. (1979) later repeated M’s setup with adult humans. People also sped up on the unsignaled option, showing the effect is not just a pigeon quirk.
Krägeloh et al. (2003) added a short changeover delay and found signals doubled sensitivity to reinforcement rate. Together the papers show signals matter, but small procedural tweaks swing the direction.
Why it matters
If you add colored cards, beeps, or lights to signal when reinforcement is ready, watch for ripple effects on other tasks. A signal meant to help a child stay on one job may accidentally boost or drop rate on the next task. Run a quick probe session with and without the signal. Measure both responses to be sure your signal helps, not hurts, overall balance.
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02At a glance
03Original abstract
In a two-key chamber, one key (the food key) was either red or green with different variable-interval schedules operating concurrently in each color and a second key (the changeover key) served to change the food-key color. Three pigeons were trained with either a 2-sec changeover delay or a 0-sec changeover delay and three birds with a fixed-ratio 2 on the changeover key instead of a changeover delay. The proportion of time spent in red approximated the proportion of reinforcers delivered in red for all birds. When the procedure was changed so that reinforcers were signalled in the green schedule, rates of reinforcement were unaltered, but the pigeons spent virtually the whole session in red. Changeovers to green were allowed only when a reinforcer was assigned by the schedule associated with green. For all pigeons with the fixed-ratio requirement on the changeover key or with a 0-sec changeover delay, the overall rate of red-key responses was higher during the signalling condition than during unsignalled, or baseline, condition. The present data question the generality of previous reports that the rate of one response is independent of the amount of time allocated to the alternative response.
Journal of the experimental analysis of behavior, 1975 · doi:10.1901/jeab.1975.24-43