Concurrent performance as bouts of behavior.
A short changeover delay turns pigeon key pecking into measurable bouts whose sizes shift with reinforcement rate.
01Research in Context
What this study did
Pigeons pecked two keys for food. The keys ran on concurrent VI schedules. A changeover delay (COD) blocked reinforcement for a few seconds after each switch.
The team recorded every peck. They asked: does the COD create clear bouts of responding?
What they found
With the COD in place, pecks clustered into bouts. Longer bouts appeared on the key that paid off more often.
Bout length, pause length, and rate inside bouts all shifted with the reinforcement ratio.
How this fits with other research
Neuringer et al. (1968) already showed that a COD cuts down switching. Smith et al. (2014) go further: the same delay is what lets you see the bout structure at all.
Blue et al. (1971) warned to raise the COD slowly so obtained rates stay close to scheduled rates. The new data say those gradual steps also keep the bout pattern clean.
Fifty years of matching studies (S 1963; L et al. 1977) looked at molar proportions. This paper opens the microscope and shows the molecular bouts that produce those proportions.
Why it matters
If you run concurrent schedules in the lab or in a token economy, add a brief COD. It stops rapid switching and reveals whether your client works in steady bouts. Watch bout length: it tells you which alternative is really winning the reinforcement race.
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02At a glance
03Original abstract
Log-survivor analyses of interresponse times suggest that the behavior of rats responding under single variable-interval schedules is organized into bouts (i.e., periods of engagement and disengagement). Attempts to generalize this analysis to the key pecking in pigeons, however, have failed to produce the characteristic broken-stick appearance typically obtained with rats. This failure may be due to a relatively low rate of reinforcement for engaging in alternative behavior experienced by pigeons. The present study tested this hypothesis by exposing four pigeons to concurrent schedules of reinforcement for key pecking, first without a changeover delay (COD) and then with a COD. In this arrangement, one of the concurrent options was treated as the target response and the rate of reinforcement for that option was manipulated across conditions. The other option provided explicit reinforcement for engaging in an alternative response (i.e., explicit reinforcement for disengaging from the target response). In the absence of a COD, log-survivor plots for three of the pigeons were approximately linear, thus providing no evidence that responding was organized into bouts. When a COD was present, plots were broken stick in appearance, indicating a bout structure had been generated in the pigeons' behavior. Both bout length and the rate of bout initiations were a function of differences in rate of reinforcement. These data suggest that behavior may become organized into bouts when contingencies create sufficiently long visits to both the target behavior and the extraneous behavior. Fits of a double-exponential model deviated systematically from the actual plots due to the presence of a plateau between the two limbs. An alternative, double-gamma, model was explored, and it provided a considerably better fit than did the double-exponential.
Journal of the experimental analysis of behavior, 2014 · doi:10.1002/jeab.90