Changeover delay and concurrent-schedule performance in domestic hens.
A 5–15 s changeover delay tightens matching in concurrent schedules by reducing impulsive switches.
01Research in Context
What this study did
The team worked with six domestic hens in a lab chamber. Two side keys delivered grain on separate VI schedules. A center key served as the changeover key.
They tested three changeover delays: 0 s, 5 s, and 15 s. Sessions ran until daily response ratios stabilized.
What they found
When the delay rose from 0 s to 15 s, the birds’ response ratios moved closer to the reinforcement ratios. The 15-s delay produced near-perfect matching.
Longer delays also cut rapid switching between keys. Sensitivity scores doubled, showing sharper discrimination of which key paid off more.
How this fits with other research
Murphy (1982) saw the opposite: longer delays lowered pigeons’ signal-key pecking. The tasks differ. G used a single signal key that sometimes paid off; the current study used two separate reinforcement keys. The delay broke accidental chains in G’s setup but sharpened true choice here.
McSweeney (1975) showed pigeons already match without a delay. Adding the delay in the hen study simply tightened the match, extending K’s baseline finding to a new species and procedure.
Corrigan et al. (1998) found that unsignaled delays hurt response rates. Here, the delay is signaled by the changeover key and occurs only after a switch, so rates stay strong while choice improves.
Why it matters
If a client rapidly flips between two tasks or reinforcers, a brief lock-out can calm the shuffle and make the richer option stand out. Try inserting a 5–10 s changeover delay when teaching choice between two VI activities, such as two play stations or work bins. Track response allocation across sessions; you should see the learner spend more time in the higher-pay area without losing overall engagement.
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02At a glance
03Original abstract
Six domestic hens were exposed to a series of five pairs of two-key concurrent variable-interval schedules with a range of changeover delays from no delay to 15 s. Times spent responding on each alternative and total, within_, and post-changeover-delay response ratios were analyzed in terms of the generalized matching law. The sensitivity parameters, a, for response and time data were generally low when no changeover delay was programmed but were not 0.0. They were higher for all other changeover-delay values, with some tendency to increase as the changeover delay lengthened at very short delays. Within-delay responding was insensitive to reinforcement-rate differences at all changeover delays (a values close to 0.0). As a result of this insensitivity, post-changeover-delay responding was more sensitive to reinforcement-rate changes than was total responding. Interchangeover intervals increased systematically with changeover-delay duration. Responding, particularly after the changeover delay, was well predicted by an equation based on a reinforcer-loss model.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.63-71