CHAINED VI PERFORMANCE OF PIGEONS MAINTAINED WITH AN ADDED STIMULUS.
Big, obvious steps toward the reinforcer speed responding more than the schedule that earns them.
01Research in Context
What this study did
Four pigeons pecked a key in a two-link chain.
The first link paid on a variable-interval (VI) schedule.
The second link always ended with food, but first a voltmeter needle moved one step.
The steps were big (10) or small (2).
The VI could be 30 s or 120 s.
Researchers counted how fast the birds pecked during the first link.
What they found
Pecks sped up as the final food got closer.
Big steps (10) made the birds rush more than small steps (2).
Changing the VI length mattered less than changing the step size.
The birds worked hardest when each peck visibly moved the meter a lot.
How this fits with other research
Sheldon (1971) later used fixed-ratio links instead of VI.
He saw short pauses at the start when most work sat at the end.
Together the papers show: what counts is how soon and how clearly the next event arrives, not just the schedule type.
Steege et al. (1989) added humans to the same chained setup.
People chased the best overall money rate, while pigeons still followed the meter steps.
The bird data line up; the species differ only in what they value.
Why it matters
Your client’s token board is a chained schedule.
Make each token a big, visible step toward the prize.
A clear jump every time beats a perfect schedule you can’t see.
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02At a glance
03Original abstract
Pecks at a first (left) key were reinforced by a partial movement (advance) of the voltmeter behind the key toward the maximum position. When the meter reached maximum deflection, pecks at a second key were continuously reinforced with food. The schedule of reinforcement by which pecking the first key produced a deflection, as well as the size of the deflection, were varied in a series of experiments. The rate of responding on the first key was more affected by changes in the number of steps required to move the meter to the maximum position (the size of the deflection) than by the value of the variable-interval schedule by which pecking produced a meter deflection. The rate at which the bird pecked was low when the meter was near the null position, and high as the meter approached the maximum deflection.
Journal of the experimental analysis of behavior, 1964 · doi:10.1901/jeab.1964.7-83