Concurrent second-order schedules of reinforcement.
Matching fails under layered second-order schedules—short early intervals hog most responses.
01Research in Context
What this study did
Cohen (1975) worked with pigeons on two keys. Each key ran a second-order schedule.
A brief fixed-interval came first, then a longer variable-interval. Food arrived only after the VI ended.
The birds could hop keys at any time. The setup tested if matching still holds when schedules stack inside each other.
What they found
The birds did not match the printed rates. They leaned hard on the key with the shorter fixed part.
In plain words, the short wait inside the schedule pulled more pecks than the math said it should.
How this fits with other research
Chandler et al. (1992) later showed kids in class do follow matching when teachers give praise on VI clocks. The classroom data line up with simple VI, not with L’s nested second-order mess.
Schlundt et al. (1999) gave college students colored lights that told them which schedule was active. With those cues, the students matched almost perfectly. The pigeons in L had no such lights, which may explain why their choice drifted.
O'leary et al. (1969) had already shown that brief food-paired stimuli keep second-order patterns alive. L added the twist of two schedules side-by-side and found the short FI piece steals extra responses.
Why it matters
If you run token boards or chained schedules, watch the early short links. Clients may over-work them even when the later pay is thin. Add clear stimuli or stretch the early interval to keep choice balanced.
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02At a glance
03Original abstract
Responses on one key (the main key) of a two-key chamber produced food according to a second-order variable-interval schedule with fixed-interval schedule components. A response on a second key (the changeover key) alternated colors on the main key and provided a second independent second-order variable-interval schedule with fixed-interval components. The fixed-interval component on one variable-interval schedule was held constant at 8 sec, while the fixed interval on the other variable-interval schedule was varied from 0 to 32 sec. Under some conditions, a brief stimulus terminated each fixed interval and generated fixed-interval patterns; in other conditions, the brief stimulus was omitted. Relative response rate and relative time deviated substantially from scheduled relative reinforcement rate and, to a lesser extent, from obtained relative reinforcement rate under both brief-stimulus and no-stimulus conditions. Matching was observed with equal components on both schedules; with unequal components, increasingly greater proportions of time and responses than the matching relation would predict were spent on the variable-interval schedule containing the shorter component. Preference for the shorter fixed interval was typically more extreme under brief-stimulus than under no-stimulus schedules. The results limit the extension of the matching relation typically observed under simple concurrent variable-interval schedules to concurrent second-order variable-interval schedules.
Journal of the experimental analysis of behavior, 1975 · doi:10.1901/jeab.1975.24-333