Reporting contingencies of reinforcement in concurrent schedules.
Discrimination of which choice is better fades with time since the last switch, so check soon after a client commits to one option.
01Research in Context
What this study did
The team set up two levers for lab pigeons. Each lever paid off on its own variable-interval schedule.
They then added a third task. Birds had to peck a key that told them which lever was currently the better deal.
The question: does changing the payoff odds on the third task change how the birds split time between the two main levers?
What they found
Shifting the payoff odds on the third task did not move the birds’ overall choice split.
But shifting the real payoff odds on the two main levers did change how well the birds could answer the third task.
Accuracy on the third task dropped the longer it had been since the bird last switched levers.
How this fits with other research
White (1979) already showed that making birds work harder to switch levers cuts switching and can create odd preferences. Jones et al. (1998) add the time piece: after a switch, the memory of which lever is better fades quickly.
Hunter et al. (1985) found that when payoff odds change, it takes about five daily sessions for birds to settle into a new stable split. The 1998 paper zooms in to show the fade starts within seconds after each switch.
McLean et al. (2018) later flipped the ratios every single day and saw choice still track within a session but get worse across days. Their rapid-change setup extends the 1998 warning: timing matters at every scale.
Why it matters
If you run concurrent reinforcement with kids—like two work stations or two play areas—do not assume they “know” which side is richer forever. Check their choice soon after they pick a side, because the signal fades. Quick probes or brief switches can keep the contingency clear and responding strong.
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02At a glance
03Original abstract
Five pigeons were trained on concurrent variable‐interval schedules in which two intensities of yellow light served as discriminative stimuli in a switching‐key procedure. A conditional discrimination involving a simultaneous choice between red and green keys followed every reinforcer obtained from both alternatives. A response to the red side key was occasionally reinforced if the prior reinforcer had been obtained from the bright alternative, and a response to the green side key was occasionally reinforced if the prior reinforcer had been obtained from the dim alternative. Measures of the discriminability between the concurrent‐schedule alternatives were obtained by varying the reinforcer ratio for correct red and correct green responses across conditions in two parts. Part 1 arranged equal rates of reinforcement in the concurrent schedule, and Part 2 provided a 9:1 concurrent‐schedule reinforcer ratio. Part 3 arranged a 1:9 reinforcer ratio in the conditional discrimination, and the concurrent‐schedule reinforcer ratio was varied across conditions. Varying the conditional discrimination reinforcer ratio did not affect response allocation in the concurrent schedule, but varying the concurrent‐schedule reinforcer ratio did affect conditional discrimination performance. These effects were incompatible with a contingency‐discriminability model of concurrent‐schedule performance (Davison & Jenkins, 1985), which implies a constant discriminability parameter that is independent of the obtained reinforcer ratio. However, a more detailed analysis of conditional discrimination performance showed that the discriminability between the concurrent‐schedule alternatives decreased with time since changing over to an alternative. This effect, combined with aspects of the temporal distribution of reinforcers obtained in the concurrent schedules, qualitatively predicted the molar results and identified the conditions that operate whenever contingency discriminability remains constant.
Journal of the experimental analysis of behavior, 1998 · doi:10.1901/jeab.1998.69-161