Choice between sequences of fixed-ratio schedules: effects of ratio values and probability of food delivery.
The first response requirement in a chain wields the biggest say in what your learner picks.
01Research in Context
What this study did
Pigeons pecked two keys. Each key started a chain of fixed-ratio schedules.
The first ratio was small on one side and large on the other. Sometimes the small-ratio side also gave less food.
Birds chose again and again. Researchers watched which chain they picked.
What they found
The birds almost always picked the chain that began with the smaller ratio.
They did this even when that side paid food less often.
When the first ratios were equal, the birds then looked at the second ratio size.
How this fits with other research
McClannahan et al. (1990) saw the same pattern. Their birds also fled from big early ratios, but they added forceful pecks and delayed food. The dislike of early work stayed the same.
Meuret et al. (2001) later cycled ratio sizes within one session. They found the descending part of the cycle held the most power, just like the 1987 study shows the first link holds the most power.
Bailey et al. (1990) shifted food probability on the fly. Birds chased the richer side faster when the difference was large. This extends the 1987 result: once the first ratio is equal, probability grabs control.
Why it matters
Your clients also hate long first steps. Break early tasks into tiny ratios, then slowly stretch the later ones. If two paths start equal, only then will payoff size steer the choice.
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02At a glance
03Original abstract
Pigeons were exposed to schedules of food delivery that consisted of two sequential fixed ratios. When alternative sequences provided two food deliveries per 50 responses, the schedule with the shorter initial fixed-ratio value was consistently preferred. Progressively reducing from 1.0 to .25 the probability of food delivery following completion of the second fixed ratio of the sequence with the shorter initial fixed ratio did not reduce preference for this sequence. Moreover, the sequence with the shorter initial fixed ratio also was preferred when the probability of food delivery following completion of the initial ratio in that sequence was progressively reduced from 1.0 to .5, although preference shifted to the alternative when the probability was reduced to 0. These findings suggest that the length of the initial fixed ratio was a primary determinant of choice. Subsequent manipulations demonstrated, however, that when the initial fixed ratios of the two alternatives were equal, changes in the ratio value and probability of food delivery following completion of the second fixed ratio lawfully affected choice.
Journal of the experimental analysis of behavior, 1987 · doi:10.1901/jeab.1987.47-225