Fractional punishment of fixed-ratio performance.
Shock timing inside a fixed-ratio chain decides whether the bird pauses longer or stumbles near the finish line.
01Research in Context
What this study did
Dardano (1970) shocked pigeons at different spots inside a long fixed-ratio chain. The birds had to peck 70 times to earn food. A mild shock came after peck 15, 35, 55, or 70.
The team watched how the pause and running rate changed when the shock moved. They wanted to know if timing inside the chain matters.
What they found
Shock early in the chain made the pigeon wait longer before it started pecking. Shock late in the chain broke the burst just before food. Very weak shock sometimes made the birds peck faster.
Same shock, different spot, different result. Location inside the ratio drove the size and shape of suppression.
How this fits with other research
Dodd et al. (1977) ran almost the same study and saw the same pattern: early shocks hurt more. This direct replication gives us confidence the early-late rule is real.
Dardano (1972) let pigeons pick where the shock would land. Birds usually chose the same spots that caused the least trouble in the first study. The choice data line up with the suppression data.
Lande (1981) moved the lens to variable-ratio schedules and found that shock can create short bursts of fast responding. This extends the 1970 finding by showing timing effects also appear when the ratio length changes every time.
Why it matters
When you use response interruption or aversive feedback, place it as early as possible in the response chain. Early consequences stop the whole sequence. Late consequences only scramble the final steps and can leave the front half untouched. If you must punish, hit the first response, not the last.
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02At a glance
03Original abstract
Key-peck responses of pigeons under a fixed-rate 60 (Exp. I) or fixed-ratio 99 (Exp. II) schedule of positive reinforcement were punished by response-dependent electric shock during a segment of the ratio. The punishing stimulus was scheduled in one of three locations: the first third of the ratio, the middle third, or the final third. At high shock levels, the different loci of punishment differentially affected the typical fixed-ratio performance pattern. Post-reinforcement pauses were lengthened by all punishment conditions but to a greater degree when the responses in initial third of the ratio were punished. Disruption of responses before the punished segment of the ratio was a conspicuous feature of the performances when the middle or final third of the ratio was punished. Two of the punishment conditions produced similar effects on both fixed-ratio baselines but punishing the final third of the ratio suppressed the punished responses of the ratio only with the fixed-ratio 99 schedule. General effects of all punishment conditions included consistent intra-session recoveries of partially suppressed performances, the rapid recovery of the FR performances after the punishment dependency was removed after complete suppression, and the facilitation of overall and/or local response rates of most subjects by low-intensity shock.
Journal of the experimental analysis of behavior, 1970 · doi:10.1901/jeab.1970.14-185