Ratio responding as a function of concurrent avoidance schedules, yoked shocks, and ratio value.
Fixed-ratio response rates peak at medium sizes and crash when the schedule itself becomes aversive.
01Research in Context
What this study did
Rats pressed a lever on fixed-ratio schedules while shocks could hit at any time. A second group got the same shocks no matter what they did. The team tested ratios from 5 to 80 presses.
They wanted to know how big a ratio is 'too big' when shocks are in the background.
What they found
Response rates rose until the ratio hit 20–30 presses, then fell. At FR 80 many rats almost stopped. Extra shocks came when the ratio got large and pauses grew longer.
The yoked group showed the same shock pattern, so the drop was not just pain—it was ratio strain.
How this fits with other research
Gettinger (1993) later used yoked VR-VI schedules and proved the downturn is driven by long pauses, not slow pressing. The 1983 data look similar, but M gives you the cleaner fix: split pause time from run time.
MIGLELong (1963) first saw pigeons pecking a key to 'escape' big ratios. Bowe et al. (1983) add the shock layer and show the dip still happens when shocks are unavoidable.
Lea (1976) mashed an adjusting FR onto an FI and also saw high-ratio collapse. All three labs point to the same ceiling: once the ratio feels aversive, behavior breaks.
Why it matters
When you build a token board or response chain, keep each leg below the strain point. Watch for long pauses after payoff—those are early signs the ratio is turning punishing. If your learner stalls, cut the requirement or insert a brief break before you add more reinforcement.
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02At a glance
03Original abstract
Fixed-ratio food-reinforced responding in rats was studied alone and with concurrent shock avoidance or with concurrent response-independent shocks matched to those that occurred in the avoidance condition. Under each condition, fixed-ratio size was increased over successive daily sessions. Fixed-ratio response rate generally passed through a maximum as a function of fixed-ratio size. Decreased fixed-ratio responding at values beyond the maximum occurred when (1) the time to complete a fixed ratio approximated the response-shock interval of the avoidance schedule, (2) the shock rate increased, and/or (3) the ratio requirements were so high that ratio strain occurred. Avoidance rates decreased slightly as fixed-ratio size increased.
Journal of the experimental analysis of behavior, 1983 · doi:10.1901/jeab.1983.39-449