Fixed-interval matching-to-sample: intermatching time and intermatching error runs.
Reinforcement timing within fixed intervals affects matching accuracy mainly just before reinforcement, not across the whole interval.
01Research in Context
What this study did
The team ran a matching-to-sample task on fixed-interval (FI) schedules. They watched how long each gap between correct matches lasted and how many wrong answers happened in a row.
The goal was to see if timing inside the interval shaped accuracy from start to finish.
What they found
Accuracy and speed rose only near the moment of reinforcement. The rest of the interval showed weak control; errors could string together for long stretches.
Adding a tandem FR requirement at the end helped a little, but the middle of the interval stayed sloppy.
How this fits with other research
Catania et al. (1972) first showed the same mid-interval dip the target paper saw. Their data and the new data line up; both find the low point halfway to reinforcement.
Austin et al. (2015) swapped in response-initiated FI schedules and saw even looser timing. Together the three studies warn: if the learner starts the clock, stimulus control weakens further.
Schwarz et al. (1970) counted pigeons’ pecks and found response timing settled only after the sixth response. The target paper adds that, even after responses stabilize, accuracy can still drift until the payoff is close.
Why it matters
When you use FI schedules for fluency or maintenance, drop extra cues or brief differential reinforcement in the middle two-thirds of the interval. Without them, the learner may practice errors while waiting for the clock to wind down.
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02At a glance
03Original abstract
Four pigeons were trained on a matching-to-sample task in which reinforcers followed either the first matching response (fixed interval) or the fifth matching response (tandem fixed-interval fixed-ratio) that occurred 80 seconds or longer after the last reinforcement. Relative frequency distributions of the matching-to-sample responses that concluded intermatching times and runs of mismatches (intermatching error runs) were computed for the final matching responses directly followed by grain access and also for the three matching responses immediately preceding the final match. Comparison of these two distributions showed that the fixed-interval schedule arranged for the preferential reinforcement of matches concluding relatively extended intermatching times and runs of mismatches. Differences in matching accuracy and rate during the fixed interval, compared to the tandem fixed-interval fixed-ratio, suggested that reinforcers following matches concluding various intermatching times and runs of mismatches influenced the rate and accuracy of the last few matches before grain access, but did not control rate and accuracy throughout the entire fixed-interval period.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.29-105