Discrimination training facilitates pigeons' performance on one-trial-per-day delayed matching of key location.
Adding one non-reinforced choice during teaching doubled pigeons' memory span to 24 hours.
01Research in Context
What this study did
Northup et al. (1991) worked with pigeons on a one-trial-per-day memory game. The birds had to peck the same key location after a delay.
Half the birds got extra training. A second key lit up during the sample, but pecks there never paid off. This was the distractor.
What they found
Birds with the distractor key scored twice as high on the memory test. They stayed above chance even after a full day.
Without the distractor, accuracy dropped fast after a few hours.
How this fits with other research
Haemmerlie (1983) tested distractors placed during the delay and saw mixed results. J et al. moved the distractor to sample training and got a clear win.
Skrtic et al. (1982) mapped basic rules: short delays and long samples help. J et al. show a simple add-on—one non-reinforced key—can stretch memory to 24 h.
Dougherty et al. (1994) later boosted accuracy with different reinforcer sizes. J et al. did it without extra food, just by making the sample phase harder.
Why it matters
Discrimination training is a quick way to sharpen memory. When you teach a new skill, add a foil item that never pays off. The learner has to tell the real target apart from the foil, and the extra work firms up memory. Try it next time you run matching trials—insert one non-reinforced picture or location and watch recall last longer.
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02At a glance
03Original abstract
Six pigeons were tested on a one-trial-per-day variant of delayed matching of key location. In one condition, a trial began with the illumination of a pair of quasi-randomly selected pecking keys in a large 10-key test box. Pigeons' pecks to one key (the sample) were reinforced with 8-second access to grain on a variable-interval 30-second schedule, whereas pecks to the other key (the distractor) had no scheduled consequences. In the second condition, the nonreinforced distractor was not presented. In both conditions, subjects were removed from the apparatus after 15 minutes and placed in a holding cage. Subjects were subsequently replaced in the box after a delay (retention interval) of 30 seconds and were reexposed to the illuminated sample and distractor keys for 1 minute. If a pigeon made more pecks to the sample during this interval, the distractor was extinguished and subsequent pecks to the sample were reinforced on the previous schedule for an additional 15 minutes. If, however, a pigeon made more pecks to the distractor, both keys were extinguished and the subject was returned to its home cage. For all subjects, matching-to-sample accuracy was higher in the first condition. In a second experiment, the retention interval was increased to 5, 15, and 30 minutes, and then to 1, 2, 4, 8, 12, and 24 hours. Most subjects remembered the correct key location for up to 4 hours, and in one case, up to 24 hours, demonstrating a spatial-memory proficiency far better than previously reported in this species on delayed matching tasks. The results are discussed in terms of the commonly held distinction between working and reference memory.
Journal of the experimental analysis of behavior, 1991 · doi:10.1901/jeab.1991.55-201