Food delivery as a conditional stimulus: Feature-learning and memory in pigeons.
A tiny food cue right before reinforced trials makes pigeons learn faster than when the cue signals no reward.
01Research in Context
What this study did
Researchers worked with pigeons in a small lab chamber. Before each trial the bird got a tiny food snack or nothing.
The snack acted like a green light. It told the bird this trial would pay off with more food. Other times the snack meant no food would come.
The team watched how fast each bird learned to tell the difference between these two set-ups.
What they found
Birds learned the task faster when the pre-trial snack signaled food was coming. This is called feature-positive.
When the snack signaled no food, learning slowed down. This is feature-negative.
The same bird showed both patterns, so the effect is strong and repeatable.
How this fits with other research
Jenkins et al. (1973) showed pigeons like to look at stimuli that predict food. Bottjer et al. (1979) now shows these cues also speed up learning.
Pomerleau et al. (1973) found brief food-paired stimuli can keep pigeons pecking. The new study adds that the cue must come before the trial, not after, to help learning.
Downing et al. (1976) mixed food and non-food events randomly. W et al. kept the cue steady, proving the cue's meaning, not randomness, drives the speed-up.
Why it matters
You can use this when teaching new skills. Give a small reward right before the trial that will pay off. Skip the reward before trials you want the learner to ignore. This simple switch can cut training time in half.
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02At a glance
03Original abstract
Three experiments investigated the learning and memory of discriminations based on presence versus absence of a pre-trial food delivery. In Experiment 1 half the illuminations of a response key were followed by food regardless of the subject's behavior. In one group an extra food delivery preceded only reinforced trials (feature-positive condition), whereas in a second group it preceded only nonreinforced trials (feature-negative condition). Key pecks and approaches revealed more rapid and superior discrimination learning in the first group. Experiment 2 replicated the results of Experiment 1 but yielded no evidence that greater "unexpectedness" of pretrial food conditions facilitates discriminative performance. In Experiment 3, individual pigeons trained on a conditional discrimination exhibited a within-subject feature-positive superiority. Delay between pretrial and trial stimuli interacted with feature-positive versus feature-negative training in both the between-group (Experiment 2) and within-subject (Experiment 3) procedures: performance was decremented at both short and long delays in the feature-positive condition but was decremented only at longer delays in the feature-negative condition. The feature-positive superiority obtained here is incompatible with explanations based on either the general concept of "perceptual organization" or on the conditional nature of feature-negative discriminations.
Journal of the experimental analysis of behavior, 1979 · doi:10.1901/jeab.1979.31-189