Conditioned reinforcement and choice with delayed and uncertain primary reinforcers

Area of Science:

• Behavioral Psychology
• Animal Cognition

Background:

• Pigeons were studied using an adjusting-delay choice procedure.
• The study investigated how conditioned reinforcers influence choice behavior.

Purpose of the Study:

• To determine how the presence or absence of food, signaled by houselights, affects pigeons' key pecking preferences.
• To test a hyperbolic decay model for conditioned reinforcer strength.

Main Methods:

• Pigeons chose between red and green keys, with red yielding a variable delay to food.
• Green key trials varied in food delivery (all, half, or none) and associated houselight durations (10s or 30s).
• Indifference points were calculated to quantify key preference.

Main Results:

• Preference for the green key decreased when food was absent on half the trials, regardless of houselight duration.
• Preference for the green key increased when food was absent on half the trials, but only when the houselight duration was shorter (10s).
• A hyperbolic decay model accurately predicted choice behavior across conditions.

Conclusions:

• Houselights function as conditioned reinforcers, influencing choice behavior.
• Conditioned reinforcer strength is inversely related to the time spent in its presence before primary reinforcement.
• The findings demonstrate a scenario where preference increases with partial omission of reinforcement.