Development of food recognition in young chicks: IV. Associative and nonassociative effects of experience.

Abstract

Three-day-old chicks were allowed to peck food, sand, or mealworms [Tenebrio larvae] or were force-fed liquid food, glucose water, or water and were tested later on either food or sand. Only experience that involved pecking led to the development of a discrimination between food and sand based on short-term metabolic feedback. These and previous results can be accounted for by postulating that the act of pecking and a hunger coordinating mechanism develop independently but experience is necessary for the association of pecking with the hunger system (i.e., chicks must learn that pecking leads to ingestion). After this association is formed, unlearned physiological mechansims could modulate the rate of pecking directly. Immediate discrimination between food and sand, based on taste cues, occurred when chicks had 3 separate experiences in ingesting food. This result can be accounted for by using a standard discrimination learning paradigm.