An aspect of learning by which animals rapidly learn to avoid poisoned food. Rodents are notorious for their bait shyness. Rats (Rattus norvegicus) that eat a small amount of poisoned food and survive will never touch that type of food, again. When a rat comes across a novel food, it initially eats only a very small amount. The intervals between meals are sufficiently long to enable the rat to assess the consequences of eating a new food. When a rat eats, some of the food passes rapidly through the stomach into the small intestine, bypassing the previous meal that is still in the stomach. In this way the rat can test small quantities of the food that it has eaten most recently. Rats show considerable stimulus relevance, readily associating the novel taste or smell of food with internal physiological consequences, and not associating them with other consequences. Even if the consequences of eating are delayed by 24 h, the rat associates deleterious consequences, such as sickness, with the food it has eaten, and not with other behaviour that has occurred during the interval. A single experience of a poisoned food is sufficient to establish avoidance of that type of food. Similar phenomena occur in birds, although they usually form avoidance associations with the visual properties of the food. The mechanisms of poison avoidance have a close affinity with those of food selection in general.
Subjects: Zoology and Animal Sciences.