Presence of conspecifics facilitates learning that food is inedible in Aplysia fasciata.

The absence of a conspecific, but not of food, interfered with learning and memory of a feeding task in Aplysia fasciata. Interference was shown by a shortened training session and by lack of savings on retraining. The shortened training is not responsible for the lack of savings because brief training in the presence of a conspecific led to savings on retraining. Animals trained in the absence of a conspecific and then tested in its presence did not show signs of having learned, which indicates that the absence of a conspecific interfered with the ability to learn, rather than with the expression of memory. Absence of a conspecific also inhibited other aspects of feeding behavior, such as the latency to respond to food and the length of time that animals respond to food, which indicate that interference with learning was apparently caused by inhibition of feeding behavior, rather than by block of the mechanisms underlying learning.