n.1. the way in which materials are set before an individual, often for the purpose of learning or understanding. 2. the act of exposing a human or nonhuman animal to stimuli or learning materials during an experiment. 3. in psychoanalytic theory, the means or vehicle through which an instinct is expressed. 4. in interpersonal relations and social interaction, the way in which an individual behaves or expresses himself or herself. 5. in animal behavior, see presenting. —presentvb.