1. any distortion of or withholding of fact with the purpose of misleading others. For example, a researcher who has not disclosed the true purpose of an experiment to a participant has engaged in deception.

2. in nonhuman animal behavior, the provision of false information that results in the individual obtaining increased resources at the expense of others. Some animals give false alarm calls that disperse competitors and thus gain more food (see dishonest signal). Another form of deception is exhibited when certain animals engage in aggressive displays that make them appear larger than they really are. —deceive vb. —deceptive adj.