1. sensory discrimination of differences among stimuli. For example, wines that at first taste are identical may, with experience, be readily distinguished.

2. a conditioning process in which a limited range of behavior types is achieved through selective reinforcement of only some forms of behavior. Also called response differentiation.

3. in embryology, the process whereby cells of a developing embryo undergo the changes necessary to become specialized in structure and function so that they or their successors can form tissues, such as muscle, neurons, or bone.

4. in mathematics, the process used in calculus for obtaining the differential coefficient of a function or variable.

5. in attitudes research, see complexity of an attitude.