CHAPTER XIII.

DISCRIMINATION AND COMPARISON

Locke on discrimination. Martineau _ditto_. Simultaneous sensations originally fuse into one object. The principle of mediate comparison. Not all differences are differences of composition. The conditions of discrimination. The sensation of difference. The transcendentalist theory of the perception of differences uncalled for. The process of analysis. The process of abstraction. The improvement of discrimination by practice. Its two causes. Practical interests limit our discrimination. Reaction-time after discrimination. The perception of likeness, 528. The magnitude of differences. The measurement of discriminative sensibility: Weber's law. Fechner's interpretation of this as the psycho-physic law. Criticism thereof.