The Hering theory is a three color theory. Helmholtz' theory of hearing is that different cells respond to different frequencies of sound. Boring calls Aristotle the father of experimental psychology. Weber discovered that sensation could be quantified. Weber discovered that in order to detect a noticeable difference in stimulation, the change would have to be a constant fraction, not a constant amount.
Apperception is the focusing of the mind on one aspect of the conscious field.
Motor refers to muscle movements. Focusing on the sensory part of an act produces a shorter reaction time. Ebbinghaus made major contributions to the psychology of sensation. Nonsense syllables were constructed to eliminate similarities in word sounds. The greatest amount of forgetting would appear to occur during the semester rather than at the end of a semester.