What does apperception mean?
The definition of apperception
Ap`per*cep”tion, n.
Etym: [Pref. ad- + perception: cf. F. apperception.] (Metaph.)

The mind’s perception of itself as the subject or actor in its own states; perception that reflects upon itself; sometimes, intensified or energetic perception. Leibnitz. Reid. This feeling has been called by philosophers the apperception or consciousness of our own existence. Sir W. Hamilton.