Some of these marginal elements may be so distinctly within the field of awareness that we are conscious of them, but dimly so.[165] Others, in particular cases at least, may be so far outside and hidden in the twilight obscurity that the subject is not even dimly aware of them. In more technical parlance, we may say, they are so far dissociated that they belong to _an ultra-marginal zone and are really subconscious_. Evidence of their having been present can only be obtained through memories recovered in hypnosis, abstraction, and by other methods. These may be properly termed coconscious. Undoubtedly the degree of awareness for marginal elements, i.e., the degree of dissociation between the elements of the content of consciousness, varies at different moments in the same individual according to the degree of concentration of attention and the character of the fixation, e. g., whether upon the environment or upon inner thoughts. It also varies much in different individuals. Therefore some persons lend themselves as more favorable subjects for the detection of marginal and ultra-marginal states than others. Furthermore, according to certain evidence at hand, there is, in some persons at least, a constant shifting or interchange of elements going on between the field of attention and the marginal and the ultra-marginal zone—what is within the first at one moment is in the second, or is entirely subconscious, the next, and _vice versa_. Amnesia develops very rapidly for the contents of the twilight region, as I have already stated, and this renders their recognition difficult.[166] In favorable subjects memory of that portion of the content of consciousness which is commonly called the fringe can be recovered in abstraction and hypnosis. In these states valuable information can be obtained regarding the content of consciousness at any given previous moment,[167] and this information reveals that there were present in the fringe conscious states of which the subject was never aware, or of which he is later ignorant owing to amnesia. I have studied the fringe of consciousness by this method in a number of subjects. A number of years ago _a systematic study_ of the field of the content of consciousness outside the focus of awareness, including not only the fringe but what may be called the ultra-marginal (subconscious) zone, was made in a very favorable subject (Miss B.), and the general results were given in an address on the “Problems of Abnormal Psychology”[168] at the Congress of Arts and Sciences held in St. Louis (1904). I may be permitted to quote that summary here. The term “secondary consciousness” is used in this passage to designate the fringe and ultra-marginal (subconscious) zone.