If we turn to the mechanism of hallucinations, we shall find that—like dreams—some are apparently originated by the condition of the bodily organs; others again appear to be mere automatic reverberations of recent sensation; whilst yet others cannot be referred to any immediate external stimulus, and suggest the "spontaneous" activity of the higher cerebral centres. With the rudimentary hallucinations—singing in the ears, sparks and flashes of light, etc.—which are caused by transient conditions of the external organs of sense, we are probably all familiar. But experience shows that a small nucleus of actual sensation may enter into more fully developed hallucinations. Thus, to take the simplest case, it is known that "sparks" may develop into "Faces in the Dark," which are themselves on the border-line between mind's-eye pictures and hallucinations. (See St. James's Gazette, "Faces in the Dark," Feb. 10, 1882, and Proc. S.P.R., vol. iii. p. 171.) And in another recorded case (Proc. S.P.R., vol. i. pp. 102, 103) an artist was accustomed to see constantly at his studio the figure of a man, under circumstances which strongly suggest that a point de repère was furnished by those floating motes in the eyeballs which are liable momentarily to cloud the vision when the position is abruptly changed after a period of immobility. And we find cases where the constructive impulse has so amplified and misinterpreted the data of normal sensation that we hardly know whether to class the result as hallucination or illusion. Thus, in a case given in Phantasms (vol. ii. p. 28), a young girl sees the face of a friend growing out of a yellow pansy; and an account of a similar incident has recently been furnished to me by Mr. H. Smith, of the Central Telegraph Office. The reference in the first line of the following narrative is to a rumour of the house being haunted, the remembrance of which possibly gave a definite form to the apparition:—
HALLUCINATIONS CLASSIFIED ACCORDING TO THE SENSE AFFECTED AND ACCORDING TO THE KIND OF PERCEPT.
| (1) | (2) | (3) | (4) | (5) | (6) | |||||
| —— | Realistic Human Phantasms | |||||||||
| of living people.[102] | of dead people. | unrecognised. | Incompletely developed apparitions. | Visions (i.e., scenes or pictures. | Angels and religious phantasms. | |||||
| Visual | 296 | 105 | 272 | 120 | 18 | 10 | ||||
| Visual and Auditory (vocal) | 30 | 41 | 10 | 1 | — | 1 | ||||
| Visual and Auditory (non-vocal) | 7 | 4 | 24 | 13 | 3 | — | ||||
| Visual and Tactile | 13 | 7 | 4 | 5 | — | — | ||||
| Visual and Auditory (vocal) and Tactile | 5 | 6 | 4 | 2 | — | 1 | ||||
| Visual and Auditory (non-vocal) and Tactile | 1 | — | 1 | 2 | — | — | ||||
| Auditory (vocal) | 172 | 57 | 144 | — | — | 4 | ||||
| Auditory (vocal) and Tactile | 6 | 4 | 1 | — | — | — | ||||
| Tactile | 6 | 8 | 55 | — | — | — | ||||
| Tactile and Auditory (non-vocal) | — | — | 5 | — | — | — | ||||
| Total | 536 | 232 | 520 | 143 | 21 | 16 | ||||
Note
Table Continued
| (7) | (8) | (9) | (10) | (11) | (12) | (13) | (14) |
| Grotesque, horrible or monstrous apparitions. | Animals. | Definite inanimate objects. | Lights. | Indefinite objects or touches. | Insufficiently described for classification. | TOTALS | |
| 23 | 22 | 10 | 14 | 14 | 8 | 912 | 1120 |
| 1 | — | — | 2 | 1 | — | 87 | |
| 7 | 3 | 3 | 1 | 2 | — | 67 | |
| 2 | — | — | — | — | — | 31 | |
| — | — | 1 | — | — | — | 19 | |
| — | — | — | — | — | — | 4 | |
| — | — | — | — | — | — | 377 | 388 |
| — | — | — | — | — | — | 11 | |
| — | 2 | 2 | — | 35 | — | 108 | 114 |
| — | — | — | — | 1 | — | 6 | |
| 33 | 27 | 16 | 17 | 53 | 8 | 1622 | 1622 |
NOTE.—This Table does not include 510 cases, of which the details are given at second-hand in 320, and are not given at all in 190.
"POST OFFICE, 3rd Dec. 1892.
"I had a turn last night, and for the moment thought I had caught the spook of my predecessor, but, alas! it all ended in smoke instead of spook. It gave me a turn, though, and made cold water run rippling down my back. It happened thus:—I had paid a good-night visit to the room of a dear little friend, a Callithrix monkey, whose lodgings are in a side building which has a door opening into the entrance hall. There was no light in the room of my friend, but a side light shone in through the door from the hall. (I was smoking.) On going out I looked back before shutting the door, and was startled to see just behind me, in the dark shade, the face of a human being—apparently an old man with grey hair. The face was perfectly distinct in every detail for an appreciable interval, and the eyes seemed to look sadly at me, and I looked sadly at him. The face moved, and the appearance, though a bit out of shape, still remained. I, however, saw what it was, and gave a gasp of relief which blew the old man's countenance into the shapelessness of the last remains of an extra strong puff of tobacco smoke I had left behind me."