Death bed visions occur when a dying person sees spirits who have come to help him make the transition at death. Death-Bed Visions by William Barrett gives many examples of this phenomena. There are known cases where those attending the dying also see the spirits. Chapter 6 of Barrett's book describes an example of this.
A short time before she expired I became aware that two spirit forms were standing by the bedside, one on either side of it. I did not see them enter the room; they were standing by the bedside when they first became visible to me, but I could see them as distinctly as I could any of the human occupants of the room....
Just before they appeared the dying girl exclaimed, 'It has grown suddenly dark; I cannot see anything!' But she recognized them immediately. A smile, beautiful to see, lit up her face. She stretched forth her hands and in joyous tones exclaimed, 'Oh, you have come to take me away! I am glad, for I am very tired.'
As she stretched forth her hands the two angels extended each a hand, one grasping the dying girl's right hand, the other her left hand....
There is also a case of a death-bed vision being confirmed through a medium. It occurred while Richard Hodgson was investigating the medium Mrs Piper. During one sitting, a spirit communicated through automatic writing and explained that she had attended someone on his death bed and had spoken to him using an unusual phrase. A relative of the deceased who was with him at his death-bed was contacted and confirmed that the dying man claimed to have seen the spirit. The relative spontaneously told what the dying man said of the spirit including the use of the unusual phrase given through the medium. An account of this is related in:
A FURTHER RECORD OF OBSERVATIONS OF CERTAIN PHENOMENA OF TRANCE by Richard Hodgson L.L.D. Proceedings of the Society for Psychical Research Vol. XIII. 1898, p 284 - 582
See the foot note on page 378:
The first writing of the sitting came from Madame Elisa, without my expecting it. She wrote clearly and strongly, explaining that F. was there with her, but unable to speak directly, that she wished to give me an account of how she had helped F. to reach her. She said that she had been present at his death-bed, and had spoken to him, and she repeated what she had said, an unusual form of expression, and indicated that he had heard and recognised her. This was confirmed in detail in the only way possible at that time, by a very intimate friend of Madame Elisa and myself, and also of the nearest surviving relative of F. I showed my friend the account of the sitting, and to this friend, a day or two later, the relative, who was present at the death-bed, stated spontaneously that F. when dying said that he saw Madame Elisa who was speaking to him, and he repeated what she was saying. The expression so repeated, which the relative quoted to my friend, was that which I had received from Madame Elisa through Mrs. Piper’s trance, when the death-bed incident was of course entirely unknown to me.
In this case from the Proceedings of the Society for Psychical Research Volume VI p 20-21, four people see the same spirit. A woman on her death bed sees her sister. A woman in the room with her also sees the spirit. Two women outside the room see the spirit pass through the door. All of them recognize the spirit as the deceased sister of the dying woman.
From Miss Pearson, 15, Fitzroy-square, W.C. April, 1888.In this account from the "Journal of the Society for Psychical Research" Volume XI 1903-1904 p 187, two women attending a dying boy see the spirit of his deceased mother also attending to him.
Mrs. John Pearson was in the room, Mrs. Coppinger and myself in the back room; the house lighted up on the landings and, staircases, our door wide open.
About 1 or 2 a. m. on the morning of December 23rd, both Mrs. Coppinger and myself started up in bed; we were neither of us sleeping, as we were watching every sound from the next room.
We saw some one pass the door, short, wrapped up in an old shawl, a wig with three curls each side and an old black cap. Mrs. Coppinger called out, "Emma, get up, it is old Aunt Ann." I said, "So it is, then Aunt Harriet will die to-day." We jumped up, and Mrs. John Pearson came rushing out of the room and said, "That was old Aunt Ann. Where is she gone to?" I said to soothe her, "Perhaps it was Eliza come down to see how her mistress is." Mrs. Coppinger ran upstairs and found Eliza sleeping in the servants' room. She was very awestruck but calm, dressed and came down. Every room was searched, no one was there, and from that day to this no explanation has ever been given of this appearance, except that it was old Aunt Ann come to call her sister, and she died at 6 p.m. that day.
In a separate letter of the same date Miss Pearson adds
"I now remember my aunt saying 'her sister had come for her, for she had seen her.'"
On Sunday evening, June 28th, 1903, about 9 o'clock, I and the sister were standing at the foot of the bed, watching the sick one, who was unconscious, when suddenly I saw the mother distinctly. She was in her ordinary dress as when with us, nothing supernatural in her appearance. She was bending over her boy with a look of infinite love and longing and did not seem to notice us. After a minute or two she quietly and suddenly was not there. I was so struck that I turned to speak to the sister, but she seemed so engrossed that I did not think it wise to say anything.
The little patient grew gradually worse, until on Tuesday evening, June 30th, I was summoned to go at once. When I arrived at the house he had passed away. After rendering the last offices of love to the dear little body, the sister and I again stood, as on the Sunday, when I said, " M--, I had a strange experience on Sunday evening here." She quickly replied, "Yes, mother was here; I saw her." The young girl is not given to fancies at all, and must have been impressed as I was.