Many of the encounters that people have with apparitions (or ghosts) of the dead take place over a wide range of time, from days, to months, to even years after a person has passed. Often they spontaneously occur when one least expects them to - even at holiday time. Such was the case for a bereaved widow who reported seeing the ghostly figure of her recently deceased husband, as described in her account given in the collection of apparitional experiences gathered by British researchers Celia Green and Charles McCreery in the mid-1970s:
My husband died in August 1970. The following Christmas, 1970, I spend with my married daughter (our only child), her husband and two teen-age children at their home in Bexley Heath, Kent [in England]. This was the first Christmas spent away from my home, my family having previously spent all the holidays with my husband and self at our home in Wimbledon. On Boxing Day, Dec 27th, between 11 o'clock and midnight we were all playing Monopoly and at that time I was not even thinking of my husband. I looked up from my game and my husband was sitting on the settee opposite. This I could not believe. I covered my eyes with my hands and looked again; he was still there. I then for some reason counted the people present and there were six of us, not five. I must have looked very distressed, everyone looked up from the game and enquired what was wrong. I was a little incoherent and wept, and my husband got up from the settee, crossed the room, opened the door, and went out, turning at the last moment, putting his head back inside the door and smiling at me. He appeared as in life (rather unusually dressed for a winter evening), wearing his charcoal coloured trousers and an open necked white shirt. I was overcome with grief and went to bed at once. At no time since have I heard or seen anything else of this nature. [1, pp. 190 - 191]
One thing which is notable from this account is that the woman saw her husband wearing familiar attire, which is consistent with an observation made by parapsychologist Richard Broughton that: "Often the clothing that the ghost appeared in was what the deceased customarily wore." [2, p. 150] This may hint at the possibility that the experience had drawn upon her own memory of what her husband looked like in life. Her experience is also consistent with the observation made by psychical researcher Eleanor Sidgwick that sometimes when a spectral figure appears, only some of the witnesses present in the room may see it, while others may not. [3, p. 145]
Studies suggest that moments in which widows and widowers have reportedly seen, heard, smelled, or felt the presence of their deceased spouse are not uncommon. One of the first studies of this phenomenon was conducted by British physician W. Dewi Rees in 1971, who interviewed 293 widows and widowers in the mid-Wales region of the UK.  Nearly half of them (47%) reported having an experience in the time following their spouse's passing, with visually seeing their spouse being the second most common type of experience they reported (behind simply feeling their presence, which was the most common). Similar results were found in a second study conducted in the U.S. in the mid-1980s.  Although a much smaller number of widows and widowers were interviewed, 61% of them still reported having an experience.  Even in more recent times, a number of experiences continue to be reported. For example, the following account of a sighting was given by a woman who was part of a British widows club in the late 1990s:
I really saw my husband now, about six or seven weeks after. I'd gone to sleep. I'd had a sleeping tablet. I couldn't sleep, and I woke up to hear somebody say, "Lucy, Lucy, Lucy," and I woke up, and it was like I am now, and just inside the bedroom door was John, HONESTLY! And he gave me the loveliest smile, and he'd got his lovely silver-grey suit on, and that was it. Never dreamt about him since or anything. But it was real. It was really real. [6, pp. 143 - 144]
Another woman in the same club described hearing the voice of her husband in this manner:
...sometimes I'll sit here and somebody'll say, "Mary!" And I'll look around, and I thought, 'Well, I've not done it! I've not said that!', you know....About three times....somebody said, "Mary!" And I've thought, 'That's Tom!', you know. Because I know there's nobody else it could be. But that has happened three times. [6, p. 143]
A number of other personal accounts in which widows and widowers described seeing the figure, hearing the voice, smelling the scent, feeling the touch, or sensing the presence of their deceased spouse have also been presented by Icelandic researcher Erlendur Haraldsson in Chapter 16 of his 2012 book The Departed Among the Living.  Rarer forms of experience, in which objects were seemingly moved or other physical events occurred following periods of bereavement, have also been described by American researcher Sylvia Hart Wright. 
As Rees initially noted, these experiences "...are normal experiences after widowhood, providing helpful psychological phenomena to those experiencing them." [4, p. 41] And indeed, the studies tend to indicate that many widows and widowers actually found their experiences to be comforting and beneficial. As Haraldsson points out, one thing "...which is usually apparent in these accounts is that most of these perceptions are experienced with positive feelings. The accounts include descriptive words like: comforting, happiness, help, and strength. Fear is very seldom mentioned and terror is only mentioned in one account." [7, p. 108] This is in line with a broader survey of 582 apparitional encounters conducted by afterlife researcher Dianne Arcangel, who found that 98% of people in the survey found their encounters with deceased loved ones to be comforting, and had the effect of greatly reducing their feelings of grief. [9, p. 287]
It is hoped that people who may be missing a lost loved one during this holiday season will find some level of comfort in these experiences and in the findings derived from the study of them. The PRF would like to wish everyone a bright and pleasant Christmas!
 Green, C., & McCreery, C. (1975). Apparitions. London: Hamish Hamilton Ltd.
 Broughton, R. S. (2006). Why do ghosts wear clothes? - Examining the role of memory and emotion in anomalous experiences. European Journal of Parapsychology, 21, 148 - 165.
 Sidgwick, E. M. [Mrs. H.] (1885). Notes on the evidence, collected by the Society, for phantasms of the dead. Proceedings of the Society for Psychical Research, 3, 69 - 150.
 Rees, W. D. (1971). The hallucinations of widowhood. British Medical Journal, 4, 37 - 41.
 Olson, P. R., Suddeth, J. A., Peterson, P. J., & Egelhoff, C. (1985). Hallucinations of widowhood. Journal of the American Geriatrics Society, 33, 543 - 547.
 Bennett, G., & Bennett, K. M. (2000). The presence of the dead: An empirical study. Mortality, 5, 139 - 157.
 Haraldsson, E. (2012). The Departed Among the Living: An Investigative Study of Afterlife Encounters. Guildford, UK: White Crow Books.
 Wright, S. H. (1998). Experiences of spontaneous psychokinesis after bereavement. Journal of the Society for Psychical Research, 62, 385 - 395.
 Arcangel, D. (2005). Afterlife Encounters: Ordinary People, Extraordinary Experiences. Charlottesville, VA: Hampton Roads Publishing Company.