From Scientific America
Ghost Stories:Visit from the Deceased, After a loved one dies, most people see ghost
By Vaughan Bell

In a fascinating article, Vaughan Bell explains that hallucinations are a normal part of grieving.

“The dead stay with us.” They remain in our hearts and minds. They linger in our senses, as sights, sounds, smells, touches or presences.

Hallucinations are a common part of mourning. A study by the researcher Agenta Grimby at the University of Goteborg in Sweden found that 80 percent of elderly people experience hallucinations associated with their dead partner one month after bereavement. The visions can be so vivid that almost a third of the people reported that they spoke in response to their experience and that some of them evoked the very essence of the deceased.

Few are likely to experience grief without re-experiencing the dead. We often fall back on the catch all “ghost” while the reality is in many ways, more profound. Our perception is so tuned to their presence that when they are not there to fill that gap, we unconsciously try to fill it.

On his blog mind hacks Bell says that though the phenomenon is common, most don’t talk about their experiences because they worry about what others might think. You should read the whole article, and don’t skip the comments section. A lot of people don’t accept this explanation at all. I especially liked the story of the ghost dog who brought his master’s walking cane.