Los Angeles resident Robert Jackson [not his real name] tells the story of a boarder who apparently never left the premises he was renting.

The problem was, he had died many years before.

Jackson’s in-laws bought the property in the early 1980s. It had originally been owned by the local Catholic Church and made into a home for nuns. His wife’s parents immediately turned the property into a boardinghouse and began taking in male boarders.

In 1983, one of the boarders died and, curiously, Jackson said, beside himself none of the family members remembered or ever spoke of the boarder. Of course, Jackson thought that was strange. The man was not easy to forget since he was wheelchair-bound and a dapper dresser.

On the other hand, Jackson felt the collective memory loss may have had something to do with the fact that the boarder was an inveterate complainer who constantly charged that someone was taking his things and that nothing was safe in the house. Although the family knew this was not true, it was an annoying habit that bothered the family and other boarders. However, over time the family learned to ignore the elderly man.

The boarder had another annoying habit. He liked being noticed, and he jumped into other people’s conversation without being invited, often boring into their personal business.

Around the holiday season in 1984, the family turned the home into a private residence, and on any given weekend you could usually find most of the family gathered there–the elderly parents, their children and their grandchildren.

But, according to Jackson, there were always strange goings-on in the house. And there was a standing joke among the younger family members about an unofficial houseguest that was believed to reside in the front bedroom. But the owners, sweet senior citizens both, refused to accept such an idea.

Damelle, 30, a grandson who suffers from sickle-cell anemia, said he first encountered the apparition around 1986, when he was 6 or 7. The incident happened on a weekend when the house was filled with people, as it usually was on the weekends.

The youth, while in the company of several other preteens, started laughing, as if he might have been watching one of the world’s funniest comics. Of course, he captured the other youths’ attention, and they ran to him trying to discover what caused such an outburst of laughter.

“What’s so funny, Damelle?” they asked.

Between giggles, Damelle turned the question on them, “What’s wrong with you guys? Don’t you think the man is funny?” He pointed to the center of the room.

“He keeps making funny faces and playing with me,” said Damelle. “How come you guys are not laughing?”

Damelle pointed again. “Look, he’s so funny,” he said.

When the laughter subsided, a female cousin asked Damell if the man was still there.

“No,” Damelle said. “He went to the back of the house, towards a bedroom.”

Jackson remembers that there was a conversation among the adults surrounding the incident, conducted in such a way as to keep the grandchildren from knowing what was being said, but a few of the adult relatives felt the so-called sighting was a result of Damelle’s sickle-cell medication.

Later there would be similar incidents.

Jackson said the second and third contacts with the aberration took place years later, in 2001, and was witnessed by two family members: his wife, Sarah, a 40-year-old corporate executive, and a 14-year-old niece, Judy. Sarah believes she encountered the “boarder” while she was resting in the guest bedroom, recovering from a medical procedure that required isolation and rest. A cancer survivor, she had ingested a low dosage radioactive tracer and was told to avoid contact with young children. The guest bedroom at her parents’ house has its own bath and is isolated from the other rooms. It provided an ideal location to rest while the tracer’s radioactivity dissipated.

Sarah did not want to take any chance spreading the contamination to her children, who could have been impacted by the radiation, so she chose to spend time at her parents’ until the medication radioactivity wore off. One day around noon she informed her husband who was visiting her that “the houseguest was busy today.”

“What do you mean?” he asked

Sarah said she had been asleep and was awakened by someone throwing or moving her personal items on the dresser and yelling “your s–t ain’t safe here! Someone has been going through your s–t! “In her groggy state, she clearly heard the angry voice, but saw no one. She said she thought she was asleep during the disturbance until she overheard her parents minutes later asking Judy what was wrong?

Upon hearing the commotion, she arose and walked into the living-room to find out what had happened to Judy. Her niece told her she had been in her grandfather’s study doing a homework assignment and saw what appeared to be a man’s legs standing beside the desk. She said she could only see the “legs and shoes.”

According to an aunt, Inez, this gentleman paid a visit to the guest bedroom first and then traveled to the study at the rear of the house. Inez said both grandparents claimed they did not see anything, but they would have been in the path of anyone traveling to the study. She says the grandparents knew something was wrong by the speed at which their granddaughter walked to the living room and sat down quietly with a look of bewilderment on her face.

Jackson said he did inform Sarah, his wife, that the medication she was taking for trigeminal neuralgia–Tegretol–had a history of causing hallucinations and he remembered Sarah responding, “Is Judy taking Tegretol, too?”

Jackson also remembered asking his wife if any of her items appeared to be rearranged on the dresser, but she was not sure.

Jackson said that a fourth sighting took place in 2002 and was witnessed by a 6-year-old grandson who was standing in the same area as his cousin, Damelle, had stood during his sighting around 1986.

The 6-year-old pointed to the same area that his cousin had some 16 years before. As he pointed, he told his mother, who was present in the living room with him, “That man is funny.” Jackson remembers that the grandparents were present and ignored the statement. He said the aunts and the boy’s mom all laughed, and there was no discussion afterward.

According to Jackson and Inez, there has not been a sighting of the gentleman since.

Joe Nikell, Ph.D., professor of literary investigation and folklore at the University of Kentucky and senior research fellow for the Committee for Skeptical Inquiry, has investigated paranormal activity for more than 30 years. After being told of the Jackson family incident, his response was that it was “interesting and describes some of the kinds of apparitions (ghostlike figures) that people experience. It was important to realize that science has never authenticated a single ghost, he said.

“In fact, once the brain is dead, brain activity ceases, so the ability of an imagined ghost to walk or talk would be nonexistent. Also, any energy given off by the body would dissipate, so the idea of finding a ghost hanging out somewhere would be on a par with searching for a light long after a light bulb has burned out. Science regards belief in ghosts as a superstition.”

But how do we explain witnesses’ perceptions of ghostly phenomena?

Nikell said some children experience imaginary “ghosts” much as they might have an imaginary playmate. Some adults, who are said to have fantasy-prone personalities, can also have very vivid encounters. Sometimes, ordinary folk wake up to see an apparition, but they are only having a “waking dream,” a type of simple hallucination that occurs during the trance-like state between sleep and waking.

Similar experiences can occur when one is tired, daydreaming, performing routine chores, or on medication, noted Nikell. Basically, such images spring up from the subconscious and are briefly superimposed on the visual scene–a trick of the mind. For example, ask adults who have driven a car down a poorly illuminated highway by themselves if they ever for a split second thought they saw someone in the back seat, a very common hallucination individuals’ experience.

The above encounter at Jackson’s in-law’s home has an interesting mix of individuals who may believe what they heard or saw, but Nikell cautioned that we must take the following into consideration: three of the individuals at the time of the different sightings were ages 6 and 14 years old, both ideal ages to believe you are seeing ghosts. Two of the individuals involved were on medication; the adult was taking Tegretol and the 6-year-old was taking medication for sickle-cell anemia.

Tegretol is known to cause hallucinations in some individuals, and it is not clear what type of medication the 6-year-old was taking. In reference to Judy, can you imagine how many 14-year-olds tell each other ghost stories? Nikell asked.

Nikell was asked how he explained paranormal documentaries showing ghost-chasers with high-tech equipment catching orbs, measuring temperature gradients, and monitoring electronic voice phenomenon.

“Those guys are actors,” he said. “If physicists accompanied, them they would be proven wrong. There was one episode that was replayed on a monitor after one of the actors claimed a ghost slapped a camera out of his hand. After it was reviewed, he had to admit that he threw the camera as opposed to a ghost slapping it from his hand.

“I believe such phenomena are at the root of the sightings in Robert Jackson’s in-laws house,” he said. “Whatever the actual facts, the least likely explanation is that a ghost is responsible. Still, we must acknowledge that such experiences can seem quite real to the persons having them, and they are nothing to laugh at; indeed, they tell us much about ourselves and the real, natural world we live in.”

What about Ouija boards? How do you explain the mechanics of its operation?

“It’s a simple ideo-motor response,” Nikell said. “In November 2010, I believe the department of psychological sciences at Purdue University published a review of the contemporary ideo-motor theory and, in layman’s terms, when you sit down in front of a Ouija board with a friend, both of you have a dominant idea implanted in your brain about what is going to happen. Muscular movement is based on dominant ideas you already have. In other words, the movement is based on the idea or thought rather than some outside entity moving the pointer on the board.”

John Cree, an African American parapsychologist, is currently marketing an African American themed “Ghost Hunter in the Hood” documentary. He thinks Robert Jackson’s in-law’s home is actually experiencing paranormal activity. He believes it is a cop-out to blame medication. “All the activity chronologically spells ghost,” he said.

A poll conducted by Associated Press in 2007 found that 34 percent of Americans believe in ghosts. The poll also found that 20 percent of African Americans and Hispanics believe in ghosts, as do 17 percent of Whites.

In 2010, when various ethnic groups were polled on folklore by the American Literature Society, it was discovered that most Hispanics are familiar with La Llorona, “The Weeping Woman,” remembered by most Whites as “Bloody Mary,” which can be traced back through English folklore.