Knock-knock.

“Who’s there?” is a common answer, if you’re playing with a 7-year-old but if the knock is for real, you’ll want to peek through a peep-hole or window to see who’s waiting to come in. So what if there’s no one — and nothing — there? Don’t answer it until you’ve read “Presence” by Ben Alderson-Day, Ph.D.

When it’s said that someone has been “hearing voices,” the common assumption is that they suffer from a kind of mental illness; in fact, about 75 percent of sufferers or schizophrenia say they experience auditory hallucinations. Conventional wisdom says that healthy people don’t “hear voices” or see things that don’t exist, but Alderson-Day says that anecdotal evidence points to the contrary.

It’s relatively common, he says, to sense a presence in the room when you’re sure you’re alone, which is a kind of hallucination that’s “been… documented since the beginnings of psychiatry.” Sometimes, though, those hallucinations are “beyond the sense somehow…” in a way that is real but can’t quite be explained.

Ernest Shackleton and his men heard voices during their ordeal in the South Pole in 1914, and other cold-weather endurance explorers have reported the same. Those incidences could be examples of hypoxia, or a lack of oxygen to the brain, but not always. Significantly, they echo many of the tales Alderson-Day’s seen in his research, which “seemed to be about saving and surviving” imminent disaster or a slow catastrophe.

Such voices or phantom sightings could be pareidolia, or seeing things that aren’t present. They could be “spontaneous activation” of the brain, which has to do with the neuron network. Seeing or hearing what’s not there could be a sign of brain damage or an abnormal stimulation of the brain’s electrical current. Some people with dementia and dementia with Lewy bodies claim to see people just on the periphery of sight. Hallucinations can happen in cases of extreme duress or exertion. Stress cannot be discounted.

And then there are the other maybes. Alderson-Day refuses to dismiss the possibility that some phantom voices and sightings really might be phantoms.

Do you believe in ghosts? You don’t have to, if you read “Presence.” You only need an open mind and a desire to understand science; a belief in spirits is just icing on the cake.

Here, author Ben Alderson-Day, Ph.D.asks readers to be on solid ground with a willingness to suspend disbelief once in awhile, beginning with a knee-jerk reaction and an armchair diagnosis of mental illness. On that, readers are quickly pulled away from the stereotype with reassurance and facts. Remember: this is a science book first and science says aural and visual phantoms are surprisingly common.

Still, there are things that can’t be explained and that’s when this book takes a quick two-step into the supernatural — not in a spooky way, but wide-eyed: we don’t know what we don’t know, so it could have an otherworldly reason. Says Alderson-Day, it obviously needs further study in mind-body medicine. Until then, keep looking, read “Presence,” and wonder… Who’s There?

By Terri Schlichenemeyer

“Presence: The Strange Science and True Stories of the Unseen Other” by Ben Alderson-Day, Ph. D.
c.2023, St. Martin’s Press
$28.99
304 pages