New Study Shows It's Surprisingly Easy to Make People Have Auditory Hallucinations

iStock
iStock

If you’ve ever heard something that wasn't there—an auditory hallucination—you know that the sound seems very, very real. A new study suggests that it's easy to induce auditory hallucinations in people, but it's even easier in people who already claim to hear things that aren't there. The research was published in the journal Science.

Co-author Al Powers is a psychiatric researcher at Yale. Speaking in a study, he said hallucinations “…may arise from an imbalance between our expectations about the environment and the information we get from our senses.”

In other words, he says, "You may perceive what you expect, not what your senses are telling you."

Powers and his colleagues recruited 59 people to help them test that hypothesis. There were four groups of participants: people who heard voices and had been diagnosed with psychosis; people who had been diagnosed with psychosis but didn’t hear voices; people who heard voices but had not been diagnosed with any mental illness (we'll come back to that in a moment); and people who just plain didn't hear voices.

The third group was an unusual one: 15 self-professed psychics. These participants said that they heard voices every day, but unlike people in the first group—those diagnosed with psychosis who heard voices—they weren't bothered by the voices they claimed to hear. In fact, they took them to be communications from supernatural forces or entities.

All the participants then underwent brain scans. While they were in the scanner, the researchers used a combination of sounds and images to trick their brains into producing auditory hallucinations. First, participants were shown a checkerboard and played a sound. Then they were told to listen for the sound. Sometimes it played when the checkerboard appeared. Sometimes it didn't play at all, but the checkerboard showed, which led their brains to expect the sound would be played.

Members of all four groups experienced the hallucinations, hearing noises even in the silence. Their brain scans showed that they really were "hearing" the nonexistent sounds.

Unsurprisingly, the two groups of hallucination-prone people were more susceptible to hearing things. But when they were told that there had in fact been no sound, people with psychosis were less likely to believe it. 

The authors say this difference could potentially help doctors spot, diagnose, and treat psychosis in their patients before it becomes severe.

Not-So-Fancy Feast: Your Cat Probably Would Eat Your Rotting Corpse

Tycson1/iStock via Getty Images
Tycson1/iStock via Getty Images

Cat enthusiasts often cite the warmth and companionship offered by their pet as reasons why they’re so enamored with them. Despite these and other positive attributes, cat lovers are often confronted with the spurious claim that, while their beloved furry pal might adore them when they’re alive, it won’t hesitate to devour their corpse if they should drop dead.

Though that’s often dismissed as negative cat propaganda spread by dog people, it turns out that it’s probably true. Fluffy might indeed feast on your flesh if you happened to expire.

A horrifying new case study published in the Journal of Forensic Sciences offers the fresh evidence. The paper, first reported by The Washington Post, documents how two cats reacted in the presence of a corpse at Colorado Mesa University’s Forensic Investigation Research Station, or body farm, where the deceased are used to further forensic science for criminal investigations.

The study’s authors did not orchestrate a meeting between cat and corpse. The finding happened by accident: Student and lead author Sara Garcia was scanning surveillance footage of the grounds when she noticed a pair of cats trespassing. The cats, she found, were interested in the flesh of two corpses; they gnawed on human tissue while it was still in the early stages of decomposition, stopping only when the bodies began leaching fluids.

The cats, which were putting away one corpse each, didn’t appear to have a taste for variety, as they both returned to the same corpse virtually every night. The two seemed to prefer the shoulder and arm over other body parts.

This visual evidence joins a litany of reports over the years from medical examiners, who have observed the damage left by both cats and dogs who were trapped in homes with deceased owners and proceeded to eat them. It’s believed pets do this when no other food source is available, though in some cases, eating their human has occurred even with a full food bowl. It’s something to consider the next time your cat gives you an affectionate lick on the arm. Maybe it loves you. Or maybe it has something else in mind.

[h/t The Washington Post]

Wolf Puppies Play Fetch, Too, Study Finds

Christina Hansen Wheat
Christina Hansen Wheat

It took thousands of years of selective breeding for wolves to become the Golden Retrievers you see at dog parks today. Domesticated dogs are very different from their wild counterparts, but according to a new study, they may have a surprising trait in common. Researchers found that some wolf puppies are willing to play fetch with total strangers, suggesting that following human commands is intrinsic to canines.

For their study in the journal iScience, researchers from Stockholm University in Sweden set out to find how domestication affects behaviors in young wolves. They raised litters of wolf and dog pups separately from 10 days old and placed them in various scenarios.

When the scientists tested how the wolf puppies would respond to a game of fetch, they expected to be ignored. Chasing a ball and bringing it back requires understanding human commands and obeying them—abilities that were thought to only have emerged in dogs post-domestication.

The first two wolf groups met expectations by showing little interest in the toy, but something different happened with the third set. Three eight-week old pups went after the ball and brought it back when they were encouraged to do so. This was the case even when the person giving the commands was someone they had never met before.

Even though most of the puppies didn't play fetch, the fact that those who did belonged to the same litter indicates a "standing variation" for a retrieving trait in wolves. "When you talk about a specific trait in the context of standing variation, it means that there is variation for the expression of this trait within a given population," co-author Christina Hansen Wheat tells Mental Floss. "For our study it suggests that, while probably rare, standing variation in the expression of human-directed behavior in ancestral populations could have been an important target for early selective pressures exerted during dog domestication." In other words, ancient people seeking to domesticate wolves might have focused on some wolves' innate ability to follow human commands.

The first dogs were domesticated as far back as 33,000 years ago. Over millennia, humans have selected for traits like loyalty, friendliness, and playfulness to create the modern dog, but these new findings could mean that the dog's earliest canine ancestors were genetically predisposed toward some of these behaviors.

"All three litters were brought up under identical and standardized conditions across years," Hansen says of the pups in the study. "With this significant effort to control the environmental conditions, it is likely that the differences in behavior across litters to some extent have a genetic basis."

After raising the dog and wolf litters for three years and completing that part of their study, the researchers will continue to analyze their data to see if there are any other adorable (or weird) traits the two groups share.

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