The Brain’s Love for the Paranormal

Ghost hunting is an activity that a surprising amount of Americans are highly dedicated to. The belief in ghosts serves more purpose than mere entertainment: many cultures believe in spirits that survive past death to live in another realm. As depicted in the media, such as the famous movie Ghostbusters, ghost hunters use sophisticated technology, like infrared cameras and electromagnetic field detectors, to record or measure spirit activity. Moreover, numerous photos and videos seem to depict ghostly behavior. However, evidence collected thus far has failed to support the existence of ghosts, and scientists have already used reliable research methods to find evidence that ghosts don’t exist. In that case, what is behind inexplicable sounds, images, and other spooky behaviors? Is it possible that they’re all in our head?

The human brain is used to being correct, so our first instinct is to believe what we see, no matter how impractical it may seem. This becomes dangerous when the brain experiences hallucinations, involuntary false perceptions that are just as vivid as real sensations. People can experience hallucinations due to drugs, mental illness, progressive neurological conditions, vision loss, and more. Hallucinations due to schizophrenia are likely caused by an overactive auditory cortex, the part of the brain that processes sound, resulting in the generation of random sounds and speech fragments. Similarly, those with Parkinson's disease generally have an overactive visual cortex, resulting in the brain generating images that don’t actually exist. Research has also shown that activation of the serotonin 2A receptor, which helps regulate the release of the neurotransmitter serotonin, can induce hallucinations. The receptor can be triggered by hallucinogenic drugs or sleep paralysis, which has been shown to have similar effects as hallucinogenic drugs.

Sleep paralysis is a special scenario that can also cause hallucinations. When you dream, your brain uses the neurotransmitter glycine to put the body in a state of paralysis to prevent you from acting out your dreams and possibly getting injured. If you suddenly awake from REM sleep, the glycine-mediated paralysis might still be in effect. During this period, you might experience sleep paralysis, where you wake up during a dream but can’t move your body. During sleep paralysis, people may hallucinate and see, hear, or feel creatures that aren’t there. Hallucinations are, in fact, very common and nearly five percent of the population has reported seeing or hearing things that others don’t.

Scientists are still trying to understand “everyday” hallucinations. Approximately 70 percent of healthy people experience benign hallucinations when they’re falling asleep every day, such as seeing someone on the edge of their bed, hearing someone call their name, or hearing the phone ringing. A plausible explanation is that factors like lack of sleep, trauma, grief, and stress, make the brain more vulnerable to hallucinations by disturbing the relationship between the frontal lobe and the sensory cortex. The frontal lobe is the brain’s headquarters and makes decisions regarding how the rest of the brain works. When these factors are at play, the performance of the frontal lobe decreases, and the sensory cortex has more freedom, leading to hallucinations.

Hallucinations are not the only cause of seeing “ghost-like” behavior. Every day, the brain is overwhelmed with information and organizes it in two ways. The first is bottom-up processing, where the brain absorbs sensory details and sometimes makes meaning out of meaningless details. For instance, the brain might see a puff of smoke and interpret it as the face of a ghost. The second method of processing is top-down, where the brain picks out the most important information to absorb and fills in the gaps. For example, when you mishear the lyrics of a song, it’s usually because your brain chose to miss that information and fill it in with a meaning that wasn’t there. Similarly, when ghost hunters capture sounds that resemble ghosts speaking, the recording is, in actuality, random noise, but the brain knows it’s supposed to sound like words and will fill in the gaps to make it seem as if there are words being spoken.

Furthermore, those with a stronger belief in the paranormal are more likely to experience inattentional blindness, where the brain misses key details due to a state of absorption, and then blame misperceptions on ghosts. There are also patterns concerning groups of people that are more likely to believe in ghosts. Students with higher grades tend to have lower levels of paranormal beliefs. Moreover, those studying in STEM fields are less likely to believe in the paranormal. This is likely because science-oriented students tend to have stronger critical thinking skills, which help them scout out more likely causes for inexplicable experiences than the presence of a ghost.

Ultimately, “ghost hunters” prey on the faultiness of their own brains and perceptions of the world when they collect evidence of “ghost behavior.” But don’t fret—we can still entertain the unknown and the uncertain, especially since they lead to some pretty spooky ghost stories!