10 Complex Psychological Mysteries of the Mind

Have you ever stared at the same word for so long that it completely lost its meaning? Or, have you ever walked into a room in your house and felt like you’d never seen it before?

That is just your brain “doing tricks,” so to speak. If you feel like reality is a bit “off,” or a place you’ve known forever seems ordinary and alien at the same time, you are experiencing what some call “mental hiccups.”

This list explores the far reaches of the brain and the illusions it may produce, whether induced or not.

Related: 10 Fascinating Facts About the Human Brain

10 What Exactly Is Jamais Vu?

Jamais vu is the lesser-known counterpart to déjà vu, and it can be unnerving. Some people report that while speaking with close friends, their companion’s face suddenly seems unfamiliar for a few seconds—like they’ve morphed into a stranger. Others walk into a familiar building only to feel like they’ve never been there before.

The phrase means “never seen” in French, and while considered rare, jamais vu is a recognized psychological phenomenon. Experts don’t fully understand what causes it, but one hypothesis suggests that brain pathways momentarily fall out of sync or disconnect, disrupting recognition. A less scientific explanation proposes that lack of attention may lead your brain to process something as unfamiliar, even if you know it well. Either way, it’s a brief but strange blip in perception.^[1]

9 So Then, What Is Presque Vu?

Presque vu is even more frustrating than jamais vu. It’s what happens when you’re in mid-conversation and suddenly can’t recall a word or phrase you’ve used your entire life. You know exactly what you mean, but the word remains maddeningly out of reach. Hence the name: “almost seen.”

Also called the tip-of-the-tongue phenomenon, presque vu is incredibly common—over 90% of people experience it. Psychologists believe it occurs when you retrieve a similar but incorrect word first (like “momentum” instead of “momentary”), which temporarily blocks access to the right one. Thankfully, it’s harmless. And ironically, the more you stress about it, the longer it may take to recall the word. Best advice? Stop trying. Your brain will likely deliver the answer when you least expect it.^[2]

8 The Frequency Illusion Is Not as Real as You Think

Have you ever learned a new word, like “serendipity,” and then suddenly seen it everywhere—on TV, social media, and in books? That’s the frequency illusion, also known as the Baader-Meinhof phenomenon.

It’s not that the word suddenly popped into existence; rather, your brain is on high alert for it. This process is called selective attention. Once your brain decides something is important, it filters for it constantly. Confirmation bias then kicks in—you notice the word again and again and start believing it’s appearing more frequently than ever.

This illusion is harmless, but marketers know how to exploit it. Once you click on a topic, algorithms flood your feed with similar content. You may find yourself obsessing over something you didn’t care about a week ago. The solution? Be aware. Not everything that “seems” frequent is truly new.^[3]

7 Is Precognition a Real Thing?

Precognition—the supposed ability to know the future—remains one of the most controversial phenomena in psychology. It fascinates many people, but scientific consensus dismisses it, largely because it violates the law of causality: an effect cannot happen before its cause.

That hasn’t stopped thousands from claiming they’ve predicted events, whether personal tragedies or global disasters. Experts often attribute these experiences to coincidence, unconscious pattern recognition, or false memories—sometimes tied to déjà vu.

Supporters sometimes cite authors like Jules Verne, who described a moon landing from Florida in his 1865 novel From the Earth to the Moon. While intriguing, this is better seen as imaginative foresight than proof of psychic ability. Science remains firmly skeptical, though stories of accurate predictions continue to capture imaginations.^[4]

6 What About Retrocognition?

Retrocognition is the supposed ability to perceive past events you couldn’t have known about through normal means. Like precognition, it lives in the realm of pseudoscience and paranormal belief.

The most famous example is the Moberly–Jourdain incident. In 1901, Charlotte Moberly and Eleanor Jourdain claimed to stumble upon scenes from the past while walking in the gardens of Versailles. They described odd people, buildings, and landscapes they believed no longer existed. Later, they reportedly found a map from 1783 that showed features matching their descriptions.

Skeptics argue these details could have been remembered unconsciously or reconstructed from historical records. Scientists point out that no controlled way exists to test retrocognition, and therefore its credibility is doubtful. Still, it remains a staple of ghost stories and time-slip tales.^[5]

5 Have You Ever Experienced the Ganzfeld Effect?

Sensory deprivation can play strange tricks on your brain. The ganzfeld effect is one example—it occurs when your senses are limited to the point that your brain starts filling in the blanks. This can result in vivid hallucinations.

For example, staring at a blank-colored wall for several minutes can cause the color to shift and morph before your eyes. If you persist, you might even see shapes or images, similar to effects caused by psychedelic drugs. Parapsychologists have long used the ganzfeld setup to study extrasensory perception, though mainstream scientists remain unconvinced.

Still, it’s one of the few psychological illusions you can induce yourself—no lab needed.^[6]

4 The Illusory Truth Effect

Repeat a false statement enough times, and it starts to feel true. That’s the illusory truth effect, and it explains why myths like “you only use 10% of your brain” still circulate.

Even when someone knows better, repetition makes misinformation more believable. Advertisers use this tactic constantly. If you’ve ever taken vitamin C for a cold despite studies disproving its benefits, you’ve probably been influenced by repetition, not facts.

A 2015 study even showed that people aware of the truth can be swayed by repeated falsehoods. The best way to fight this effect is to fact-check everything—even if it’s something you’ve heard a dozen times.^[7]

3 Is Ganser Syndrome Really a Dissociative Disorder?

Ganser syndrome is rare and strange. People with it may give bizarre or incorrect answers to basic questions—like saying 2 + 2 = 5. They may also experience amnesia, hallucinations, or fugue states. It was first described by Siegbert Ganser in 1898 after observing the behavior in prisoners, which earned it the nickname “prison psychosis.”

There’s still debate about its classification. Some experts believe it’s a dissociative disorder, while others view it as a factitious disorder—symptoms faked for attention or some gain. Since diagnostic criteria are vague, it’s often misdiagnosed or dismissed.

Fortunately, it usually resolves on its own, especially with supportive therapy. But whether it reflects real disconnection or just clever manipulation remains unclear.^[8]

2 The Troxler Effect Is Very Disturbing

You’ve likely seen the animated GIF: a circle of purple dots around a central cross. Focus long enough, and one dot disappears or turns green. That’s the Troxler effect.

It happens because your brain stops responding to stimuli that don’t change in your peripheral vision. But it gets creepier. In a 2010 study, people stared into mirrors in dim light for ten minutes. Two-thirds saw their faces distort, half saw monsters, and more than a quarter saw an unfamiliar person staring back.

Why? Your brain fades out the parts of your face you’re not directly focusing on. It fills in missing information with stored images or fears—like that creepy face from a horror movie. It’s harmless, but if you want to sleep peacefully, maybe don’t try it.^[9]

1 You May Have Experienced Choice Blindness

Choice blindness is a bizarre glitch in how we perceive decision-making. You might choose one item, but if someone switches it out, you may not notice—and even explain why you “chose” the replacement.

In one study, participants were shown photos of two female faces and asked to choose which was more attractive. After they chose, the researchers secretly swapped the photo. Most participants didn’t notice and confidently explained why they found the new (unselected) face appealing. Only 13% spotted the switch.

It turns out we’re far less aware of our choices than we think. But when choices really matter—like a wedding dress with specific details—we’re more likely to catch the swap. Still, it’s a reminder: if you’re justifying a decision, make sure it’s actually the one you made.^[10]