The human brain is a mystery box. In other words, the brain is so much more complicated than you can imagine. The number of neurons, the underlying cells that make up the nervous system and nervous tissue, is similar to that of stars in the Milky Way; the number of synapses that connect neurons is simply beyond the scope of imagination. Physicist Emerson Pugh said, "If the human brain is so simple that we could understand it, we would be so simple that we couldn't."[1] The human brain is still a subject of study, and yet humans do not fully understand its functions or capabilities. That is probably why most people come across surprising or scary experiences at least once in their lifetime. Some people simply put them as accidental illusions, while others understand them as a spiritual event. Celebrating the upcoming Halloween, CAH will share some spooky psychological effects that you may or may not have heard of or experienced yourself, so follow along!

1. To What Extent Do You Believe in What You Hear and See?

a. Pareidolia

Pareidolia is a psychological response of recognizing a pattern that is completely irrelevant to its content, usually, though not always, visually. Its form varies: misunderstanding a simple crease of clothes in ghost photography as a ghost’s face due to its similarity with a person’s face or identifying a specific message or language from a song or audio recording played in reverse are prominent examples. Another situation is when someone wakes up at night and sees a pile of clothes hanging on a chair or ceiling momentarily appearing to be a person or a monster. What is shocking is that the person experiencing such an illusion feels like the mistaken monstrous figure is either staring or facing them. The impact and the form of this experience greatly vary from person to person, and its trigger is unclear. In general, the experience surprises people, leaving a negative impression. This often happens when people watch horror films or hear scary tales before going to bed. This is because when a person is startled, he or she usually becomes sensitive to the surrounding environment. This allows the person to quickly recognize what seems to be threatening and unusual when he or she wakes up in the middle of the night. But again, the form and the impact of this experience depend largely on the person and some people even happen to see faces in an empty room.

b. Troxler’s Effect

i. What is the Troxler Effect?

Have you ever come across a picture where you stare at a dot or a cross for a short time and notice a change in the picture? That is called the Troxler effect: a phenomenon in which the surrounding shape disappears or changes when you stare at some point for a long time. You may experience the background becoming blurred, seeing an afterimage of the picture, or an illusion of changing color. Figure 1 is a common example of the Troxler effect so go ahead and try it. Staring at the cross mark in the middle for about 30 seconds, you can see the outer periphery of the cat's face vanish. This effect becomes more interesting when it’s done with your face. The method is simple – look into your face through a mirror for about ten minutes in a slightly dark room. Dr. Caputo at the University of Urbino conducted the experiment above and found that 66 percent of the subjects experienced a notable distortion of their faces, 28 percent of them saw someone he or she had never seen before, and 48 percent of them saw a fantastic, monstrous figure[2]. It may appall you for a moment, and the longer you look, the greater the distortion becomes; accordingly, the experiment is not recommended for people unfamiliar with this sort of spooky experience. If you are one of these people, try this instead: scan the QR code (Fig 2) and you will see a picture of a figure. Stare at the figure's nostrils for about 15 seconds and blink rapidly facing a flat wall (white if possible). You will then see an afterimage slightly different from the picture you just saw.

ii. Why Does this Happen?

The human brain only accepts limited information at a time. Specifically, while reading this article, you probably would not feel the touch of your clothes, your heartbeat, or every breath you take (though you’ve probably noticed them now). The reason is that the human brain simply focuses on certain things and does not care as much about other information. The same is true for our vision. As your eyes focus on a particular point, your eyes start to give less attention to information that seems unimportant, creating an effect often referred to as being "blurred.” In detail, the outer surface of the shape assimilates with the surrounding environment, meaning the boundary between in and out becomes vague. This is why when you gaze at our faces for a long time, you will see a face in which its boundaries are out of focus and crushed.

2. Ganzfeld Effect: How Your Brain Can Trick You

The Troxler effect caused an illusion, but would you believe if our brains could actually create hallucinations? What is more, if you can hallucinate by putting yourself in a specific environment, would you like to try it? If not, let’s see if you change your mind as you keep reading. The human brain constantly seeks to receive visual information. That is, the human brain is unfamiliar with situations where sensory signals are cut off. Therefore, when visual stimuli are blocked for a certain period, the human brain produces artificial signals to avoid complete deprivation of the ability to take in visual information, which may appear as hallucinations. Specifically, when visual information is cut off, our eyes slowly experience "fade out" which is a gradual decrease in the perception of brightness.[3] Once human eyes come to the conclusion that there are no incoming visual signals, it artificially creates stimuli to occupy our vision and hearing. The trigger of this experience is not limited to a complete deprivation of light but also available in situations where you can see nothing but white – a severe, blinding snowstorm, for example. Many psychologists and scientists in the past used to give considerable attention to this mysterious effect, expecting it could be a potential clue to finding the sixth sense of seeing or predicting the future.[4] Although the Ganzfeld effect is mostly harmless, its impact varies widely from person to person depending on the duration of experience and the type of hallucination he or she sees.[5] There may even be aftereffects so let’s leave this story just for entertainment.

Many scientists have studied the human brain and have attempted to explain what some people believe as psychic phenomena, and this article briefly introduced three phenomena that many people believe as psychic phenomena or have explored with curiosity. Still, there are so many more experiences that people have that are difficult for others to relate to. It can be an illusion, science, a psychic phenomenon, or even something else. Who knows? Which side are you on?