1. Making words lose their meaning when you repeat them too many times.
“Semantic satiation” is the name for when you repeat a word so many times it sounds like nonsense. The phenomenon was being talked about scientifically as early as 1919, when a paper was published that tried to determine the number of times a monosyllabic word had to be repeated for it to lose its meaning.
2. Making it harder to spot your own typos.
When reading, your brain doesn’t focus on every letter but instead takes in whole words. That’s why you can usually read words even when only the first and last letters are in the right places, lkie tihs. It makes reading much quicker, but a side effect is that spotting typos in your own work becomes much harder, because you’re so familiar with it.
One way to get around this is to make it less familiar – try changing the font or printing it out, for example.
3. Helping you remember things that didn’t actually happen.
“False memories” are surprisingly easy to plant. In a simple lab test, psychologists gave people a list of words related to sleep (bed, rest, awake, etc) but didn’t actually include the word “sleep” itself. Later, when asked to recall the list, participants mistakenly remembered the word “sleep” as often as they did words that were actually on the list.
This phenomenon is why its easy for witnesses of a crime to remember things that didn’t happen. But authors of the sleep-words study see false memories as part of what makes humans clever: “The fact that such inferences can lead one astray … is a small price to pay for the inventiveness of the human mind.”
4. Making you believe horoscopes are specifically about you.
There’s something called the Forer effect, which is named after the psychologist who discovered it.
Bertram Forer told his class he was giving everyone a statement about themselves to read. The class marked the statements for accuracy, giving them 4.26 out of 5 on average. Then – shock horror – he revealed afterwards that all of the statements were the same.
They said things like, “You have a great need for other people to like and admire you,” and, “While you have some personality weaknesses, you are generally able to compensate for them,” which, when you think about them, could apply to most people while still managing to sound specific. These statements are basically how horoscopes manage to sound scarily accurate for lots of people.
5. Getting songs stuck in your head.
According to Vicky Williamson, a music psychologist quoted by the BBC, anything from repeated exposure to a song to having a person, situation, or feeling trigger the memory of a song can cause it to get lodged firmly in your head.
Williamson and her colleagues found that most people just accept their “earworm”. But some people try to get rid of it by listening to the full song, or listening to something else. In fact, the study found that some people had discovered a specific song (one respondent called it a “flush song”) that could cure their earworm without itself getting stuck in their mind.
6. Making you see, hear, smell, and taste things that aren’t there.
You can hallucinate with any of your senses, not just vision. The only criterion for classing something as a hallucination is that you experienced it without an external stimulus. And hallucinations are much more common than you think.
According to one study of nearly 5,000 people in 1996, just over a third of people experience hallucinations before going to sleep. One in eight people get them as they’re waking up.
Hallucinations are more common in people with sleep disorders like insomnia and people with mental illnesses. But not all hallucinations are related to mental illness, and hallucinations relating to smell and taste are most common.
7. Letting the colour of food and drink affect how it tastes.
By adding food colouring to white wine, scientists have been able to fool people into thinking they were drinking red wine instead. (The BBC conducted a similar, if less scientific, experiment for a documentary.)
And it’s not just wine. If you get people to eat dyed-blue steak in the dark, and then turn the lights up, “some will get up and be sick straight away,” Charles Spencer, an Oxford University psychologist told the Guardian.
8. Making you feel actual pain when you see other people get hurt.
Seeing someone else in pain activates areas of your brain associated with the emotional components of pain. But a significant minority of people actually feel pain when seeing someone else get hurt, according to a 2009 study in the journal Pain.
9. Ignoring information it thinks doesn’t matter to you.
While looking at a swirling pattern of blue dots on top of a background of static yellow ones, the yellow dots will disappear from view. This effect is called motion-induced blindness. You should be able to see it for yourself in the illusion above – keep staring at the flashing green dot and see what happens.
It might be due to a fight between the brain’s two halves. Neuroscientist Jack Pettigrew told Nature that the left side of the brain tends to disregard information that doesn’t fit with its view of how the world should be, while the right sees things as they really are.
10. Looking for patterns where none exist.
A 2008 study published in the journal Science found that participants were more likely to see images in TV static, for instance, when they felt a lack of control. After completing affirmation exercises intended to make them feel less helpless, participants were better at seeing the world how it really was.
11. Making you think others’ ideas are your own.
Cryptomnesia is when a memory is hidden from your consciousness. Sometimes those hidden memories can resurface without you knowing where they came from in the first place.
It can lead you to repeat a story back to the person who told it to you in the first place, or even to accidentally plagiarise someone else’s idea because you mistakenly think you came up with it yourself.