In life, stupid people overestimate how competent they are at something, whereas smart people tend to sell themselves short. This is backed up by a Cornell University study conducted by psychologists David Dunning and Justin Kruger, who managed to establish the Dunning-Kruger effect, a phenomenon that proves the above statement. Here are 10 subtle signs that are considered to be hallmarks of intelligence:
1. You took music lessons
A 2011 study showed that verbal intelligence among 4 to 6-year-olds rose significantly after just a single month of taking music lessons. Furthermore, a 2004 study showed that 6-year-olds that took nine months of keyboard or voice lessons experienced an IQ boost when compared to those that didn’t take those lessons. Yet another study, this time conducted in 2013, suggested that high-achieving kids were more likely to take music lessons. In real-world terms, this means that music can enhance pre-existing cognitive differences.
2. You’re the oldest
Older siblings tend to be smarter, but that isn’t down to genetics. A study of 250,000 18 to 19-year-old men conducted by Norwegian epidemiologists found that the average firstborn had an IQ of 103, the second child had an IQ of 100, and the third child had an IQ of 99. This is attributed to the psychological interplay of parents and children.
3. You’re thin
A 2006 study conducted on some 2,200 adults over a five-year period found a correlation between waistline size and cognitive ability. Another study found that 11-year-olds that scored low on both verbal and nonverbal tests were found to be more likely to be severely overweight by the time they got to 40. Researchers believe that higher intelligence would have led them to seek better-paying jobs in their future lives, thus avoiding having a low income and not being able to take care of their health as well.
4. You’ve used recreational drugs
A British study conducted on 6,000 British people born in 1958 found a correlation between high IQs in childhood and recreational drug use in adulthood. The participants, who were all born in 1958, were tested aged 11 and again aged 42. Those with higher IQ scores in childhood were shown to have a greater likelihood of using certain illegal substances in their adult lives.
5. You’re left-handed
Although left-handedness used to be associated with criminality in the past, no-one has been able to say whether this is actually true. Most research points to the notion that left-handed people are more “divergent thinkers” than right-handed people are. In other words, they’re more capable of coming up with novel ideas after being prompted to do so.
6. You’re tall
A study conducted at Princeton University back in 2008 showed that taller individuals scored higher on IQ tests when they were children, and earned more money in adulthood. This was found to be true even before schooling had had a chance to play a role in their lives.
7. You drink alcohol regularly
Satoshi Kanazawa, an evolutionary psychologist, found that adults who scored higher on IQ tests when they were kids drank more alcohol more frequently in adulthood than those that scored lower.
8. You learned to read early
Some 2,000 pairs of identical twins participated in a UK study, which showed that the sibling who learned to read earlier tended to show higher cognitive ability on tests. The study also suggested that learning to read from an early age increases both verbal and nonverbal reasoning ability.
9. You worry a lot
Anxious individuals may be smarter than other individuals in a certain way. One study, which involved questionnaires being handed out to 126 undergraduate students, showed that people who tended to worry and ruminate a lot scored highly on measures or verbal intelligence. On the other hand, people who didn’t do much worrying or ruminating scored lower on nonverbal intelligence tests.
10. You’re funny
Some 400 psychology students took intelligence tests to measure their abstract reasoning abilities and verbal intelligence. They were asked to come up with captions for cartoons, which were then reviewed by independent raters. As predicted, it was the smarter students that elicited the most laughs.
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