Psychology

In 2005, Yale researchers taught capuchin monkeys to use metal tokens as currency. The monkeys developed gambling and loss aversion spontaneously. Some males exchanged tokens with females for food.

Tears come in three types — basal, reflex, and emotional — with measurably different chemistry. A 1980s study found emotional tears contain more prolactin and manganese than reflex tears, supporting the hypothesis that crying may expel stress-related biochemicals.

In a 2010 Harvard study, IBS patients handed pills labelled "Placebo — inert ingredients" still improved significantly more than untreated patients. The brain responds to the ritual of swallowing a pill even without deception — triggering real neurochemical changes.

Acetaminophen (Tylenol) may relieve social rejection as well as headaches. A 2010 study found three weeks of daily use made social exclusion less distressing, with brain scans showing reduced activity in the same nerve circuits that handle physical pain.

In a 1913 experiment, subjects detected whether someone outside their vision was watching them with only 50.2% accuracy—essentially random chance. Our belief we can sense stares is confirmation bias: we remember the hits and forget the misses.

A baseball outfielder does not calculate where a fly ball will land. They simply run while keeping their line of sight to the ball at a constant angle. Falcons hunting ducks use the same method. This instinctive tracking is called the gaze heuristic.

When asked to match 'bouba' and 'kiki' to a round shape and a spiky shape, about 88% of people worldwide assign 'bouba' to the round one and 'kiki' to the spiky one. Called the bouba/kiki effect, this tendency appears even among speakers of unwritten languages and the congenitally blind.

The urge to squeeze or bite something extremely cute is a real phenomenon called "Cute Aggression." Yale University research found it's a defense mechanism: the brain generates slight negative emotions to counterbalance overwhelming positive feelings — similar to crying tears of joy.