His team first gave 19 volunteers descriptions of four imaginary people they were told were real. Each of these characters had different personalities. Half the personalities were agreeable, described as liking to cooperate with others; the other half were less agreeable, depicted as cold and aloof or having similar traits. In addition, half these characters were described as outgoing and sociable extroverts, while the others were less so, depicted as sometimes shy and inhibited. The scientists matched the genders of these characters to each volunteer and gave them popular names like Mike, Chris, Dave or Nick, or Ashley, Sarah, Nicole or Jenny…

The scientists discovered that each of the four personalities were linked to unique patterns of brain activity in a part of the organ known as the medial prefrontal cortex. In other words, researchers could tell whom their volunteers were thinking about.

“This is the first study to show that we can decode what people are imagining,” Spreng says.