What do you think of this fact?
Try this: the word GREEN is printed in red ink, and you have to say the ink color, not the word. Your mouth wants to say “green”. That tiny stumble is the Stroop effect, and the man behind it barely stuck around to see it become famous.
100 students and a stopwatch
John Ridley Stroop discovered the effect as part of his doctoral thesis at George Peabody College for Teachers. He published it in 1935 in the Journal of Experimental Psychology under the title “Studies of interference in serial verbal reactions”.
In one experiment, 100 college students named the colors of 100 items. When the items were simple colored squares, they needed 63.3 seconds on average. When the items were color words printed in a clashing ink, they needed 110.3 seconds. That is about 74 percent more time, just because their brain kept reading the word.
The reverse barely mattered. Reading the words out loud while ignoring the ink slowed people down by only 2.3 seconds compared with words in black ink, a difference Stroop himself did not consider reliable. Reading is so automatic for you that it barges in, while naming a color takes real effort.
The preacher who walked away
Stroop’s life went in a different direction. He had started preaching at 20 and spent nearly 40 years as a teacher and administrator at David Lipscomb College in Nashville. According to his son Fred, he largely left psychology near the end of his life and devoted himself to biblical studies. He died in 1973 without knowing how big his discovery would become.
Meanwhile, his thesis kept getting cited: by 2014, more than 9,900 times. Vanderbilt psychology professor Daniel Levin called the Stroop task “the most famous task in cognitive psychology”.
Bonus fact: Stroop’s son Fred has a rare inherited form of color blindness, so he cannot experience his father’s famous effect himself.
One of psychology’s best-known tests came from a man whose real passion was somewhere else entirely.