Stroop Test

The Stroop effect, first published by John Ridley Stroop in 1935, is one of the best known findings in cognitive psychology. When you see the word "RED" printed in blue ink and have to name the ink, your automatic reading response competes with the colour-naming response, and you slow down.

Reading is more automatic than colour naming for literate adults, so the brain has to use executive control to suppress the word and attend to the ink. The size of that delay varies between people and is affected by age, attention and some neurological conditions.

Clinical neuropsychologists use the Stroop test to assess executive function, in particular inhibitory control and cognitive flexibility. A larger Stroop effect is associated with ADHD, depression, schizophrenia and several forms of dementia, and the test appears in many brain-injury assessment batteries.

Brain imaging links the task to the anterior cingulate cortex and the dorsolateral prefrontal cortex, regions involved in monitoring conflict and exerting control. Practising Stroop-like tasks improves performance on them; how far that transfers to everyday thinking is still debated.