Why the word wins
Reading is not something a literate adult chooses to do. The word is recognised before attention gets involved, and the answer it suggests is already on its way to your hand while you are still finding the colour. Every item is a small race between an automatic process and a deliberate one, and the automatic one starts earlier.
John Ridley Stroop published this in 1935. The effect is still one of the most reliable in psychology: it survives practice, it works in every language its subjects can read, and it disappears completely for words in a script you cannot read.
The asymmetry with the machine
- A computer has no automatic processes to override: nothing is read unless a line of code reads it, so there is nothing to suppress.
- The same asymmetry runs the other way too — the shortcuts that cost you here are what let you read a page without spelling it out.
- Clinically the test is used to measure exactly this control: how well a person can hold back a habit that fires on its own.