Don’t read the words on the right–just say the colors they’re printed in, and do this aloud as fast as you can.
You’re in for a surprise!
If you’re like most people, your first inclination was to read the words, ‘red, yellow, green…,’ rather than the colors they’re printed in, ‘blue, green, red…’
You’ve just experienced interference.
When you look at one of the words, you see both its color and its meaning. If those two pieces of evidence are in conflict, you have to make a choice. Because experience has taught you that word meaning is more important than ink color, interference occurs when you try to pay attention only to the ink color.
The interference effect suggests you’re not always in complete control of what you pay attention to.
What do you think would happen:
If you tried this experiment with a very small child who had not yet learned to read?
If you tried this experiment with someone who was just learning to speak English?
If you used the same order of ink colors but wrote non-color words?
If you made up an experiment of your own.
Source: APA Online