The Stroop effect (sometimes called the Stroop test) is an outcome of our mental (attentional) vitality and flexibility. The effect is related to the ability of most people to read words more quickly and automatically than they can name colors. If a word is displayed in a color different from the color it actually names for example, if the word green is written in blue ink
then we have a hard time noticing the blue ink. In this instance even when asked to name the color of the ink, we tend to say the name the word represents.