With practice, some activities can become automatic--combining many actions into one, and so using less attention. Reading is one example of this. Once you have started to read a word, you can't stop in the middle, and you can't prevent yourself from reading a word that you see. Driving is another example; you don't need to consciously think about the movements you make while driving. Automatic actions are completely routine and are generally less affected by interference, suggesting that they take much less attention to carry out than other activities. Automaticity increases with practice; thus, novice drivers are more easily distracted than people who have been driving for years.

One example of automaticity that is used often in psychology experiments is the Stroop task. In the Stroop task, subjects are shown a series of words, one at a time. Each word is printed in a different color ink, and the subject's task is to say the color of the ink as quickly as possible. For words that are not related to color, this task is relatively easy. However, when the word printed is the name of a color, such as "blue" or "red," that conflicts with the color of the ink (e.g. the word "blue" printed in green ink), subjects respond significantly more slowly. Their lower reaction times show that something is interfering with the color-naming task. Subjects must be reading each word that appears, rather than just looking at the color of the ink. If they were able to look at the ink color without reading the word, then there would be no increase in interference, since it would not matter what the word said. Since their performance is disrupted more for color names than for any other words, the Stroop task provides good evidence that reading is automatic: the processing is immediate, and cannot be prevented or interrupted.