Sojin Park

We brush our teeth consistently for our entire lives, yet we never become masters of tooth brushing. Even after 10 years, there are still spots on our teeth that aren’t properly cleaned, so we end up going to the dentist. We even get told, “This area isn’t being brushed well.”

What’s the reason for this? According to Changjun Kim, there are two reasons.

First, there’s a lack of motivation to brush well. Unless someone’s teeth are particularly bad, hardly anyone thinks, “I need to become a master of brushing my teeth.” Once we start brushing independently around age 7, it becomes difficult to have the motivation to brush better.

Second, we don’t receive timely and accurate feedback. We don’t get feedback in a timely manner on how we brushed, what areas were done well, and what areas were lacking. After brushing the same way for a year, only after going to the dentist and being scolded do we finally receive feedback on whether our brushing was good or not. Even though receiving timely feedback right after an action is important for becoming a master of something. (For example, at the dentist, tools like a dental mirror, water pick, and floss can be used to assess the accuracy of brushing.)

Considering these points, it’s difficult to become a master simply by repeating something for 10,000 hours. The conditions of “deliberate practice” need to be met—having strong motivation to improve one’s skill, and receiving specific feedback at the appropriate time.