Behavior is almost always a mass noun and it is very rarely used in the plural. Incorrect:  You must reflect on your behaviors if you want to avoid repeating your mistakes. Correct:     You must reflect on your behavior if you want to avoid repeating your mistakes. Behavior is used in the plural in the fields of psychology, social science, and education. Five behaviors could extend life expectancy at 50 by more than a decade, even without the discovery of a single new drug or […]