In 1942, a mother-daughter duo named Katharine Cook Briggs and Isabel Briggs Myers developed a questionnaire that classified people's personalities into 16 types. Called the Myers-Briggs Type Indicator, or MBTI, it would go on to become one of the world's most widely-used personality tests. But do these tests actually reveal truths about persona...

Are you an introvert ... or an extrovert? You might not know yourself as well as you think. Adam Grant talks with "Quiet" author Susan Cain and visits a workplace where personality training starts even before job training, to help you discover what your traits really are -- and how you can stretch beyond them. This episode is brought to you by W...