Cain went to a two-month summer camp when she was nine years old. Her family liked to spend time together reading independently, so she took several books to camp; however, she was the only one interested in quiet reading, so she put away her books and joined in with the rest of the group activities despite feeling uncomfortable. Cain also reflects on her jarring transition from elementary school to middle school. She found the shift and additional social pressures overwhelming, particularly in the cafeteria, where “the voices of hundreds of kids bounced off the massive cinderblock walls” (19). Cain compares her experience to that of Davis, an introverted Asian American sixth-grader in a white-majority school. On his first day of sixth grade, Davis was nervous in the loud, chaotic areas of the school, and he felt more comfortable in the quiet classrooms. On the bus ride home, someone put gum in Davis’s hair. Although most of Davis’s peers appeared to be happy, Cain argues that some were probably struggling, like Davis.

Introverts’ nervous systems, Cain writes, are more reactive to social and sensory experiences than are extroverts’ nervous systems. Thus, introverts usually prefer quieter spaces and fewer friends, while extroverts tend to “crave stimulation.