1994: Most interaction between people is either in person or by telephone. Because people relate to each other through direct communication, most of the accepted rules of courtesy still govern interaction.

Today: With tens of millions of people using e-mail to do everything from keeping in touch with family members to selling their cars, the rules of social interaction are changing. The faceless nature of e-mail, coupled with the fact that communication does not take place in “real time,” often makes people less inclined to adhere to traditional rules of courtesy and conduct.

1994: During the 1990s, awareness of psychological depression and its treatment make significant progress. In 1994, particular emphasis is given to research into the genetic causes of manic depression, or bipolar disorder. As a result of research and public education, depression carries less of a stigma than it did in the past, and people...