The concept may sound antithetical to a digital era defined by ubiquitous communication and interactivity, but Slydial turns out to be only the latest in a breed of new technologies that fit squarely into an emerging paradox: tools that let users avoid direct communication.

Technologies like e-mailing and blogging give the communicator the power to choose the time and manner of expression. Now, some academics, text messagers and creators of technologies say a trend has emerged: We are constantly just missing one another — on purpose.