11.1 Introduction

One soggy day in January, 15 students stood on the edge of a bridge that spans Highway 101 in Palo Alto, California. Each student held a poster painted with a bold orange letter. Lined up in order, the letters spelled a simple but provocative message for the Silicon Valley drivers below: "W-H-Y N-O-T C-A-R-P-O-O-L-?" The automobiles were moving at a snail's pace, bumper to bumper. However, one lane was nearly empty: the carpool lane.

As I read about this event in the San Jose Mercury News, I admired those students. Not only did they take action to improve the environment and quality of life in Silicon Valley, they also found a potentially powerful way to reach and influence people. It's hard to imagine a driver trapped in the rush hour crawl who didn't at least for a moment reconsider his or her commute strategy "Yeah, why not carpool? I could be home by now."

When I finished reading the article, I gazed at the picture and sensed something familiar, something symbolic. After a while, I recognized that this event matched my view on what many interactive technologies will do in the future. I identified five resonant elements from what the students did that January day:

1. They targeted a specific problem.

2. They attempted to persuade to change attitudes and behaviors.

3. They advocated prosocial behavior.

4. They acted at an opportune time and place.

5. They intervened on a collective level, not...