The Forget-It-All Pill

A pill will be on the market in the not-so-distant future that will target certain memories and erase them, while not damaging other memories. But is this a good idea?

He's in a firehouse with some exhausted firefighters. His name is Jeffrey Mitchell, a psychologist and former firefighter. His job? To help emergency workers deal with the emotional impact of their work. The firefighters now are in a room sitting in a circle. They're not too talkative.

Then John tells his story. His squad had been called to the scene of a terrible traffic accident. One of the vehicles was a family sedan, but it was so badly mangled that you couldn't even tell what model it had been. It was obvious almost immediately that the parents, sitting in the two front seats and covered with blood, were dead.

There were two children in the back, and one of those was obviously beyond help as well. But the other child, a little girl of about 7, was sitting in the only corner of the car that was still relatively intact. Though not moving, she had no apparent injuries, and the firefighters sprang to work with high hopes. They were going to have to cut her out of the car, and so as...