"Even if the [car] alarm attracts attention to a crime, will anyone interfere? Not likely, said Harold Takooshian, a professor of psychology at Fordham University who has run experiments near his office on Manhattan's West Side. He did not use car alarms, but he did study how bystanders react to car thieves.

In one study, a researcher pretended to be a thief nervously using a coat hanger to break into a car and steal from it. Most bystanders on the sidewalk who noticed the burglaries did nothing. In the minority of cases where people got involved, sometimes the bystanders called the police or questioned the thief, but twice as often their involvement consisted of helping the thief break in.

Most of these helpful souls apparently assumed, without asking, that it was the thief's own car. But a few apparently had larcenous ideas of their own. "Hey baby, this is my shtick" said one youth, who took the hanger from the thief, used it to open the door, watched the thief remove a television from the car, and then asked for a tip.

These findings, together with similar results from 29 other American cities where Dr. Takooshian repeated the study, do not seem to show great benefits from alerting a neighborhood to car theft."