They sniff, wag their tails, fetch, and run in packs. Inside their plastic and metallic skins, robotic dogs programmed by engineering students at Yale University even have a social conscience.

The mechanical canines, equipped with just about everything but a wet nose, are wired to sniff out toxic materials at former landfills and radioactive sites, providing environmental information about parks, school yards, and other public spaces.

The robots have spurred toxic search projects in the United States, Europe, and Australia. They are the brainchild of Natalie Jeremijenko, a lecturer in engineering at Yale and self-described technoartist.

"Technology is a social actor," she said. "These dogs are programmed into instruments for social activism. It's technological politics in another form."

The dogs were originally designed, manufactured, and marketed commercially as toys by Sony Electronics Inc., Mattel Inc., and other companies.

Sony's AIBO, which has been on the market since 1999 and sells for $1,599, is intended to draw emotional responses from its masters, said Jon Piazza, a spokesman for Sony robotics entertainment in New York. The dogs' software platform is available on the company's web site and may be used for other purposes, he said.

For example, a competition has drawn 20 universities with programmed robotic toys that participate in a "Robo Cup," he said.

The Yale project is different.

Jeremijenko, a mechanical engineer and computer scientist, designed her robotic dogs 18 months ago as a spinoff from a research project she began in the late 1990s that she calls an Interaction Triggered System. Its intent was to see how people interact with technology.

Distribution and cost are two major advantages of transforming the dogs into community activists. The toys are easily available, and gutting them for a university engineering project is the least expensive way to teach robotics, she said.

And dogs--the real ones--are a good model for robots, because they're companion animals and "can sense things we can't sense," Jeremijenko said.

Robotic technology is hardly new. It's increasingly being applied to repetitive factory tasks or dangerous work such as defusing bombs or finding victims in collapsed buildings.

Advances in microtechnology lead to ever-smaller sensors as engineers and scientists seek new uses. For Jeremijenko, one of these new uses is the feral dog project--so named, she says, because feral dogs are street-smart and wily.

The dogs' "brains" are upgraded and their "noses" programmed to pick up the scent of common volatile organic compounds--such as paint thinners or dry cleaning fluids--or more dangerous toxins. They also are built to navigate a variety of terrains.

In addition, cameras are placed in the dogs' hindquarters to allow researchers to observe their interaction with handlers.