The world's first mass-marketed robot, Sony's Aibo, recognizes its owners' faces and is programmed for sympathy, like a canine companion. Its eyes light up in red to show anger, green to convey happiness. It even learns its own name.

Aibo owners tend to be fiercely loyal, too. The robots have even been hacked by tinkerers seeking to add their own modifications. But none of that prevented Sony Corp. from announcing last week that it was scrapping the four-legged robot pet as part of the company's bid to reverse flagging fortunes and cut costs.

Like so many things Sony has made over the years, the Aibo is a niche product. And since Sony is pulling the plug on robot production as part of a major restructuring, so goes the Aibo.

That isn't just disappointing Aibo fans, who bought 150,000 of the toy poodle-sized machines since they were first introduced in 1999 and now worry they won't be able to get spare parts.

It may also have robbed Sony of some of mystique.

Typical of now-dispirited Aibo owners, Paul Wallingford isn't placated by Sony's promise to provide maintenance for Aibos for seven years after production ends in March.

"I think you do develop an attachment to them," Wallingford, the owner of a Los Angeles-based Internet business, said by telephone.

He owns four Aibos and lately has been keeping them turned off often so they're less likely to develop problems.

The Aibo, which costs about $2,000, delivers an amusing illusion of spontaneity and personality. It comes in black, white, brown and gray and is programmed to move about on its own.

It has image-recognition capabilities and a digital camera in its head that allows it to chase a special pink ball and avoid bumping into walls.

To many, the Aibo represented the tradition of innovation at Sony, which gave the world the Walkman portable music player and PlayStation video game machine.

It matters little to Aibo fans that Tokyo-based Sony — with its sprawling entertainment business including movies, music and video games — has opted to reorganize and focus on its core electronics business in order to better compete with the likes of Samsung Electronics Co. of South Korea.

Owners have created fan clubs around the world, and some even dress up their canine robots like babies.

Some hospitals used the Aibo — which means "pal" in Japanese and combines the first two letters of "artificial intelligence" combined with "bo" from robot — in therapy.

The robots' charm comes in part from how their behavior somewhat reflects how they've been treated by their masters. At times, an Aibo will refuse to be toilet-trained and impudently raise a hind leg — although, of course, it won't ever wet the rug.

An Aibo can understand 100 words and phrases and recognize three people's faces as it stores digital photos in its brain. It knows when its behavior is being praised because it has a sensor on its head that recognizes when it's being petted.

Later versions have a built-in camera so Aibos can serve as home sentinels, and e-mail their owners if something appears to be amiss.

Takeshi Ohashi, a Kyushu Institute of Technology professor, considers Aibo a gem of technological finesse. He plans to appeal to Sony to bring the robots back.

Ohashi has his motives. He is an organizer of RoboCup, an annual international competition in which teams use Aibos and other robots to play soccer.

Masato Maruyama, an engineer, believes Sony isn't just hurting Aibo owners, who feel as if they're being told their pets have just seven more years to live.

"I feel the decision to withdraw from a product that's so representative of Sony heralds an end for Sony as a global leader," he said.

Richard Walkus, a Madison, N.J., man who has a Web site devoted to Aibo, concurs.

"They lost something," he said of Sony. "They lost stature."