Japanese electronics companies have begun marketing intriguing new products incorporating "fuzzy logic," a concept that was invented in the United States but has not caught on with American manufacturers.

Fuzzy logic allows computers to handle ambiguous information - such as big and small or hot and cold - to control "smart" consumer and industrial products.Last month, for example, Sony Corp. announced a hand-held computer incorporating fuzzy logic, the PalmTop PCT-500, that recognizes words written with a special pen on its screen.

A washing machine made by Hitachi Ltd. determines how much soap to use and the temperature of the water. Matsushita's Housing Products Co. is marketing a shower system with a more accurate water temperature control, and the Yamaichi brokerage firm is using a computerized trading system based on fuzzy logic.

"The Japanese are going to bury us in a couple of applications," said Tom Schwartz, a Mountain View, Calif.-based consultant. "Then we are going to say, 'Uh-oh, we are going to have to play catch-up again.' "

Lotfi Zadeh, a professor at the University of California in Berkeley who developed the theory of fuzzy logic 25 years ago, said U.S. companies have yet to embrace the theory or to develop products around it, primarily because of the stigma scientists associate with imprecise theory.

"Our culture is based on classic truth, Aristotelian logic and black and white," said Mr. Zadeh, a computer science professor. He said fuzzy logic is controversial in the United States because of its departure from traditional logic.

"To a lesser degree, it's because fuzzy is not a respectable word," he said. "People respect precise reasoning. Fuzzy logic deals with imprecise reasoning.

"Essentially, the Japanese are making products which have a high IQ," he said, as opposed to traditional computer systems that are limited to reading on/off or yes/no signals.

Last month, Chatsworth, Calif.-based Fisher, a unit of Sanyo Electric Co., unveiled an 8mm video camcorder based on fuzzy logic circuitry. Sanyo, which will begin marketing the camcorder in the United States in June, plans to use the term "fuzzy logic" in its promotion of the product.

"There were a few eyes crossed at first, because the technology is connected with focusing," said David Claus, a spokesman for Sanyo/Fisher. ''But once the public becomes aware, fuzzy logic is actually quite a descriptive term."

The fuzzy logic in the new camcorder allows it to evaluate lighting conditions and focus more quickly than other models, the company says.

The Japanese government has already invested about $120 million and backed two research organizations dedicated to developing products based on fuzzy logic. One effort, the Laboratory for International Fuzzy Engineering in Tokyo, has 48 companies participating.

In March, Japan's Ministry of International Trade and Industry set up the Fuzzy Logic Systems Institute in Fukuoka City, a research center to develop a fuzzy logic system for use in computers.

Mr. Zadeh said Japanese companies currently have 2,000 patents for products using fuzzy logic. The logic can be incorporated into artificial intelligence systems, software and computer memory chips.

"Fuzzy logic systems use linguistic variables, such as small, large, fast, slow," said Mr. Zadeh. "They use words instead of all numbers."

Togai Infralogic, a private company in Irvine, Calif., is one of the few U.S. companies making a fuzzy logic product, a computer chip, but it is sold only in Japan.