(FORTUNE Magazine) – Once again, Japanese companies are taking a technology invented in the U.S. and using it to create groundbreaking consumer products. The new technology is called fuzzy logic because it enables machines to think more like humans $ -- i.e., in a ''fuzzy'' way, making fast judgment calls based on whatever information is available. When equipped with electronic controllers with such thinking built in, everyday household appliances like vacuum cleaners and washing machines perform better, their proponents say, and often use less electricity. Lotfi Zadeh, 69, an electrical engineering professor at the University of California at Berkeley, developed the theory behind fuzzy logic in 1965. While U.S. companies have shown sparse interest in pursuing it, Japanese giants such as Hitachi, Mitsubishi, and Matsushita jumped in. ''They are reaping the fruits of the efforts they started ten years ago,'' Zadeh says. Alas, he never established legal ownership of his idea. ''If I had, perhaps I'd be a rich man today.'' Matsushita recently introduced a vacuum cleaner that uses fuzzy logic to pick up carpet fuzz. A built-in sensor gauges the condition of the floor, and then a microchip determines how much power is needed to suck up the dust. Matsushita is also selling a fuzzy washing machine. It adjusts its spin cycles according to the size of the load and type of detergent used. Its name: Aisaigo Day Fuzzy (aisaigo translates as ''my beloved wife''). Hitachi makes a competing fuzzy washing machine and also a dryer, while Mitsubishi has introduced a fuzzy air conditioner that uses 20% less electricity than most conventional models. The extra efficiency doesn't come cheap -- Matsushita's washing machine costs $523, and the fuzzy vacuum cleaners go for as much as $365. Both products are sold only in Japan, and Matsushita has no plans yet to export them. But Mitsubishi will soon bring its fuzzy air conditioners ($1,637 apiece in Japan) to the U.S. Zadeh predicts that U.S. consumers will snap up fuzzy logic products. ''American companies are calling me now to find out about it,'' he says. ''But it will be difficult for them to catch up. American industry is just not geared for this sort of product development.'' (For more on the competition between the U.S. and Japan to produce high-quality goods, see Manufacturing.) - M.A.