1996-February-17 "Getting to Grips with the Perfect Chopsticks" CHOPSTICKS have been used in Asia for more than 2,000 years, yet researchers are only now investigating the subtle design factors that determine whether a hot steamed dumpling lands in your mouth or in your lap. After a detailed ergonomic study, however, Swei-Pi Wu of the Hua Fan College of Humanities and Technology in Taipei, Taiwan, believes he knows the vital statistics of the perfect chopstick. Wu studied handle diameter, tip diameter and tip angle -- the degree of taper from the handle to the tip. Each factor has a "significant influence" on eating efficiency, he concludes, in the latest issue of Applied Ergonomics. Wu tested the performance of experienced chopstick users in typical dining tasks -- pinching, pulling, shearing and thrusting -- using a dozen pair of chopsticks representing the full variety available in Taiwan. Handles ranged from 4 to 8 millimetres in diameter, tip angles from 0 to 6 degrees, and tip diameters from 8 millimetres down to less than 1 millimetre. He asked the subjects to pick up as many peanuts as they could for one minute, pull on a rubber eraser that was tethered to a strain gauge, cut open a sponge cake, and thrust 10 pieces of simulated food towards their mouths. None of the chopsticks excelled at all of the tasks. Those with the largest handle and tip diameters were best for pulling, but too awkward for the finer task of pinching. Chopsticks with a high tip angle worked well for shearing the sponge cake, but were likely to slip when picking up peanuts. Wu concludes that the most efficient chopsticks for general use would have handles of 6 millimetres diameter, tips of 4 millimetres diameter, and a 2 degree tip angle. In a previous study, Wu found that the length of a chopstick is also important, especially for pinching. Wu recommends that families stock chopsticks in two sizes: 240 millimetres for adults and 180 millimetres for children, while restaurants should provide a "one-size-fits-all" model measuring 210 millimetres. Wu's study is unlikely to be the last word on chopstick design, however. Erik Wegweiser, a Boston-based chopstick aficionado, believes that a stick's cross-sectional shape, rather than its diameter or tip angle, is the most important factor. "Japanese chopsticks are rounder, pointier, and shorter," he notes, "while the Chinese ones are longer and squarer." The round ones, says Wegweiser, "are obviously more difficult to deal with." -- Brad Hurley Taken from New Scientist, 1996-02-17 and Reproduced with permission. © Copyright 1996 RBI. For more science news and views, check out New Scientist Planet Science.