The threshold of angular acceleration perception

The threshold for perception of angular acceleration is by no means a wellestablished quantity, although many investigators have attempted its determination by various methods. Mach (1875) described a method by which he determined the threshold for the sensation of rotation with a torsion swing. He found a threshold value of 2°/sec.2, as did Mulder (1908) and van Wulfften Palthe (1922). Tonnies (1932) and Woletz (1932), using an electrically driven rotating chair, also found 20/sec.2; Arslan (1934), however, arrived at only 0-5-10/sec.2 Buys (1940) found that a minimum acceleration of 1°/sec.2 was required to cause nystagmus in men. Buys & Rijlant (1939) found, for a large number of test-animals, that an average of 0-80/sec.2 was required to cause nystagmus of the head. Mowrer (1935) reported that 0 43-1*56°/sec.2 was required to cause nystagmus of the head in the pigeon. Ter Braak (1936), observing the minimum ocular deviations of rabbits photographically, found the much lower threshold of 0 10/sec.2 Mulder (1908) was the first to point out that the product of the time and the acceleration required to reach the threshold of rotational sensation is constant. Thus, for reaching the threshold, the required acceleration is the greater, the shorter the time of its action.