Technical improvements to the projection tachistoscope

Three disadvantages of the usual projection tachistoscope are discussed. Because of low mechanical precision, stimulus alignment is difficult. Because of rather low focal distances of the projection lenses, the stimuli provide visual angles that are often larger than desired, and the photographic shutters are noisy, are relatively inert, and have a limited service life. A new construction is described that avoids these disadvantages with a modified configuration of commercial elements: stable and precise mounting of the single channels, a double-lens projection system, and a noiseless, fast mechanical shutter based on a limited-rotation motor.