Kafka presents an experimental method for studying one of the ego functions, the sense of time, under varying laboratory conditions. He shows a small light to subjects in a dark room and tells them that the light will be moved, first at random and then so as to form letters and sentences. A period of darkness precedes each period during which the light is moved. The subjects are not told that they will be asked to estimate the duration of the two light periods and the two dark periods. The subjects in general thought the dark periods longer, probably because of the diminution of stimuli. Some subjects underestimated and others overestimated the duration of the various periods.