The apparatus consists of a Random Number Generator (RNG) connected to a minicomputer. The RNG produces pulses randomly on two channels. The pulse rate can be set by the computer. The behaviour of the Random Number Generator is fed back to a display in the form of a line which starts on the top of the screen and develops downwards in time with the horizontal coordinate being determined by the cumulative difference in bits of both channels.
(for a demo of the display click on the figure)
The display is updated after each interval. Number of intervals and duration thereof are experimental parameters.
The goal of a subject is to influence the behaviour of the RNG in such a way that the line on the display develops into the target direction. Each of the 14 subjects participates in a total of 28 experimental runs. Fourteen of those have a targetdirection 'left' and 14 have a targetdirection 'right'. During the last 8 runs the RNG is switched off and pulses are used that have been recorded earlier but were not observed until they were used in these so-called prerecorded runs.
Run-durations vary depending on clock rate, number of intervals and interval duration, between 3 and 12 seconds. The subject initiates a run by pressing a button. For a detailed description of the design and the experimental parameters click here.