Galton Bar (Performance)

The method of adjustment or method of average errors, asks the subject to control the level of the stimulus, instructs them to alter it until it is just barely detectable. The subject is instructed to adjust a stimulus until it appears equal to a given standard. The instrument used to establish this phenomenon is a long white board with a red line exactly at the center and two movable channels along the board. By moving this channel forward or backward the distance between the center point n and the channel can be varied. The experimenter sets the distance at a specific distance on one side of the board and ask the subject to adjust the other side exactly to the distance set by the experimenter. A meter scale is provided to measure the judgment.