Abstract: A person's memory of sequences is tested by shifting a relationship between switches and colored lights which they control. Switches in a row light colored lamps in a fixed sequence. A two part circular switch with opposed contacts equal in number to the switches or colors may be turned to shift the sequence of colors which the switches control. One part of the circular switch may be inverted so that the sequence of colors controlled by the switches may be reversed and may be shifted in reversed order. Inserts positioned between the two parts of the circular switch change the sequential relationships of colored lights and switches.