Precise effects of control position, indicator type, and scale side on human performance

Using a real hardware setup, the precise effect of control knob position, indicator type and scale side on strength of stereotype, index of reversibility (IR) and response time for a horizontal display/rotary control arrangement was studied. The main effects of the three main factors and the control position×scale side interaction were found to be highly significant for human response time, while the direction of instruction influenced stereotype strength. With analysis performed separately for top and bottom controls, for which different conditions of compatibility between clockwise-for-right, counterclockwise-for-left and the Warrick's principle exist, two different relationships were established between response time and stereotype strength. A further precise analysis of counterclockwise-for-left and clockwise-for-right stereotype showed that response time decreases not only with the clockwise-for-right stereotype strength, but also with the counterclockwise-for-left stereotype strength at bottom positions on which the counterclockwise-for-left stereotype agrees with the Warrick's principle. Finally, based on a consideration of response time, stereotype strength and stereotype reversibility, some practical implications for the design of horizontal linear display and rotary control configurations were given. The results of this study provide recommendations for interface design for control consoles commonly used in many different manufacturing systems.