Control/Response Compatibility, Muscle Synergy and the Virtual Visual Field: What you See is What you Get

Abstract

Three components were hypothesized which could affect operator response in the manual control of a system. These included muscle synergy compatibility (MS), geographic control/display compatibility (CD), and visual-field compatibility (VF). Disruption in one of these was suspected as a contributing factor in documented accident cases. A 2χ2χ2 between-subjects factorial design was used to evaluate all combinations of compatible and incompatible arrangements based upon these variables, using 64 undergraduate students as participants. A static-target acquisition task was used in which subjects manipulated a specially designed joystick to move a cursor to defined target locations. Performance measures included reaction time, movement time, homing time, and frequency and magnitude of directional reversals. Results indicated that visual field (VF) compatibility/incompatibility significantly influenced reaction time, homing time, and reversal frequency and magnitude, while CD and MS manipulations had no significant main effects on performance. Significant gender effects were also found. The results of this study suggest that compatibility of control input and system response is judged primarily by direction of movement in the virtual visual field (self reference). This has implications for the design of systems such as small mobile cranes where the operator may be repositioned relative to a fixed directional control.