Two-dimensional manual tracking of periodic movements: event and time interval analyses

Human visuo-motor functions were analysed by means of two-dimensional manual tracking tasks. A computer-based system for visual target generation, its movement control and real-time evaluation of the subjects' performance was developed. Various types of two-dimensional periodic target movements (over circular and square trajectories with different velocities) and various settings of tracking spot-joystick relation (normal and reversed direction) were used. Tracking success was expressed in terms of: (a) incidence of tracking errors; and (b) time spent within target. Results from the experiments performed with healthy non-trained subjects have demonstrated that tracking success is lower for a square target trajectory than for the circular one, and for higher target velocity than for the lower one. Reversed two-dimensional tracking was found to be very difficult. The results based upon the two criteria of tracking success (a,b) were different for the majority of tracking variants adopted. Quantitative and qualitative differences among subjects in tracking success were found. Two-dimensional target movements were substantially more difficult than one-dimensional ones with comparable parameters (analyzed in a previous paper).