Hilde Groth

Effects of Display Magnification, Proprioceptive Cues, Control Dynamics and Trajectory Characteristics on Compensatory Tracking Performance

An experiment was performed on the NOTS-UCLA heavy inertia tracking simulator to assess effects of display magnification, proprioceptive cues, displacement aiding, trajectory characteristics and trajectory direction on tracking performance. Particular attention was paid to interactions among these variables. The results showed that: (1) 5x magnification significantly decreased tracking error compared to tracking without magnification; (2) proprioceptive cues related to both azimuth and elevation significantly improved performance; (3) velocity plus displacement-aiding control dynamics (time constant = 0.1 sec) produced significantly lower error scores than unaided velocity control dynamics (time constant = 0.0 sec); (4) since no crossover tendencies were found, the effects of the varables appear to be independent.

Skill Acquisition in Multi-Dimensional Manipulator Control

Movements of a three-jointed electrically-powered manipulator were controlled by vertical movements of the second, third and fourth fingers of the subjects hand. Both two-dimensional and three-dimensional movement problems were examined. In the two-dimensional case, subjects were shown a silhouette of the manipulator with a lit endpoint or the manipulator endpoint alone. The manipulator was always fully visible in the three-dimensional case. Recordings were made of time-to-target, maximum deviation from a straight line path, and the percent of time that various numbers of controls were activated simultaneously. The results indicated that with practice the subjects tended to approach targets on a straight line course in both situations. They also increased the percentage of time that several controls were activated together. Being able to see the manipulator improved control coordination and decreased movement time in the two-dimensional case, but did not affect movement accuracy.

Measurement methodology for perceptual-motor performance under highly transient extreme heat stress

The existing state of the art for handling human performance under transient heat stress has been reviewed. It was concluded that it is necessary to develop a new methodology based on “micro-performance” measurements to assess severe localized transient heat stresses relevant to contemporary flight problems. The test procedure proposed is based on the rationale that a primary task, with difficulty that can be varied according to subject error in order to maintain a relatively constant subject performance level, can be used as a measure of the moment-to-moment perceptual load. In addition to the primary task, secondary tasks are suggested to help simulate problems in decision-making and verbal communication.