Robert C. Kennedy

Research in visually induced motion sickness

While humans have experienced motion sickness symptoms in response to inertial motion from early history through the present day, motion sickness symptoms also occur from exposure to some types of visual displays. Even in the absence of physical motion, symptoms may result from visually perceived motion, which are often classified as effects of visually induced motion sickness (VIMS). This paper provides a brief discussion of general motion sickness and then reviews findings from three lines of recent VIMS investigations that we have conducted.

Visually-Induced Motion Sickness: Effects of Adaptation

This research was designed to empirically examine the effect of adaptation training using a simulated rotary stimulation (SRS) technique on simulation sickness and inducing graded motion sickness through the systematic distortion of the relevant characteristics of two VR devices (VE and optokinetic OKN drum). Forty participants were randomly assigned to either a control (no training with SRS) or experimental (4-day training with SRS) condition. The results indicated that the experimental group who had prior training with SRS reported lower DLQ scores (Mean=2.09) than the control group participants (Mean=4.09) following VE exposure. Similarly, the experimental group who had prior training with SRS reported lower DLQ scores (Mean=1.95) than the control group participants (Mean=3.68) following OKN exposure. With regard to SSQ scores, the experimental group who had prior training with SRS reported significantly lower SSQ scores following the day 5 SRS exposure (Mean= 11.49) than the control group (Mean=1.60). Furthermore, the experimental group who had prior training with SRS reported significantly lower SSQ scores (Mean=11.75) than the control group participants (Mean=22.71) following VE exposure.

Training Effects in a Sickness-Inducing Environment

The present study was conducted to empirically examine the effect of adaptation training and transfer of training on simulation sickness by inducing graded motion sickness through the systematic distortion of the relevant characteristics of three VR devices (VE, OKN, and Real-World Entertainment Ride). It was hypothesized that for people who are highly susceptible to motion-induced sickness, the perceptual adaptation training method would transfer from a controlled laboratory environment to a real-world situation. Ten participants from a previous laboratory study were tested on a real-world virtual reality entertainment device. The results showed that subjects who had experienced adaptation training on the optokinetic OKN device had lower dizziness scores on the real world game. However, subjects who had experienced adaptation training on the VE device (HMD) did not have lower dizziness scores. This pattern of results suggests that crossover training from controlled laboratory environments to real-world environments is likely to be one-directional and platform specific. Our present findings imply a technique for mitigating sickness through pre-adaptation training in sensory re-arrangement that is feasible and has major practical implications in business, industry, the military and the private sector, where motion sickness symptoms limit previous exposure.

Transfer of Adaptation in Virtual Environments

The goal of this research was to investigate the reflexivity of the crossover effect−i.e. does adaptation on VE and OKN devices occur, and, if so, does transfer of this training occur in both directions (VE to OKN as well as OKN to VE). Forty participants were randomly assigned to either an OKN or a VE training condition. In the OKN condition, participants trained on the OKN device for four days, and were then tested on the VE and OKN devices on day five. In the VE condition however, they trained on the VE device for four days and were then tested on the VE and OKN devices on day five. The results indicated a 14.6% drop in DLQ scores and a 48.12% drop in SSQ scores for the OKN group. Similarly, a 21.28% drop in DLQ scores and a 23.64% drop in SSQ scores was obtained for the VE group. These results suggest that transfer of training occurred for both VE and OKN environments. Finally, these patterns of results are consistent and point to the importance of specific pre-adaptation training environments that would promote transfer to other motion sickness platforms. These findings have implications for training on different platforms.

Visually-Induced Motion Sickness: An Experimental Investigation

This study examined the effect of adaptation training on simulation sickness by inducing graded motion sickness through the systematic distortion of the relevant characteristics of a VR device. Forty adults between the ages of 18 and 47 participated in this experiment. In the control condition, the participants were required to complete a single self-propelled rotation simulation (SRS) trial, and then use a visually coupled head mounted virtual reality (VR) device plus exposure to an optokinetic rotating drum (OKN) device. In the experimental condition, all the participants took part in a five-session study in which they were exposed to five trials of the SRS and to the VE and OKN rotating drum. Immediately following each task, all participants were required to rate their level of dizziness. The results showed a significant main effect of adaptation training on both the VR and OKN rotating drum as reported by the dizziness ratings. These findings indicate that the difference in dizziness rates was markedly higher among the control group than the experimental group.

Criteria of Performance Tests for Fitness-for-Duty Assessment

Fitness for duty (FFD) tests can be used in workplace settings to identify performance impairment due to alcohol/drugs, fatigue, illness, etc. Accordingly, FFD tests must be both sensitive (able to detect impaired individuals), and more importantly, specific (very few false positives). However, high specificity for performance tests can be achieved only at the price of low sensitivity. A formula for the “sensitiveness” of FFD tests (the proportion of impaired persons detected by the test) is provided to permit comparison of performance and chemical tests based on the tests “sensitivity” and the rate at which persons are tested. An illustrative study is also provided to show that performance tests can meet the requirements of FFD testing. Results of four performance tests, which showed unequivocal deterioration when repeatedly administered to participants over a 24-hour testing period, are provided to demonstrate calculations of the sensitivity and specificity of the tests to fatigue effects.

Computerized Workplace Fitness Assessment: Sensitivity vs Specificity

Computerized fitness tests are used in workplace settings to measure for impairment resulting from factors such as environmental fatigue, toxic chemicals, environmental stresses, sleep disorders, high workload, illness, emotional upset, and others. One obstacle in implementing these instruments has been resistance from organizations due to concerns with accuracy of the tests and how the scores apply to the tasks in the workplace. Organizations are also often reluctant to adopt this type of instrument due to the potential for false positives in impaired performance. in order to develop a scoring method which addresses these issues by achieving substantial Specificity (>97%), while maintaining high Sensitivity, we employed computerized fitness tests to evaluate subjects with graded alcohol doses. By implementing Multiple Regression and Multiple Cutoff Analyses, we were able to achieve the desired levels of Specificity, while maintaining high Sensitivity.