Robert S. Kennedy

Dropouts and Aftereffects: Examining General Accessibility to Virtual Environment Technology

Are current virtual environments (VEs) usable by the broad spectrum of people who may wish to utilize this technology? The current study, which examined over 1000 participants, indicates the answer to this question is a definitive ‘no’. Virtual environment exposure was found to cause people to vomit (1.1%), experience nausea (71%), disorientation (70%), and oculomotor disturbances (79%). Overall, 88% of participants reported some level of adverse symptomatology, ranging from a minor headache to vomiting and intense vertigo. These disturbances led 12% of those exposed to prematurely cease their interaction. Dropout rates as high as nearly 50% were found in exposures of 1 hr in length. In addition, long-term aftereffects were found, including headaches, drowsiness, nausea, and fatigue. These problems could substantially reduce the accessibility of VE technology by the general public and thus must be resolved if this technology is to be widely adopted.

Signal Word and Color Specifications for Product Warnings: An Isoperformance Application:

Recent work in the area of color and warnings has indicated that the level of hazard communicated by signal words varies as a function of the color in which they are printed. These findings suggest that signal word and color combinations create a continuum of perceived hazard. Although individual experiments advance the understanding of how color affects the perception of product hazard, explicit data do not always provide label designers and product manufacturers with the tools necessary to successfully apply them. To explore how color and signal words can be jointly used, the present effort applied the isoperformance technique to the problem of specifying signal word and color combinations. This technique identifies combinations of variables that produce equal (iso) levels of warning (performance). Using perceived hazard data from 30 participants, signal words and colors were systematically grouped into categories that conveyed equal levels of hazard. How the isoperformance technique might serve as a tool for label designers is described.

Overcoming Unreliability in Operational Measures: The Use of Surrogate Measure Systems

Improved assessment of operational performance is critical for studies of selection, training and human engineering as well as those examining the performance effects of environmental changes, chemicals or other stressors imposed by military duties. The present discussion focuses on what we consider to be the major problem with such enterprises – the lack of sensitivity of operational measures because of poor reliability. The well-documented impact of low field measure reliability includes the inability to demonstrate differences resulting from experimental treatments and the chronic underrepresentation of validity in predictive studies. This paper describes a general methodology for using specially-developed performance batteries as surrogates for real-world performances, in particular for determining whether such performance may be disrupted by environmental or chemical agents. The logical and metric rationale of surrogate measurement is presented, and the advantages and disadvantages are discussed and compared to alternative approaches (job samples, synthetic tasks, etc.).

Developing Automated Methods to Quantify the Visual Stimulus for Cybersickness

Simulator sickness is a significant human factors issue in simulator and virtual environment systems. The extent to which users are adversely affected by sickness-inducing stimuli in virtual environments may hinder the behavioral goals sought (training, systems evaluation, etc.). To alleviate the problem, it is first necessary to accurately and reliably quantify the amount and type of visual motion stimulation that leads to motion sickness-like discomfort. This paper describes a human performance-based approach to the development of a system capable of measuring the visual stimulus for motion sickness. Military flight simulator trainees reported severity levels of sickness. A video camera was used to capture a significant portion of the simulated out-the-window visual stimuli to which they were exposed and a PC-mounted, frame-grabber algorithm was used to score the kinematic characteristics of that stimulation. Results show a significant positive correlation between roll motion and overall sickness. Development of these and other methods to quantify the visual stimulus for cybersickness are discussed.

Effects of Secondary Loading Task Modality on Attentional Reserve Capacity

The purpose of the present study was to use a newly-developed measure of reserve attentional capacity to evaluate unitary versus multiple resource theories of attention. Participants performed a primary visual monitoring task and were presented with visual, auditory, and tactile secondary loading tasks. The data indicate that participants maintained performance on the primary task, as instructed, and performed the secondary task with any remaining attentional reserve capacity. A significant difference was found on the basis of secondary task modality, wherein performance on the visual secondary task was significantly worse than that of secondary auditory and tactile tasks. This result was additionally supported by scores on a subjective workload questionnaire. Although the data do not preclude interpretation in terms of a unitary resource model, data trends offer potential support for a multiple resource model.

Methods for Correlating Visual Scene Elements with Simulator Sickness Incidence

Simulator sickness occurs in a large number of Army, Navy, and Marine Corps simulators, and is most prevalent in moving-base, rotary-wing devices which employ cathode ray tube (CRT) video displays as opposed to fixed-wing, dome-display trainers with no motion base. Based on data from a factor analysis of over 1000 Navy and Marine Corps pilot simulation exposures, a new scoring procedure was applied to two helicopter simulators with similar rates of simulator sickness incidence. Based on the factor analytic scoring key, the two simulators showed slightly different sickness profiles. Preliminary work was begun to record the visual scene by video frame-by-frame decomposition and automated scoring algorithms were developed. The findings are discussed from the standpoints of (1) recommendations for future design and use of simulators, and (2) the metric advantages and other merits of the “field experiment” methodology to address human factors problems with simulator sickness.

Virtual Environment Exposure Drop-Out Thresholds

The use of a virtual environments (VE) for training purposes has the potential to create motion sickness-like symptoms in participants; in some, these symptoms are so severe that the user drops out of the VE training. The purpose of this study is to characterize the frequency of VE dropouts as well as the thresholds and associated symptoms experienced by those who cannot complete their VE exposure. When 245 students interacted with a VE for varying amounts of time performing a variety of tasks, 19% consistently could not complete their assigned VE exposure, even though all participants were exposed to the same virtual world and completed the same tasks. Dropouts experienced symptoms such as nausea, oculomotor disturbances, and disorientation. Insights into the potential differences between dropouts and finishers emerge via an examination of their interaction with the virtual world and suggest that controlling, streamlining, and limiting VE interaction may reduce the number of dropouts.

Motion Sickness Symptoms and Perception of Self Motion from Exposure to Different Wallpaper Patterns

Vection refers to the compelling visual illusion of self-motion experienced in virtual environments by stationary individuals when viewing moving visual surrounds. Early research with these perceptions generally employed a vertically striped drum of about 1.5 meters in diameter. The illusion of self-motion or vection generated in these optokinetic drums is particularly useful for studying the effects of optic flow imagery in virtual environments because the subject determines the precise time at which the vection occurs and the nauseogenic experience is stopped; thus problems of motion sickness, nausea, and vomiting can be monitored and/or minimized. This vection, presumably related to the reflexive optokinetic nystagmus (OKN), experimentally presents a non-invasive neural visual response which may be safely used for the investigation of possible motion sickness symptoms ranging from the so called Sopite syndrome to the nausea and vomiting which may be experienced in some virtual environments. Further, to be able to examine the effects of color, texture, and differing scene content, we constructed a vection drum with easily reconfigurable displays. Therefore, for stimulus material, instead of the conventional black and white stripes, we employed differing patterns of household wallpaper. Results showed that, while equal amounts of vection were produced with the wallpaper, one pattern appeared to produce less sickness.

Postural Stability and its Relation to Simulator Sickness

The use of simulators as training devices has become widespread, especially in the military for pilot training. Although simulators provide an effective means of training pilots at a much reduced cost compared to actual flight, simulator sickness may result. Postural instability is one symptom of this sickness and a well-documented effect of simulator exposure. Postural stability is often measured before and after simulator exposure to determine decrements due to exposure. However, it does not appear that this measure is typically used as a predictor of sickness. The analysis reported in this poster attempts to determine if there is a relationship between postural stability and simulator sickness. Pre-exposure postural stability data and post-exposure simulator sickness data were collected from Navy pilots in conjunction with a training session in a helicopter simulator. These data were analyzed for relationships between postural stability and sickness. It was hypothesized that individuals who are less posturally stable will be more likely to experience simulator sickness or will experience more severe sickness. On the other hand, individuals who are more posturally stable will be less likely to experience simulator sickness or will experience less severe sickness. Several analytical techniques were attempted: Pearson correlation, Spearman correlation, Gammma and Lambda categorical methods, ANOVA, and Trend Analysis. Each technique evaluates a different aspect of the data and no one technique best represents the findings. Although clear, strong relationships have not been found, there is evidence suggesting that postural stability is associated with simulator sickness as hypothesized in this study. Further research with a more diverse population and different types of simulators, including virtual environments, is clearly warranted.

RELIABILITY GENERALIZATION: A VIABLE KEY FOR ESTABLISHING VALIDITY GENERALIZATION '

Even with radical restriction of range, reliability coefficients from 10 studies gave an average interstudy value of .74, suggesting constancy of reliability over diverse experiments. A value from a new test can help index reliability of tests not previously studied.