Edward J. Rinalducci

Method of adjustments versus method of constant stimuli in the quantification of accuracy and precision of rendered depth in head-mounted displays

The utilization of head-mounted displays (HMDs) in high-end applications such as medical, engineering, and scientific visualization necessitates that the position of objects be rendered accurately and precisely. Accuracy and precision of rendered depth for near-field visualization were measured in a custom-designed bench prototype HMD. Experimental results were compared to theoretical predictions established from a computational model for rendering and presenting virtual images by Robinett and Rolland (1992). Such a theoretical model provided the necessary graphics transformations required so that rendered virtual objects be perceived at the rendered depth in binocular HMDs. Three object shapes of various sizes were investigated under two methodologies: the method of constant stimuli modified for random size presentation and the method of adjustments. Results showa2mm and an 8 mm performance for the accuracy and the precision of rendered depth in HMDs, respectively. Results of the assessment of rendered depth in HMDs for near-field visualization support employing the method of adjustments over the method of constant stimuli whether or not the method of constant stimuli is modified for random size presentation.

Characteristics of visual fidelity in the virtual environment

This paper provides an overview of the literature on the visual system, placing special emphasis on those visual characteristics regarded as necessary to produce adequate visual fidelity in virtual environments. These visual cues apply to the creation of various virtual environments including those involving flying, driving, sailing, or walking. A variety of cues are examined, in particular, motion, color, stereopsis, pictorial and secondary cues, physiological cues, texture, vertical development, luminance, field-of-view, and spatial resolution. Conclusions and recommendations for research are also presented.

Further Experiments on the Effects of Foveal Load on Peripheral Vision

The main objective of this research was to investigate the effects of foveal load on sensitivity in the peripheral visual field. The first experiment was presented at previous meeting of the Human Factors Society. Here, foveal load was manipulated by comparing the fixation of a cross vs. a simple first-order compensatory tracking task display. Peripheral sensitivity was determined simultaneously for light flashes presented at different eccentricities along the horizontal meridian. In general, the results showed no losses in peripheral sensitivity or a “tunnel vision” effect under the experimental conditions employed. Three more experiments have been carried out since that presentation. More complex tracking tasks have been employed in order to vary foveal load and the difficulty of the perimetry task has also been manipulated in one experiment by including lights on the vertical meridian. Whether or not a loss or a gain in peripheral sensitivity depends upon the complexity of the foveal task and to some extent the perimetry task. Results are discussed in terms of arousal and resource theory.

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.

The Effects of Text Messaging on Driver Distraction: A Bio-Behavioral Analysis

This study was designed to empirically examine the effects of text-messaging on driver distraction. Thirty participants were required to perform a driving simulation task while text-messaging using a cellular phone device. Driving errors as measured by lane deviations, crossing the median, crashes, etc., were recorded and analyzed as a function of the distracter. Physiological measures (EEG) were also recorded during the driving phases to quantitatively measure the participants level of cortical arousal. It was hypothesized that text-messaging would affect driving ability and the level of cortical arousal. The results indicated higher levels of arousal and a prevalence of the theta frequency (4–7 Hz), which is associated with distractibility as a result of text-messaging activity. In addition, participants showed an increased number of driving errors as a function of text-messaging distractibility. These results have major implications for in-vehicle systems design, traffic safety, and driver attention and workload.

Effect of Aging on Driving Performance

The current research investigated the effects of aging on driving performance. Perceptual measures included far and near point acuity, stereopsis, a measure of lateral and vertical phoria, color vision; and spatial contrast sensitivity. Cognitive functioning was examined using the Useful-Field-of-View (UFOV) Test. In addition, each driver completed a Driving Habits Questionnaire (DHQ). Although older drivers tended to have fewer collisions and exhibited better adherence to speed limits in a simulated driving task than did younger drivers, older drivers appear to be at a greater risk of having a collision, resulting from degraded divided and selective attention compared to the younger drivers.

EFFECTS OF RADIO TUNING ON DRIVING PERFORMANCE

This paper introduces some of the research work on the effects of telematics, in this case a radio system, on drivers performance. Twenty-four undergraduate students participated in a series of simulated driving scenarios. In the pre- and post-allocation phases, all participants were required to drive two-four minute phases to establish their baseline scores. In the allocation phase, they were required to tune to a series of local radio stations while performing the same driving scenarios. The results indicated that participants committed more driving errors and violations during the radio-tuning phase than any of the other pre- and post-allocation phases. These errors were manifested in an increased number of crossing the median marking, leaving the roadway, and/or lane deviation. The implications of these results are also outlined in the present paper.

The Effects of Transient Adaptation on Cockpit Operations

Two experiments examined visibility loss as a function of sudden changes in luminance level such as those that might be experienced by a pilot in a high- performance aircraft. Luminance levels chosen were similar to those found at dawn and dusk or under nighttime conditions. In the first experiment, the observer was required to recognize test letters varying in spectral composition similar to what might be seen on a HUD. The large background field changed upwards or downwards a 1– or 2–log unit increment. Results indicated losses for both directions of change. No differences were found between the different test-letter colors. In the second experiment, the observer was exposed to changing background fields (2–log unit upward and downward changes) which were presented from 0 to 5 degrees from foveal fixation. In general, results indicated greater effects for background stimuli closest to central fixation (in the region of target location) and decreasing to zero with increasing eccentricity.

The Effects of Transient Adaptation on VDT Operations

The purpose of this study was to investigate the effects of transient adaptation in a simulated VDT operation. Specifically, the study attempted to determine transient adaptational effects that may result in visibility losses or decrements in visual performance, when an observer shifts his or her point of regard from a region of higher overall luminance (e.g., a negative contrast source document with dark characters on a light background) to a region of lower overall luminance (e.g., a positive contrast video display with light characters on a dark background), and vice versa. The source document and VDT display were simulated using a back-projection, free-viewing apparatus. The luminance shifts made up the two transient conditions: a downward change in luminance level (i.e., negative to positive contrast displays), and an upward change in luminance level (i.e., positive to negative contrast displays). The results of these two transient state conditions were compared to two steady state conditions in which there was no change in luminance level or flash contrast thresholds (i.e., Sloan-Snellen test-letter flash was superimposed on the display) were determined using the up-and-down psychophysical method combined with the forced-choice technique and knowledge of results. The ratio of the transient state contrast threshold to the steady state contrast threshold served as an index of visibility loss. The goal of the research due to transient adaptation in VDT operations, but to also determine possible advantages and disadvantages of positive vs. negative contrast video displays.