Biomedical subjects

R M Wildzunas

Publications and source records attributed to R M Wildzunas.

3 recordsLinked to original sources

PubMed1996

Visual display delay effects on pilot performance.

BACKGROUND: The Helmet Integrated Display Sight System (HIDSS), originally proposed for the RAH-66 Comanche, displays sensor data from FLIR and image intensifiers, as well as flight instrument and targeting data. All these data will be processed through onboard computers before being displayed on miniature CRT's. In addition to processing delays, delays also are arising from the helmet tracker and from sensor slewing that may increase the total visual display delay to as much as 250 ms. METHODS: Because display lag is one of the most important limitations affecting the ability of an aviator to use a display, we investigated the effects of 0, 67, 133, 267, 400, and 533 ms visual display delays on the flight performance of 10 volunteer U.S. Army aviators in a full motion flight simulator. RESULTS: There were few performance decrements at 67, 133, or 267 ms delays as compared with the 0 ms delay condition. Significant performance decrements consistently were observed at 400 and 533 ms delays. CONCLUSIONS: Given the anticipated visual display delays for the proposed system, flight performance, as measured within the range of flight conditions and profiles examined, should not be affected significantly, although the aviators will experience an increase in workload to compensate for the delay effects. During low level flight, they will face additional risk due to their proximity to obstacles and a resulting decrease in their time to react and avoid collisions. Given the high accident rates, further research to investigate training strategies to offset delay effects clearly is necessary.

Adult↗

PubMed1995

Visual performance effects and user acceptance of the M43A1 aviation protective mask frontserts.

BACKGROUND: The initial M43 aviation protective mask was fielded without provisions for optical corrective devices. Contact lenses, an interim solution, were not entirely acceptable since a small segment of the population could not be fitted adequately with contacts. This study evaluated visual performance affects and user acceptance of the M43A1 mask with frontsert correction modifications. METHODS: The investigation was divided into three phases: 1) a helicopter simulator evaluation designed to experimentally test the suitability of the M43A1 frontserts, both in single vision and bifocal forms, for use in the aviation environment; 2) a static cockpit evaluation, designed to identify aircraft-specific problems with the frontsert system; and 3) an inflight evaluation to examine the stability and usability of the frontserts under actual flight conditions. The subjects were 30 U.S. Army aviators (28 men and 2 women). RESULTS: Objective data from flight simulation evaluations suggested there were no significant differences between flight performance with and without the mask, despite refractive status. Subjective data from static and flight evaluations reflected positive user acceptance of the new mask and frontserts. Problems may exist in smaller cockpits (OH-58 A/C, D), but evidence suggested that this may have been an artifact resulting from testing the mask while wearing protective body armor. CONCLUSIONS: Within the range of flight conditions and profiles examined, the M43A1 frontsert system meets U.S. Army aviation needs for optical correction when mission requirements dictate flying with chemical-biological protective masks.

Adult↗

PubMed1992

Phase shifts and the square-wave illusion.

When observers view a vertical triangle-wave luminance profile, they often report a square-wave illusion with a depth component, resembling a corrugated surface. Alternate bars seem to be in front of or behind adjacent bars and the surface appears to be illuminated from the right or left. These perspectives alternate with continuous viewing. One explanation for this illusion stems from the notion of instability among phase-selective mechanisms. Two experiments (1 and 3) were designed to determine whether systematic phase shifts introduced between the fundamental and the odd harmonics of the waveform would lead to a systematic bias of the illusion. The results indicated that a significant bias occurred when a phase shift as small as 9 deg was introduced, and that the bias from the phase shifts was more powerful than previous reports of drift-induced bias. There was a highly significant effect of direction of phase shift and the corresponding perceived direction of illumination. Another experiment (2) was designed to determine if illusional cues within the phase-shifted profiles aided phase discrimination. The results indicated that experienced subjects, presumably using cues within the profiles, discriminated between the stimuli significantly better than did naive subjects. These data support the role of phase in the square-wave illusion, but they also raise questions about the role of contrast changes in local regions of the stimulus.

Adaptation, Ocular↗