Mary M. Connors

Groups in Exotic Environments

Publisher Summary This chapter focuses on groups of people in polar camps, submarines, space capsules, and other exotic environments that are defined by the characteristics of isolation, confinement, and risk. At the same time that exotic environments are becoming more salient, behavioral research on groups in exotic environments has almost ground to a halt. The chapter considers certain barriers to further advancement in which people involved in such groups may view psychological research as useless or counterproductive. The exotic environments of yesteryear have changed substantially, and many new exotic environments are available for study. Social and organizational psychology has changed immensely, and many new developments can be taken into account. The chapter illustrates those two theoretical models, the ecological and the behavioral, that have evolved around isolation and confinement research. As group level phenomena are supplemented by organizational level phenomena, open systems theory may be put to good use.

Luminance Requirements for Hue Perception and Identification, for a Range of Exposure Durations

This study investigated the effect of exposure duration on the luminances required to reach absolute, detection, chromatic, and correct-hue thresholds. Dominant wavelengths 642, 584, 521, and 468 nm were investigated by the method of constant stimuli, with 64.5- and 2.5-min-diam stimulus sizes, for a series of nine exposure durations ranging from 5 to 1413 msec. The results show that, for the small stimulus at brief durations, the luminance–exposure-time relationship approaches Bloch’s law for the absolute-, detection-, and chromatic-threshold functions. For the corresponding correct-hue function, and for all thresholds, brief durations, large stimulus, the slope of the function relating luminance to exposure duration is less than that predicted by Bloch’s law. The slopes relating luminance to exposure duration for the long exposures are greater for the small than for the large stimuli. There is a tendency for the two longer wavelengths to be seen at lower luminances than the two shorter wavelengths, for all thresholds and exposures. The extent of the differences among wavelengths changes as a function of the kind of threshold; the greatest difference occurs for the correct-hue threshold. Photochromatic intervals α and β are smallest for the 642-nm stimulus, over the range of durations. At this wavelength, the four thresholds can be described by a single function relating luminance and exposure duration. The largest photochromatic intervals α and β are found for the 521-nm stimulus. The results are discussed in terms of the relative action time among hues and the threshold-tritanopia hypothesis.

Luminance Requirements for Hue Perception in Small Targets

This study investigated the luminances necessary to perceive red (642 nm), green (521 nm), and blue (468 nm) at nine visual angles ranging from over 1° to 21 sec of arc diam. Monocular, foveal measurements were made by the method of constant stimuli at exposures of 44 and 700 msec duration. Three color-normals served as observers.The results show that, with sufficient luminance, these hues can be seen even for stimuli as small as 0.35 min of arc diam. Red is generally perceived at lower luminances than blue or green. There is an inverse relationship between stimulus size and luminance necessary for hue perception which can be represented as two linear functions. At small angles, the area-luminance slopes bracket, but tend to be somewhat larger than the slope predicted by Ricco’s law; at larger angles, the function resembles that predicted by Piper’s law. The change of function from approximately A · I=C to approximately A12·I=C occurs at higher visual angles for shorter exposures.

Relative Red-Green Sensitivity as a Function of Retinal Position

Hue cancellation was employed to obtain sensitivity curves for red and for green by the method of constant stimuli. Data were taken at the fovea, and at points every 2 deg along the lower vertical meridian of the visual field. The results show that sensitivity to red, relative to green, is highest at the fovea, and decreases as the peripheral angle is increased. The relative sensitivity to green is highest in the near periphery, from 2 to 10 deg from the fovea. Beyond this point it falls rapidly, and is no longer measurable at positions where red responses are still obtained.

Luminance requirements for hue identification in small targets.

Foveal luminance thresholds for identification of red (642 nm), yellow (584 nm), green (521 nm), and blue (468 nm) were determined by the method of constant stimuli for a range of small stimulus sizes and for two exposure durations. The luminances necessary for chromatic and absolute thresholds were also specified. The luminance required for chromatic threshold was found to be lowest for the 642-nm stimulus and highest for the 468-nm stimulus; the threshold for correct hue identification was found to be inversely related to wavelength. The ratios of the luminance necessary for hue perception to the absolute threshold ranged from 1.14 for the 642-nm stimulus to 1.51 for the 584-nm stimulus. The ratio of the luminance required for correct hue identification to the absolute threshold ranged from 1.32 for the 642-nm stimulus to 3.33 for the 521-nm stimulus. More reliable responses and fewer confusions in the hue identification were associated with the 642-nm stimulus than with the other wavelengths. The identification thresholds of this study are compared with the detection thresholds for similar targets.

Effect of Surround and Stimulus Luminance on the Discrimination of Hue

The effects of changes in the luminance of the stimulus and the surround on hue discrimination were experimentally investigated, using the method of constant stimuli. All observations were made at 550 mμ; the standard deviation was used as the measure of sensitivity. Surround luminance was found to have no effect on hue discrimination until the surround had three or more times the luminance of the stimulus. As the surround to stimulus ratios increased, the threshold rose sharply. Increase of the stimulus intensity over a range of 1.5 log units from the photopic threshold increased the discrimination threshold by an average of only about 2 mμ.

Human factors in spacecraft design.

This paper describes some of the salient implications of evolving mission parameters for spacecraft design. Among the requirements for future spacecraft are new, higher standards of living, increased support of human productivity, and greater accommodation of physical and cultural variability. Design issues include volumetric allowances, architecture and layouts, closed life support systems, health maintenance systems, recreational facilities, automation, privacy, and decor. An understanding of behavioral responses to design elements is a precondition for critical design decisions. Human factors research results must be taken into account early in the course of the design process.

Effect of Wavelength and Bandwidth of Red Light on Recovery of Dark Adaptation

Recovery curves were run following 1- and 5-min adaptation to wavelengths ranging from 595 to 670 mμ taken at 15-mμ intervals at a luminance of 100 ft-L. The effects of near-monochromatic and broad bandwidths were investigated. Recovery curves are in terms of time necessary to return to a predetermined dark-adapted threshold and to stated values above that threshold.After one minute of adaptation to a light of 610 mμ, recovery is faster than after exposure to an equally bright light of 595 mμ. Lengthening the wavelength causes no further reduction in recovery time. After five minutes of similar adaptation, recovery time is progressively shortened by lengthening the wavelength to 640 mμ. Further increases in wavelength result in recovery times equivalent to those of the 640-mμ adaptation. Spreading the bandwidth from near monochromatic to 30 mμ has no effect on subsequent recovery, although further broadening the bandwidth to include the shorter wavelengths results in reduced sensitivity for the 595-mμ setting. These findings are consistent with luminosity theory.

Differential color sensitivity in the purple region

Color discrimination was measured by the method of constant stimuli at eight points along a blue to red continuum. The standard deviations of judgments of color difference were used as the measure of discrimination. In terms of ratios of luminances of the components, the sensitivity throughout most of the purple region is relatively constant. There is some decrease in sensitivity at the blue extreme and a larger decrease at the red end. The results are plotted on a CIE x, y chromaticity diagram and compared with similar data of other authors.

A Survey Methodology for Measuring Safety-Related Trends in the National Airspace System

Making informed judgments about the effects of technological, human, or environmental changes on civil aviation requires reliable information. The National Aviation Operational Monitoring Service (NAOMS), a research project under NASA’s Aviation Safety Program, developed and tested a survey methodology designed to provide statistically reliable information on changes over time in safety-related events in the national airspace. Such information would aid decision makers in determining what areas required attention. To evaluate the NAOMS concept, data from nearly 20,000 randomly selected air-carrier pilots were collected over 3 years. Results demonstrate that the NAOMS approach can reliably identify changes over time in the rates of safety-related events.