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Sandra L. Benoit

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Publications by Sandra L. Benoit (bibliography)

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1995
 
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Benoit, Sandra L. and Laxar, Kevin (1995): Spatial Configurations for Flashing Lights as Marine Aids to Navigation. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. p. 948.

Lights used as marine aids to navigation are typically point sources that are easily confused with the background clutter of lights on shore. The problem is one of relative conspicuity of signals, the likelihood that a stimulus will be noticed. Previous studies have shown that conspicuity is affected by such physical characteristics of the target as size, luminance, contrast, movement, spatial characteristics, and number of distractors in the surround. Practical considerations limit the use of increases in size, luminance, contrast, and motion characteristics for application to navigational lights. The present research was conducted to determine how well lights of various spatial configurations stand out from a background of lights, to serve as a basis for the design of lighted aids to navigation. In a prior experiment (Laxar and Benoit, 1993), we found that a flash frequency of 4 Hz and a duty cycle (proportion of time lit) of .5 maximized conspicuity of a point source target light against a background of small lights. We used this temporal characteristic in the present study. The measure of conspicuity was the response time for an observer to find a flashing target among backgrounds of steady lights on a CRT display. Twenty observers participated. Nine targets were tested, each at three temporal flash patterns and four background light densities. ANOVAS showed significant effects of target, flash pattern, and background. Simultaneously flashing the target elements of two horizontal bars of light produced the greatest conspicuity, followed by two diagonal bars, and a triad of lights. The Flashing pattern, in which all segments of the target were on for 125 ms and then off for 125 ms, always produced the quickest response times and the fewest errors. Alternately flashing the elements of the target always produced the longest response times and the greatest number of errors. Overall, search time increased with the density of background lights, with the Flashing targets least affected, and the Alternating targets most affected.

© All rights reserved Benoit and Laxar and/or Human Factors Society

 
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Laxar, Kevin V. and Benoit, Sandra L. (1995): The Conspicuity of Flashing Lights as Marine Aids to Navigation. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 1380-1384.

Mariners frequently have trouble distinguishing lighted aids to navigation in areas with a high density of background lights. The Coast Guard is seeking ways to enhance the conspicuity, or likelihood of being noticed, of these aids. Literature has shown that a flashing light is more conspicuous than one that is steady. To improve conspicuity by determining optimal flash characteristics, we had 20 observers search for a flashing point of light among backgrounds of steady lights on a CRT screen. In single 360 trial sessions, observers indicated which of five screen sectors contained the flashing target, and accuracy and response time were recorded. Targets were flashed at 1, 2, and 3.85 Hz, each at duty cycles of .3, .5, and .8. An ANOVA showed significant effects of frequency, duty cycle, and background light density. Search time increased with number of background lights. Conspicuity improved as frequency increased and as duty cycle decreased.

© All rights reserved Laxar and Benoit and/or Human Factors Society

1994
 
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Orden, Karl F. Van, Benoit, Sandra L. and Osga, Glenn A. (1994): Adrenergic Stress and Performance on a Command and Control Task. In: Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting 1994. p. 991.

Performance on a simulated antiair (AAW) and antisurface-ship (ASUW) warfare task was examined as a function of task-independent cold air-induced adrenergic stress. Twenty subjects, trained and experienced in modern naval warfighting systems, completed the study. The 54-minute scenario task required subjects to seek out information on a tactical display regarding the appearance of new symbols, respond to questions regarding general symbol recognition, and respond to questions concerning specific, scenario dependent, symbol characteristics. Near the conclusion of the scenario, subjects were also ordered to fire missiles at designated targets and to fire missiles at targets of their own choosing. Performance on the task was recorded while subjects were exposed to room air temperatures of either 22{deg}C or 4{deg}C. The cold exposure paradigm produced an adrenergic stress response -- as indicated by significantly elevated pulse and norepinephrine levels. Results showed task performance was nearly identical for both groups for the scenario as a whole. However, during a 12-minute portion of the scenario when hostilities were simulated, the ambient and cold stressed groups demonstrated divergent behavioral response patterns; stressed subjects were more liberal with missile fire, and more conservative in their responses to the scenario dependent questions. The responses to the symbol recognition questions during the hostilities portion of the scenario were equivalent for both groups. These results are indicative of a shift in the allocation of cognitive resources as a function of adrenergic stress, and have implications for the development of complex human-machine interfaces.

© All rights reserved Orden et al. and/or Human Factors Society

 
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27 Jun 2007: Added
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May 25

Civilization advances by extending the number of important operations which we can perform without thinking of them.

-- Alfred North Whitehead

 
 

Featured chapter

Read the fascinating history of Wearable Computing, told by its father, Steve Mann

Read Steve's chapter !

 
 

Help us help you!