Conspicuity of Aids to Navigation. 1. Temporal Patterns for Flashing Light
Abstract
Mariners frequently have trouble picking out lighted aids to navigation in harbors and other areas that have a high density of background lights. The U.S. 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 a light that is not flashing. This investigation sought to improve conspicuity by finding the optimal flash characteristics for a light on a background of steady lights. Twenty observers searched for a flashing point source of light among backgrounds of steady lights of various numerosities on a computer controlled CRT screen. They indicated which of the five screen sectors contained the flashing target, and the computer recorded the accuracy and response time. Targets were flashed at the rates of 1, 2, and 3.85 Hz, each at duty cycles of .3, .5, and .8 (proportion of total time on). After a brief practice period, each observer completed 360 trials in a single one-hour session. An ANOVA showed significant effects of frequency, duty cycle, and background light density. Search time increased as the number of background lights increased. Conspicuity improved as frequency increased and as duty cycle decreased. The flash pattern that provides the greatest conspicuity consumes the least amount of electrical energy, an important consideration for an aid to navigation. The results can be used as guidelines for the flash characteristics of lighted aids to navigation.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 03, 1993
- Accession Number
- ADA264626
Entities
People
- Kevin V. Laxar
- Sandra L. Benoit
Organizations
- Naval Submarine Medical Research Laboratory