The legibility of Scotchlite vs. other materials was investigates. The target placard carried digits similar to those painted on presen-day aircraft. The study was conducted under night time conditions with a standard Air Force spotlight used for illumination of digits. In "experiments" I and II male college students, with normal near and distance vision, read sets of 5 digits which were exposed for 4 seconds per set. The digit-bearing placard were presented at viewing angles of 90 degrees, 60, 40, 27, 18 degrees. In Experiment I all digits were black and were placed against three different backgrounds: (a) reflex-reflective (Scotchlite); (b) white paint; (c) aluminium. The viewing distances were 144, 218, 330 and 500 ft. In this experiment the superiority of the reflex. reflective background was demonstrated at extreme viewing angles for all distances. The superiority of reflex-reflective background was also shown for all viewing angles at the 330-500 ft. distances. In Experiment II the legibility of digits made of reflex-reflective material placed against a black background was compared with that of black digits placed against a reflex-reflective background. The Scotchlite digits superimposed on a black background were found to afford superior legibility at extreme angles for the 250-ft distance and at all angles for the 500-ft. distance. At the 500-ft distance the greater legibility of the individual Scotchlite digits was demonstrated at the 40 degrees angle for all except the digits 8 and 0.
Abstract