Accession Number : AD0689358

Title :   ASSESSMENT OF THE BROCA-SULZER PHENOMENON VIA INTER- AND INTRA MODALITY MATCHING PROCEDURES: STUDIES OF SIGNAL-LIGHT BRIGHTNESS,

Corporate Author : CIVIL AEROMEDICAL INST OKLAHOMA CITY OKLA

Personal Author(s) : Lewis,Mark F. ; Mertens,Henry W.

Report Date : OCT 1968

Pagination or Media Count : 13

Abstract : Signal lights are presented to an observer as flashes with finite duration; thus, the effect of flash duration on the apparent brightness of the signal is important. The relation of effective signal brightness to flash duration and luminance finds expression in the Broca-Sulzer phenomenon. This study was concerned with the effect of method of measuring brightness and with the effect of adaptive state of the eye on the Broca-Sulzer phenomenon. Subjects adjusted the luminance of test flashes 1 to 1000 msec. in duration to match either the loudness of a 500 msec. comparison tone (1000 Hz) or the brightness of a 500 msec. comparison flash. Comparison tone loudness were 75, 86, and 97 dB. Comparison flash luminances were 10, 100, and 1000 mL. In the light-adapted condition, a 1.5 sec. adapting flash was presented 2.5 sec. before the comparison flash. No adapting flash was presented in the dark-adapted condition. The Broca-Sulzer effect appeared only with the highest comparison stimulus intensities in both crossmodality matching and brightness matching conditions. This finding conflicts with the hypothesis that the Broca-Sulzer effect is obtained only when the procedure for measuring brightness involves a visual comparison stimulus. An interaction found between method of measuring brightness and adaptive state was also discussed. The findings are pertinent to the prediction of effective brightness of a signal since, under some conditions, apparent brightness does not increase steadily with increased duration but, rather, evidences a peaking effect. (Author)

Descriptors :   (*SIGNAL LIGHTS, BRIGHTNESS), (*VISUAL PERCEPTION, *BRIGHTNESS), AVIATION MEDICINE, CORRELATION TECHNIQUES, TIME, ADAPTATION(PHYSIOLOGY)

Subject Categories : Psychology
      Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE