IMPROVER OPERATOR DETECTION PERFORMANCE CONSEQUENT TO THE USE OF OPTIMUM BIAS AND GAIN

Abstract

Abstract : Five experiments were undertaken using the visual display of a sonar stack. The first three were psychophysical in nature, undertaken to determine the effects of CRT bias (display brightness) and gain upon operators' target detection performance, at various ranges, with and without reverberations. Optimum values of bias and gain were determined. The fourth experiment was undertaken to determine values of CRT bias and gain considered optimum by experienced operators. In comparison with the values determined in the first experiment to be optimum, the average values of the experienced observers represented a performance loss of about 10 decibels. The fifth experiment compared target detection performance of 26 operators in searching for targets when (1), the display was at experimentally determined optima of bias and gain, with that when (2) the display was at values of bias and gain set by the operators. When experimentally determined values of bias and gain were employed, there was an improvement in the percentage of targets detected by a factor of 10, and one quarter as many false reports of targets were made. A brief survey conducted aboard seven ships in port indicated that the findings of the fourth experiment would have been virtually the same had the data been collected at sea. Consideration is given to several techniques which might be feasible in an operation setting for setting optimum bias and gain.