Target Detection in Homogeneous Noise Backgrounds Using a Time/Bearing Display Format

摘要

Analysis of subjective studies of contrast and detection thresholds in a black and white CRT display presenting rectangular targets in a homogeneous noise background indicate that these thresholds are invariantly related with respect to changes in bias or even to changes in the transfer characteristic of the display device so long as changes in the input signal-to-noise ratio are small compared to the bias voltage. The results suggest a reduction rate in detection threshold of 1.5 dB per doubling of the target area for targets whose images lie entirely within the fovea. For larger targets this rate rapidly decreases and approaches zero for target subtenses of approximately 10 degrees. The observed threshold reduction rate of 1.5 dB per doubling of target area is considerably smaller than previously published values of 2.2 dB per doubling. Effects of target presentation time are considered and are suggested as a possible explanation for discrepancies between the present and previously reported measurements. (Author)