Detection of pulse signals in noise: The effect on visual detection of the area of the signal paint

The problem of trace-to-trace correlation is reviewed in the light of some physiological experiments on the relationship between the area of an illuminated patch and the contrast required for its detection. It is concluded that the improvement in detection of a signal in noise obtained by trace-to-trace correlation can be largely accounted for by the increase in the solid angle subtended at the eye by the signal ¿paint.¿