FURTHER STUDIES OF THE DETECTABILITY OF DEGRADED VISUAL SIGNALS

Abstract

Observers responded to abstract forms (quadrigons) in six experiments, under a signal detection paradigm. Duration of stimulus exposure was shown to have strong effects upon detection accuracy (two studies); immediate feedback of accuracy information to observers affected performance chiefly by influencing guessing bias, not sensitivity (two studies); images that had been blurred and then deblurred by means of an analog device were compared with unblurred originals, and the effects of the retrieval process (deblurring) were characterized quantitatively by a signal detection index (one study); and electroencephalographic correlates of signal detection responses were found to vary with performance accuracy and observer confidence (one study). Discussions of the theory of signal detectability and of electroencephalography, as tools in the study of image quality and of observer sensitivity, are included in the report.