How is a grating detected on a narrowband noise masker?

Thresholds were measured for detecting 4 cpd gratings added to maskers consisting of nine sinusoidal components spanning 1 octave around the signal frequency. Phases of all mask components were randomized on every presentation. To assess their importance, contrast differences were either rendered unreliable by introducing contrast jitter between-intervals, or eliminated by equating contrast energy within the octave band across intervals and trials. The deleterious effects of contrast jitter and the similarity of grating detection and contrast discrimination thresholds argues that contrast cues are being used. Those cues are not the only ones available, because contrast jitter has less than the expected effect, and equating contrast energy only raises threshold a few dB. Computer simulations reveal that there is sufficient information in several spatial pattern cues to support detection performance.