Contralateral cueing effects in backward masking.

The role of stimulus uncertainty in backward masking was investigated using a Monaural Detection with Contralateral Cueing (MDCC) paradigm. Cues temporally synchronous with and phase locked to the signal (20-ms segment of 500-Hz sinusoid) reduced backward masking, with the amount of reduction being independent of the phase relationship between the cue and the signal. Band-limited noise cues synchronous with the signal also reduced the amount of backward masking, with cue bandwidth having only a small differential effect on the amount of reduction. The important parameter of the cue in reducing backward masking was the temporal synchrony between the cue and the signal; a silent gap in a broadband noise served as an effective cue. These results confirm that, unlike simultaneous masking, backward masking involves a high degree of temporal uncertainty.