Informational masking: counteracting the effects of stimulus uncertainty by decreasing target-masker similarity

Previous work has indicated that target-masker similarity, as well as stimulus uncertainty, influences the amount of informational masking that occurs in detection, discrimination, and recognition tasks. In each of five experiments reported in this paper, the detection threshold for a tonal target in random multitone maskers presented simultaneously with the target tone was measured for two conditions using the same set of five listeners. In one condition, the target was constructed to be "similar" (S) to the masker; in the other condition, it was constructed to be "dissimilar" (D) to the masker. The specific masker varied across experiments, but was constant for the two conditions. Target-masker similarity varied in dimensions such as duration, perceived location, direction of frequency glide, and spectro-temporal coherence. Group-mean results show large decreases in the amount of masking for the D condition relative to the S condition. In addition, individual differences (a hallmark of informational masking) are found to be much greater in the S condition than in the D condition. Furthermore, listener vulnerability to informational masking is found to be consistent to at least a moderate degree across experiments.