Detection of Known Signals in Arbitrary Backgrounds
Final technical rept. 1 Sep 1987-30 Sep 1990
BOYS TOWN NATIONAL RESEARCH HOSPITAL OMAHA NE
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This research program examined the large detrimental effects of masker uncertainty of the detection of a simple, known target signal. The basic task was the detection of a 1000-Hz sinusoid presented simultaneously with maskers composed of a few sinusoidal components whose frequencies were changed with each presentation. The masker properties were such that it is difficult to account for the results with traditional detection models which posit the use of a single filter centered at the signal frequency. The goal of this research was to understand the conditions under which performance is degraded by masker uncertainty, the processes involved, and whether procedures or cues could be identified to aid performance. Overall, the masking produced by uncertainty 1 showed large individual differences and training effects 2 was observed over a much greater range of conditions than expected and was largely independent of energy in a critical band around the signal 3 was reduced by procedures and cues which aid stimulus comparisons or memory and by temporal differences between stimuli 4 showed nonlinear additivity of masking with broadband noise and 5 showed much larger effects for frequency uncertainty than for uncertainty in overall masker level or component amplitudes.