A molecular description of profile analysis: decision weights and internal noise.

Systematic inefficiencies and internal noise in a spectral profile discrimination task were investigated. Listeners detected a 1000-Hz sinusoid added in-phase to the central component of a complex consisting of 11 equal-intensity sinusoids. Parameters for a channel model that employs decision weights and internal noise were estimated with molecular psychophysical techniques. Maximum likelihood predictions of the model were generally within a few decibels of observed thresholds. The degree to which an assumption of ideal weights leads to overestimation of internal noise was also assessed.