Standard deviation of the decision variable.

Average estimates of the observed standard deviation of the decision variable (σ_FM) and the SD σ_NM that would result when the internal noise effective for maskers and targets were identical to the situation in quiet. If σ_FM>σ_NM then at least one of the internal noises was increased under forward masking (see the text). The SD estimates are plotted as a function of standard level and masker lateralization. Left panel: contralateral maskers. Right panel: ipsilateral maskers. Data of 6 listeners (see text). Squares: σ_NM. Circles: σ_FM. Error bars: 95% CIs.