The main question was whether performance in the test trials was worse in the unreliable than in the reliable context condition. Figure 2 shows the mean d′ values (and standard errors across the seven listeners) separately for test trials in which the third harmonic was mistuned (group of two bars on the left) and for test trials in which the fourth harmonic was mistuned (group of two bars on the right). In both cases, d′ was lower in the unreliable context condition (white bars) than in the reliable context condition (black bars). This finding was confirmed by the results of a repeated-measures ANOVA which showed a significant main effect of the reliability of the relevant frequency information in the context trials [F(1, 6) = 9.28, p = 0.023]. There was no significant main effect of mistuned harmonic number [F(1, 6) = 0.02, p = 0.90] and, even though the effect of reliability was numerically larger for the fourth than for the third harmonic, the interaction between mistuned harmonic number and reliability of the relevant frequency information in the context trials was not significant [F(1, 6) = 3.33, p = 0.12]. On average, d′ was 8.8 % higher when the context was reliable than when it was unreliable (95 % confidence interval for the effect = [1.7 %, 16 %]). Thus, the observed effect on d′ was significant but small.FIG. 2Mean d′ values (and standard errors) across the seven subjects in test trials with the third (left two bars) and with the fourth (right two bars) harmonic mistuned in the unreliable (white bars) and reliable (black bars) context conditions. The standard errors are based on normalized data—to equate the mean performance across listeners—as inter-subject variance is irrelevant for within-subjects designs (Loftus and Masson 1994).