The stimuli were derived from a 200-ms harmonic complex tone with nominal F0 of 200 Hz, containing harmonics 1 to 12. The components had random starting phases (selected afresh for each stimulus presentation) and each component was presented at 50 dB sound pressure level (SPL). In context trials, one randomly chosen interval contained a complex tone with F0 = 200 Hz, while the other interval contained a complex with F0 = 200 Hz + ΔF0. In condition UNREL3, the 3rd harmonic (and the 7th, 9th, and 12th harmonics) was replaced by a noise band (see below) of equal rms level (50 dB SPL); the overall width of each noise band was 10 % of the nominal component frequency (NCF). The NCFs were identical in the two intervals; they were equal to r times (200 Hz + ΔF0/2﻿), where r corresponds to the harmonic rank of the component. In condition UNREL4, stimuli were the same as in UNREL3 except that the fourth instead of the third harmonic was replaced by a noise band. Thus, in context trials, either the 3rd or the 4th harmonic (plus the 7th, 9th, and 12th harmonics) was non-informative for the task at hand and, as feedback was provided in the context trials, listeners might learn to reduce the weighting of information from these non-informative components/frequency regions. Noise bands rather than sine tones were used to create non-informative components because the pitch of a noise band with center frequency f is less clear than that of a sine tone with frequency f and discrimination of noise bands with center frequencies around f is poorer than discrimination of sine tones with frequencies around f (Moore 1973a). The 7th, 9th, and 12th harmonics were replaced by noise bands in addition to the “target component” (either the 3rd or the 4th) in order to prevent perceptual segregation of that component. The test trials were identical in the two context conditions. For these, the complex tones in the two intervals both had an F0 of 200 Hz + ΔF0/2 , i.e., their F0 was halfway between the low and the high F0s of the two stimuli in the context trials, and no harmonic was substituted by a noise band. The complex tone in the first interval was perfectly harmonic. The complex in the second interval had randomly and with equal probability either its third or its fourth harmonic mistuned by a small amount (randomly either up or down in frequency with equal probability). Figure 1 shows a schematic of a possible trial sequence for condition denoted UNREL3, in which the third component was uninformative in the context trials. The percentages of mistuning of harmonics 3 and 4 and ΔF0 were determined individually for each listener in a preliminary experiment (see below).