The stimuli are schematically illustrated in Figure 1. The task was the same throughout the experiment. In a two-interval two-alternative forced-choice task, the listener was asked to indicate which of two harmonic complex tones had the higher overall pitch (residue pitch), ignoring individual components that might pop out. There were two conditions, which were tested in a blocked design. The two conditions differed only with regard to the context trials in which slightly different stimuli were presented in the two conditions (see below and Fig. 1); one condition was designed so that listeners experienced the third harmonic as non-informative (“unreliable”) in the context trials (condition “UNREL3”) and the other condition was designed so that the fourth harmonic was non-informative in the context trials (condition “UNREL4”). In the test trials, the same stimuli were presented in the two conditions. In test trials, either the third or the fourth harmonic was slightly mistuned upwards or downwards in the second interval, while all other harmonics were identical across the two intervals. Moore et al. (1985) showed that a slight mistuning of an individual harmonic in a complex tone leads to a small shift in the residue pitch of the complex; the residue pitch goes up when the frequency of the mistuned harmonic is increased and goes down when it is decreased from its nominal value. In context trials, which made up 60 % of all trials, feedback was provided. In test trials (40 % of all trials), no feedback was provided. The test trials were randomly interspersed with the context trials.FIG. 1Schematic diagram of a possible trial sequence for condition UNREL3. In context trials, harmonic 3 plus harmonics 7, 9, and 12 are replaced by non-informative noise bands. The difference in F0 between the low and the high cases can be most easily seen by comparing the positions of the high harmonics to the fixed position of the noise bands. Trial 1: context trial with higher F0 in first interval. Trial 2: context trial with higher F0 in second interval. Trial 3: test trial with identical F0s and fourth harmonic shifted upward in frequency. Trial 4: context trial with higher F0 in first interval. Trial 5: test trial with identical F0s and third harmonic shifted downward in frequency.