But still, one would suspect that tones differing in pitch could be reliably judged as different when they are different and as the same when they are the same. This kind of judgment does not require absolute memory of pitch, just relative memory. The task used here, however, shows that even this task can be difficult for many people, particularly for those with no training in music. On each trial, a target tone and a test tone are presented with five distracter tones between them. The research participant's job is to judge whether the target and test tones are the same or different.
Performance is measured as percent correct.
The tones used in this experiment were created as pure tones ranging from 220 Hz to 880 Hz. There are 25 tones in all, equally spaced across the interval. Test tone selection is constrained to be either the same as the target tone or different by two semitones. Thus the same 12-tone set is used when choosing a target tone but the choice is not random. Selection is random with the constraint that no tone can repeat as a distracter on any one trial.