Recognition of transposed melodies: Effects of pitch distance and harmonic distance

People easily recognize a familiar melody in a previously unheard key, but they also retain some key-specific information. Does the recognition of a transposed melody depend on either pitch distance or harmonic distance from the initially learned instances? Previous research has shown a stronger effect of pitch closeness than of harmonic similarity, but did not directly test for an additional effect of the latter variable. In the present experiment, we familiarized participants with a simple eight-note melody in two different keys (C and D) and then tested their ability to discriminate the target melody from foils in other keys. The transpositions included were to the keys of C# (close in pitch height, but harmonically distant), G (more distant in pitch, but harmonically close), and F# (more distant in pitch and harmonically distant). Across participants, the transpositions to F# and G were either higher or lower than the initially trained melodies, so that their average pitch distances from C and D were equated. A signal detection theory analysis confirmed that discriminability (d') was better for targets and foils that were close in pitch distance to the studied exemplars. Harmonic similarity had no effect on discriminability, but it did affect response bias (c), in that harmonic similarity to the studied exemplars increased both hits and false alarms. Thus, both pitch distance and harmonic distance affect the recognition of transposed melodies, but with dissociable effects on discrimination and response bias.