26, although I wasn't familiar with all the tunes.
Most of those examples used tunes with distinctive rhythmic signatures. Since this is a test that focuses on pitch, I'm wondering how much the rhythmic identity of a tune assists or distracts from pitch identification. Is one more or less able to identify wrong pitches due to their specific placement within metre? What would happen if this test were to use tunes with less variability in changing note durations. Eg: hymn tunes primarily made up of quarter and half notes?
The "wrong" tunes in that test also tended to use similar methods of modifying that tune: a rough modulation to a remote key, whimsical intervalic jumps in primarily scale-tone based tune (tritones, etc.), rough modulation in the center of the excerpt with return to the home key at the cadence. What would happen if one were to use more musically stable modifications, such as changing the modality of the entire excerpt? Eg: major tune played in minor, minor tune played in lydian mode, major tune played in an octactonic mode.