Adding Redundant Tonal Context Enhances Listener Sensitivity to Major vs. Minor Modes

In Western music, major and minor scales convey opposing moods (happy and sad, respectively), even though the distinction requires only a perceptually small alteration to a single pitch. Listener sensitivity to this communicative signal in music has been well documented, yet recent work indicates that most listeners cannot differentiate rapid major vs. minor pitch sequences, perhaps limited by pitch discrimination ability. The current paper explores this apparent contradiction. Exps. 1-2 replicated findings that most participants are insensitive to the distinction between major/minor pitch sequences in classification tasks. Insensitivity persisted despite increasing the relative occurrence of the differing pitch (Exp. 1) and using meaningful category labels (Happy/Sad vs. Type 1/2; Exp. 2). Exp. 3 eliminated classification demands by using a same/different discrimination task; scores improved overall, but most participants remained close to chance. However, discrimination improved when an invariant pitch compatible with both scales was added (Exp. 4). Exp. 5 explored the role of spectral context by comparing sequences of sine tones (no harmonics) vs. synthesized guitar tones (with harmonics). Participants performed better with guitar tones. These two studies suggest that richer auditory context (additional pitches, harmonics) increases sensitivity to the major/minor distinction. Exp. 5 also included an isolated target pitch discrimination task — testing discrimination of the critical pitch difference between major/minor stimuli — to explore the possibility of perceptual limitations on performance. Performance was considerably higher than on the full tone sequences, indicating that pitch discrimination alone is not a limitation for most participants.