The perceptual reality of tone chroma in early infancy

In the framework of a habituation‐recovery paradigm, we presented 40 infants, aged 70–110 days, two cyclically repeating melodic sequences of pure tones. The habituation sequence, A B C A B C …, was the same for all infants; its component tones, A, B, and C, had a level of 80 dB SPL and respective frequencies of 736.7, 487.4, and 428.1 Hz. B and C were replaced by X and Y in the test sequence, A X Y A X Y …, which had three different versions, heard by three separate groups of infants. For each group, X and Y were 85 dB SPL and X Y was an exact musical transposition of B C at lower frequencies. The interval between B and X (and C and Y) was equal to 1003 cents for group 1 (N = 12), 1200 cents—i.e., one octave—for group 2 (N = 16), and 1389 cents for group 3 (N = 12). Significant reactions to the sequence change were observed in groups 1 and 3, but not in group 2. Young infants would therefore seem to perceive as strongly similar two pure tones one octave apart. This tends to support nativist explanations of the perception of tone chroma.