A comparison between common marmosets (Callithrix jacchus) and human infants sheds light on traits proposed to be at the root of human octave equivalence

Abstract

Two notes separated by a doubling in frequency sound similar to humans. This “octave equivalence” is critical to perception and production of music and speech and occurs early in human development. Because it also occurs cross‐culturally, a biological basis of octave equivalence has been hypothesized. Members of our team previousy suggested four human traits are at the root of this phenomenon: (1) vocal learning, (2) clear octave information in vocal harmonics, (3) differing vocal ranges, and (4) vocalizing together. Using cross‐species studies, we can test how relevant these respective traits are, while controlling for enculturation effects and addressing questions of phylogeny. Common marmosets possess forms of three of the four traits, lacking differing vocal ranges. We tested 11 common marmosets by adapting an established head‐turning paradigm, creating a parallel test to an important infant study. Unlike human infants, marmosets responded similarly to tones shifted by an octave or other intervals. Because previous studies with the same head‐turning paradigm produced differential results to discernable acoustic stimuli in common marmosets, our results suggest that marmosets do not perceive octave equivalence. Our work suggests differing vocal ranges between adults and children and men and women and the way they are used in singing together may be critical to the development of octave equivalence.Research Highlights A direct comparison of octave equivalence tests with common marmosets and human infants Marmosets show no octave equivalence Results emphasize the importance of differing vocal ranges between adults and infants

Do rats ( Rattus norvegicus ) perceive octave equivalence, a critical human cross-cultural aspect of pitch perception?

“…However, there is a complication here. In a previous head-turning study with common marmosets ( Callithrix jacchus ), members of our group found no evidence of octave equivalence [39]. The study used a procedure that was adapted from a study with human infants [31] using a habituation/dishabituation paradigm similar to the one used in the study presented here.…”

Music, a piece of many puzzles in developmental science

“…Another compares children's associations between space and pitch across two non-English languages, Dutch and Turkish (Dolscheid et al, 2023). An examination of the biological basis of octave equivalence perception in common marmosets (Wagner et al, 2023) provides a comparative perspective, as does work examining the interplay between biological predispositions and developmental experiences in shaping the temporal patterning of birdsong (James et al, 2023). Contributions like these are essential for a comprehensive developmental science.…”