Figure 2. Accurate classification of all three song types and cohort-wide, with no effect of age.

(a) Mean d-prime scores across all children show above-chance classification of each song type, independent of their response bias. (b) Above-chance sensitivity replicates for each age group, except for some of the healing song estimates whose 95% confidence-intervals crossed zero. Performance did not improve with age, either averaging across all song-types, or within dance, lullaby, or healing songs individually (ps > 0.05). As a reference, the rightmost triangular points depict performance in a similar experiment with 98,150 adults between 18 and 99 years of age (mean 31 years). Small differences in task demands make strict comparison to the children problematic, but qualitatively, they show comparable performance. In both panels, the circles indicate d-prime scores and the error bars indicate the 95% confidence intervals. In panel b, the three thick lines depict a linear regression for each song type and the shaded regions represent the 95% confidence intervals from each regression.