Fig. 1: Experiment 1—Ordering Card Task.
From: A left-to-right bias in number-space mapping across ages and cultures
A A picture taken on the field of one Himba participant during the Ordering Card Task. In this task, participants were asked to order 10 cards, depicting 1–10 dots, on the table in front of them, such that they would look in order. No other instruction was given. B Percentage of choice for each type of spatial arrangement in the four groups. Lateral line (red) refers to a lateral disposition, Random (brown) to an absence of identifiable configuration (e.g. random scatterplot), Sagittal/Diagonal (orange) to non-lateral lines, and Two Dimensional (yellow) to a configuration which was identifiable but not linear (i.e. grid, square, circle; Table S1). C Kendall Tau correlation coefficient between ideal left-to-right order and participants’ disposition was calculated: negative values indicate leftward bias, positive values indicate rightward bias, and values close to 0 indicate not-ordered mappings (see Methods section for a detailed explanation of the analysis). For all groups, the mapping distributions (red) are different from the chance distribution (gray; Two-tailed two-sample Kolmogorov-Smirnov goodness-of-fit hypothesis test; Italian Adults: N = 38, p < 0.001, Himba Adults 2021: N = 60, p < 0.001, Himba Adults 2022: N = 70, p < 0.001, Italian preschooler: N = 28, p < 0.001). Black dots and whiskers show the mean mapping scores and the standard error of the mean. Only Italian Adults showed a consistent left-to-right preference at group level (Two-tailed one-sample Wilcoxon signed rank test; Italian Adults: N = 38, p < 0.001, Himba Adults 2021: N = 60, p = 0.257, Himba Adults 2022: N = 70, p = 0.805, Italian Preschooler: N = 28, p = 0.188; Table 1).
