Fig. 2: Experiment 2—Numerosity Comparison Task.
From: A left-to-right bias in number-space mapping across ages and cultures
A Stimuli used in the Numerosity Comparison Task to represent 4, 12, and 36 dots. B A schematic representation of one exemplar trial in the Numerosity Comparison Task. In the Decreasing Task instruction, participants were instructed to press a central key as fast as possible (using their dominant hand) only when the test numerosity was smaller than the prime numerosity. In the Increasing Task instruction, instructions were reversed. In this trial, the test numerosity is smaller and appears on the right side of the screen, corresponding to an incongruent condition. All participants but the Himba tested in 2021 performed both tasks, in counterbalanced order. In the group of Himba tested in 2021, half the participants performed the task with the Increasing instruction and the other half with the Decreasing instruction. See Methods section. C In the implicit task (B) we measured participants’ performance in terms of a combined measure of speed and accuracy (Inverse Efficiency Score, IES), and we calculated the Congruency Effect for each Task instruction (see Methods section for the detailed analysis, and Data distribution in Fig. S2). In the graph individual points, mean values, standard errors of the mean, and significant pvalues are reported for each group and Task instruction (Two-tailed one sample t test and two-tailed Wilcoxon signed rank test; Decreasing condition (red): Italian Adults: N = 47, p < 0.001, Himba Adults 2021: N = 33, p =0.004, Himba Adults 2022: N = 78, p = 0.026, Italian Preschoolers: N = 38, p = 0.008; Increasing condition (gray): Italian Adults: N = 47, p = 0.505, Himba Adults 2021: N = 26, p = 0.805, Himba Adults 2022: N = 78, p = 0.119, Italian Preschooler: N = 38, p = 0.421; see Tables 3, 4). Significance levels are defined as follows: * = pvalue <0.05, ** = pvalue <0.01, **** = pvalue <0.0001).
