Data_Sheet_1_Differential Placing of Flexion Creases Contributes to Sex Differences in the Second-to-Fourth Digit Ratio (2D:4D).xlsx

The present research examined whether differential placing of the basal flexion creases contributes to the occurrence of sex differences in digit ratio (2D:4D) derived from palmar digit lengths. The ratio of palmar-to-dorsal digit length, a measure of the placing of the basal flexion crease in the finger, was derived for the digits 2 and 4 of the right hand in two independent samples (Study I: N = 100; Study II: N = 200), in accordance with discovery-replication sample approach. The results show that men have lower palmar-to-dorsal digit ratios than women, and this effect is significantly stronger for digit 2 than for digit 4. Thus, the present study supports the likelihood that differential placing of flexion creases in the digits contributes to the occurrence of sex differences in palmar 2D:4D. In addition (Study II), the measurement procedure assessing the placing of flexion creases was validated. In conclusion, this evidence highlights potential conceptual shortcomings and technical limitations in the measurement conventions and methods currently employed in the field of 2D:4D research.

本研究旨在探讨指基底部屈纹的位置差异，是否会导致由掌侧指长计算得到的指长比（2D:4D）出现性别差异。本研究以掌侧-背侧指长比作为指基底部屈纹位置的衡量指标，采用发现-重复样本研究范式，对两个独立样本（研究一：N=100；研究二：N=200）的右手第二指与第四指分别计算该比值。研究结果显示，男性的掌侧-背侧指长比显著低于女性，且该效应在第二指上的表现强于第四指。据此，本研究支持指部屈纹的位置差异会导致掌侧2D:4D指长比出现性别差异这一可能性。此外，研究二还对评估屈纹位置的测量流程进行了效度验证。综上，本研究结果揭示了当前2D:4D研究领域所采用的测量规范与方法，存在潜在的概念缺陷与技术局限。