Date of Award
Master of Science (MS)
Based on extensive psychological and embryological research, neurohormonal theory proposes that males and females develop in sexually dimorphic patterns, in large part, because of differential androgen exposure during prenatal development (Kimmel & Weiner, 1995). Likewise, the theory suggests that variations in sexual orientation are also related to differential androgen exposure in prenatal life (Robinson & Manning, 2000). This study examined the ratio of the length of the second finger (2'1 digit) relative to the fourth finger (4th digit), also referred to as 2D:4D, and its relationship to same-sex erotic fantasy. These ratios are sexually dimorphic and are a presumed correlate of prenatal androgen exposure (Manning 1998a, 1998b, 1999, 2000). In addition, many sexually dimorphic disorders show seasonal birth patterns and therefore birth seasons were investigated as a potential correlate of 2D:4D ratios (Aschauer, Meszaros, Willinger, & Reiter, 1994; Badian, 1984). Results of this study indicated that women were much more likely to report fantasizing about both sexes, compared to men, and that women had significantly greater 2D:4D ratios, This difference in fantasizing may suggest that women may experience less societal restraint than men in terms of reporting sexual orientation (Kimmel & Weiner, 1995). Results also indicated that there was a trend for 2D:4D ratios to vary according to the sexual orientation of one's fantasies. Finally, results also showed that 2D:4D ratios did not vary according to birth season. The results are discussed in the context of current knowledge regarding digit ratios.
Lloyd, Rachel, "BIOLOGICAL CORRELATES OF SAME SEX EROTIC FANTASY AND DATE OF BIRTH: AN EMPIRICAL STUDY OF 2D:4D RATIOS" (2009). Electronic Thesis Collection. Paper 184.