Prenatal hormonal exposure (2D:4D ratio) and strength of lateralisation for processing facial emotion

• This study examines the relationship between 2D:4D ratio and emotion lateralisation.
• More prenatal T (low 2D:4D) predicts stronger right hemisphere lateralisation.
• Findings only for processing of disgust, happiness, sadness and surprise.
• No sex differences in the relationship between 2D:4D ratio and lateralisation.

It has long been suggested that prenatal hormonal exposure influences the development of functional brain asymmetry, however there is relatively little research directly examining this association in non-verbal cognitive functioning. In this study the relationship between 2D:4D ratio and strength of lateralisation to the right hemisphere for processing facial emotion is examined in a large sample (N = 475) of males and females. Left hand 2D:4D ratio was a significant predictor of strength of right hemisphere lateralisation for processing facial emotion, but particularly for the processing of facial expressions of disgust, happiness, sadness and surprise. Individuals with lower 2D:4D ratios, indicating higher levels of prenatal testosterone exposure, tended to be more strongly lateralised to the right hemisphere for the processing of both positive and negative facial emotion. However, there was no sex difference in this relationship, suggesting that the influence of prenatal testosterone is the same for males and females.