After various studies in the past had already suggested that 2D:4D digit ratio could be linked with the Big Five personality dimension Extraversion / Introversion, a new experimental study shows how the finger ratio combined with hand shape produces highly significant results.

The picture above displays a schematic presentation of the results: e.g. the ‘+’ and ‘-‘ signs show the proportional tendencies in the hands of Extraverts and Introverts. Details regarding the underlying results are presented in the article:

Extraversion associated with 2D:4D digit ratio, finger length & hand shape!

After various digit ratio studies found conflicting results related to Extraversion & sensation seeking (most pointed into the direction of a negative correlation), a new Dutch 2012 study suggest that other finger lengths require to be taken into account in order to find more clear results!

 The (unpublished) results from a female only suggest that low 2D:4D digit ratio + long pinky finger are much more often found in the hands of ‘extroverts’ (8 out of 40 hands = 20%), while this combination is rarely seen in the hands of ‘introverts (0 out of 28 hands = 0%).

Additionally, a high 2D:4D digit ratio with short pinky finger is much more common in the hands of ‘introverts’ (5 out 28 hands = 18%),  compared to the hands of ‘extroverts’  (3 out of 40 hands = 7.5%).

More details:

13 Hand signs for Extraversion / Introversion