Associations among ratio of digit lengths (2D:4D), hand preferences, nonverbal intelligence, visual, auditory and verbal ability, motor skill and cerebral lateralization in healthy persons

In this study, the associations among the parameters of hand, foot and eye preferences, ratio of digit lengths (2D:4D), nonverbal intelligence (IQ), hand motor skill in man and women were aimed to investigate. A total of 439 volunteer participants aged 18 to 25 were included fort his study. The parameters were determined as folllows: Hand preference using `Edinburg Hand Preference questionnaire?, IQ point using `Cattell?s Culture Free Intelligence Test? and motor skill using `Nail Movement Test?. For parameter of eye preference, the eye used for key hole were questioned, for foot preference the foot used for kicking the ball as well as the presence of someone in the family who kicks the ball by left foot. Respective finger length from anatomic boundaries was measured using digital compass caliper and the ratios of (2D:4D) were calculated. Statistical analyses were carried out by using t test, chi square test and Pearson correlation test of SPSS 16.0 computer program.Right foot preference was found to be higher in women than men, while left and all foot preference was found to be higher in men than women. While no statistically significant difference was found between the lateralization coefficients, right and left hand ratios (2D:4D), and IQ points in both men and women; the value for motor skill was higher in women in comparison to men. A meaningful correlation was determined between right and left hand digit ratios (2D:4D) of participants without any gender preference. In women, a positive correlation was found between right hand ratio (2D:4D) and IQ point. On the other hand, in men, a positive correlation was found between left hand ratio (2D:4D) and IQ point. A positive correlation between lateralization coefficient and motor skill values was also been shown in men.In conclusion, hand motor skill was higher in women than the one in men. Digit ratios (2D:4D) were found higher in the ones having higher IQ points. This was particularly valid for different digit ratios (2D:4D) depending on the gender. Altogether, in light of this study it was concluded that the motor skills were higher in men who have more lateralization (towards right).