To test whether groups showed a population bias of lateralization,
we conducted one-sample t tests using the software package
SPSS 16.0 (SPSS Inc., Chicago, IL, U.S.A.). In addition, to investigate
whether differences in duration of exposure to testosterone
affected the laterality index, a linear regression analysis was performed
using SPSS 16.0 (http://www.gnu.org/software/pspp/). All
tests were two tailed and significance levels were set to a < 0.05.