Inconsistent handedness is linked to more successful foreign language vocabulary learning.

The study examined correlations between incidental learning of foreign words and interhemispheric connectivity, operationalized as consistency of hand preference, using pooled data of five experiments on adult foreign language learning (N = 242). Inconsistent hand preference was found to be positively correlated with vocabulary learning even after effects of cognitive variables (verbal working memory capacity and nonverbal IQ), identified previously as predictive of successful foreign-language vocabulary learning, were partialled out. This observed relationship between handedness consistency and vocabulary learning persisted when left-handed and right-handed individuals were analyzed separately, and there was no overall difference in performance between left- and right-handers. The findings confirm an association between degree of handedness and verbal episodic memory.