Corpus Callosum
It has been claimed that the human corpus callosum shows sex differences, and in particular that the splenium (the posterior portion) is larger in women than in men. This was based on old data from the study of cadavers. More recent data from MRIs does NOT support this.
The widespread belief that women have a larger splenium than men and consequently think differently is untenable.

However, there have been more recent studies showing differences in the the number of axons by axon diameter and locaation at different ages in men and women.
See:
Sex differences in the corpus callosum of the living human being
Corpus callosum abnormalities in psychopathic antisocial individuals. [Arch Gen Psychiatry. 2003] - PubMed - NCBI
Cuprizone demyelination of the corpus callosum in mice correlates with altered social interaction and impaired bilateral sensorimotor coordination, American Society for Neurochemistry (ASN), 1/2009 | ResearchGate

David Whitney, a visual psychophysicist at the University of California-Davis,* recently described this phenomenon in the lab. The results, published in Nature ("The influence of visual motion on fast reaching movements to a stationary object"), showed that a field of background motion can bias hand movements in the direction of that motion.

See story at slate.com