Ferrier's mistake revisited, or when it comes to the brain, nothing is simple

To review the work of David Ferrier (1843-1928), the British pioneer in the localization of function in the cerebral cortex. In his experiments on monkeys, Ferrier mistakenly located the center for vision in the angular gyrus of the parietal lobe. What led him to this error?

Ferrier included details of his technique and many of his original laboratory observations in his published papers and books; these published works have allowed a reconstruction of his thought processes as he struggled to assess vision in untrained animals.

The occipital lobe lesions produced by Ferrier did not yield vision defects that were gross enough to be detected by observing a monkey's random behavior. On the other hand, the posterior parietal lesions produced by Ferrier did change a monkey's behavior in ways in which Ferrier misinterpreted as being due to induced blindness. Ferrier had probably induced visual neglect and a disinclination in the monkey to move its body, as well as actual vision disturbances in guiding voluntary limb movements.