Ask the Brains; November / December 2009; Scientific American Mind; by Terry Sejnowski; Robert O. Duncan; 1 Page(s)

Is it true that when we drive, walk or reach for something our brain performs calculations? Is this ability learned or innate?
—Helena Larks, San Francisco

Computational neuroscientist Terry Sejnowski of the Howard Hughes Medical Institute at the Salk Institute and the University of California, San Diego, answers:
Our brain is wired to perform calculations that let us judge how far away an object is when we walk or jump around or reach for a container of milk. Although this task may seem easy, it turns out that calculating depth is surprisingly complex.