When a baby smiles at you, it's almost impossible not to smile back. This spontaneous reaction to a facial expression is part of the back-and-forth that allows us to understand each other's emotions ...

If you have ever lifted a weight, you know the routine: challenge the muscle, give it rest, feed it and repeat. Over time, it ...

The human brain, as the seat of mental life—from the most complicated intellectual processes down to routine and unconscious bodily control—is necessarily enormously complex. The largest part of the ...