The human brain has an overall leftward posterior and rightward anterior asymmetry (or brain torque). Theories that explain this apparent asymmetry violate other measurements. In humans, functional cerebral dominance is accompanied by subtle anatomical asymmetry. Chirality is also seen in the study of facial asymmetry. This darkening is responsible for the hemispheric albedo asymmetry mentioned above. Such asymmetry in emotional valence creates another bias in language. It may lead to mild degrees of growth retardation and limb asymmetry. A process called baryogenesis was hypothesized to account for the asymmetry. Chiral ligands are useful for inducing asymmetry within the coordination sphere. It can cause painless facial asymmetry, diplopia and enophthalmos. There should be no noticeable asymmetry. He has also postulated a theory on chronons and time asymmetry. Economists argue that the inefficiency results from information asymmetry. A 2002 study draws a relationship between caudate asymmetry and symptoms related to ADHD. Plagiocephaly is a diagonal asymmetry across the head shape.