Alternative explanations, such as those by functional linguists, have been sought in language processing. It is suggested that the brain finds it easier to parse syntactic patterns which are either right or left branching, but not mixed. The most widely held approach is the performance–grammar correspondence hypothesis by John A. Hawkins who suggests that language is a non-innate adaptation to innate cognitive mechanisms. Cross-linguistic tendencies are considered as being based on language users' preference for grammars that are organized efficiently, and on their avoidance of word orderings which cause processing difficulty. Some languages however exhibit regular inefficient patterning. These include the VO languages Chinese, with the adpositional phrase before the verb, and Finnish which has postpositions; but there are few other profoundly exceptional languages.