There is only one psychology, no specialties, but many applications.

Asserts that students who today receive a PhD degree via matriculation in a university department of psychology study the same principles, processes, and core content of the discipline regardless of the specific area of application they are pursuing. The broad content, processes, and principles that are the essence and core that differentiate psychology from physics, economics, history, and other cognate disciplines have remained the same since psychology first became a university discipline 100 years ago. It is also asserted that although many psychologists believe there currently exist bona fide specialties in psychology, neither the American Psychological Association nor most other societally relevant institutions have accorded such specialties de jure recognition. Although informal de facto recognition of specialties already exists, several other stages in the evolution of a specialty must (and very likely will) occur during the next decade before society accords specialties in psychology more formal, quasi-legal, de jure recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)