Changes in the 6th edition of the "Publication Manual of the American Psychological Association" from the 5th edition include material relating to levels of heading, reduction of biased language, style details and referencing format. It's important for researchers seeking publication in the social sciences to follow the most recent edition.
Some changes represent evolving cultural mores, such as the suggestions to reduce what may be perceived as biased language. But these suggestions also aim to make research papers more specific, such as in referencing a patient group "older adults" instead of the possibly offensive and more ambiguous "the elderly." Other suggestions in this area include suggestions for more precise terms for groups that participate in research. Members should be addressed as "participants," given that they often take active roles in experiments, and not the more dehumanizing term used before, "subjects."
Other changes address formatting directly. For example, two spaces must follow a sentence-ending period instead of one space. The requirements for the font types in the level headings are, with only one exception, different variations of bold and italic lettering, as opposed the variation of italics and all caps in the 5th edition. The rationale for these changes is readability. Reference changes and additions in the 6th edition include requirements on how to incorporate electronic sources.