From Diversifying Economic Quality: A Wiki for Instructors and Departments
Choose introductory textbooks that better portray the diversity of the population.
There are over 2 million students who take an introductory psychology course because of major/minor requirements, general interest in the area, or as requirements of other majors. Thus, there is a huge influence that the introductory textbook has in the effort to recruit and retaining minorities into the field of psychology. The APA (American Psychological Association) commissioned the Textbook Initiative Work Group to develop a general guideline of 20 categories to help in this effort.
There isn't empirical research done on the any results of altering textbooks, but this is more of a guideline based on personal expertise and reading through current and previous textbooks to see what the best changes would be.
Trimble, Joseph, Stevenson, Michael, & Worell, Judith. (2003). Toward an inclusive psychology: infusing the introductory psychology textbook with diversity content. American Psychological Association.