This can depend on who is teaching Introduction to Psychology, since it is offered every semester, and is taught by many different faculty. Depending on who is teaching the course, the overlap can vary between roughly 5% and 20%. However, even those topics that are covered in both courses are typically treated with very different perspectives and specific material. More generally, the 80+% of non-overlapping material in these courses reflects differences in their respective fields. On one hand, cognitive science incorporates perspectives drawn from only some areas of psychology, and also includes tools and ideas drawn from computer science, linguistics, neuroscience, and beyond. In contrast, psychology incorporates perspectives drawn from only a small part of cognitive science, but also includes material related to clinical psychology, social and personality psychology, health psychology, etc. Many majors end up taking both of these courses, however, since Introduction to Cognitive Science is required for the major, while Introduction to Psychology is required in principle as a pre-requisite for many other psychology courses.