Dear VU lectures have obviously designed or planned according to their requirements. First of all you should check the course outline or syllabus given by FPSC. Get a recommended book or a popular psychology book like Feldman or any other you can get your hands on , cross check the syllabus with the topics in the book you chose. Only then you would know where you stand with the prep. You can make the same comparison of syllabus with VU notes and you will find out the differences.
Also you should always remember mere slides cant get you 20 marks, maybe get you through the objectives but subjective questions have their requirements and without fulfilling them you cant pass the subject let alone score.