Hi SMalik I am working as a Lecturer in the discipline of psychology in one of the public sector universities of punjab. I appeared in CSS 2009 and attempted psychology.
As you have mentioned that
1. you do not have any background in psychology
2. your masters is in political science
3. CSS 2010 is your last attempt
keeping in view your above mentioned concerns, it is safe for you not to go for psychology as
1. it is a technical subject
2. it needs background knowledge
3.its syllabus is lenghthy
it might become impossible for you to grab high marks in psychology, no doubt, you can get good marks by good preparation but to be on safe side as its your last attempt so do not opt psychology rather go for some other relatively scoring subject.
I hope you would be satisfied.
Ahmad Bilal