is this is mandatory that we have to done our bsc/ba in psychology to take addmission in M.sc/M.A psychology???
You can switch over the subjects in which you are doing Masters but it follows the one condition.
If you are a science stream student then you cannot switch over to humanities or other stream in Masters.
Same applies if you are a humanities student you cannot pursue science stream course in Masters.
Your admission into B.sc / B.A. Masters course depends upon in which stream you are doing graduation right now.
Hope it helps.
Best regards