I was planning on entering the BA (PNB) and noticed that the first year courses are the same for both the BSC and BA. If I wanted to switch 3rd year out of the BA to the BSC or vice versa how difficult would it be? And is it possible?

I'm currently in 2nd year PNB (B.A.), and Im planning on switching to B.Sc. from 3rd to 4th year (I.e. I plan on switching into the B.Sc. program by 4th year)

Short answer: It's not difficult to do; just make sure you have your prerequisites done. Of course, you're going to have to talk to an academic adviser. The psych adviser is Ann Hollingshead.

I'm feeling lazy right now, so my reply isn't too detailed. Tell me if you need any clarifications.

Transition from PNB(BA) to PNB(BSC) is actually pretty easy. As long as you have the chem and physics prerequisites, I believe, you should be able to switch over.