Minecraft 1.4.5, Minecraft 1.5.2, Snapshot 13w25c
Put the summary of the bug you're having here
I would expect villagers would behave in areas based off of effects such as light, mob presence, door presence, etc. However, they will completely disregard even the presence of zombies to go to the northwest corner of their box.
Steps to Reproduce:
1.produce a box with area between 25 and 100 square blocks
2.spawn roughly 8-12 villager in box
3.you can attempt to lure them in any way you want, but they will stay in the general northwest vicinity
Note: I did test without the pillars present, and got the same results.