All they can think is anger and just blind rage towards anyone who isn't infected yet. It's their will to chase people to kill them to release some of the anger. If they couldn't reason I think it would be a bit harder for the black guy to get to the window to attack the other soldiers, otherwise he would have just stood there in the courtyard till someone actually came out there. If it doesn't involve releasing their rage, the infected won't care about it, like eating. They don't feel the pain of anything, just rage, so they don't know they are starving.

When something is undead, it has to die. It’s a reanimated body. Their mind is full of rage, they aren't dead in anyway. The original definition of zombie is a soulless, mindless body brought back from the dead using voodoo. One of the main things is it has to be UNDEAD, not living. Do you even know what a berserker is? If you don't then there is no real point in trying to act like you understand this movie at all.