There is an emerging pattern developing in the last few episodes. I was bothered by Jack's slow healing forehead injury. Then we have the Jin bump in the same place. Claire was blown up in a barracks house. Sayid was brain dead in the temple. Now we have Sun running into a tree branch and having an injury in the same place (frontal lobe). I am beginning to wonder if these head injuries are connected to the manipulation of the characters by either Jacob or MIB.
The executive functions of the frontal lobes involve the ability to recognize future consequences resulting from current actions, to choose between good and bad actions (or better and best), override and suppress unacceptable social responses, and determine similarities and differences between things or events. Therefore, it is involved in higher mental functions.
The frontal lobes also play an important part in retaining longer term memories which are not task-based. These are often memories associated with emotions derived from input from the brain's limbic system. The frontal lobe modifies those emotions to generally fit socially acceptable norms.
It is clear that Flocke (MIB) does want to people not to recognize what he is up to, to mask a person's choices between what is good and what is bad, with the emphasis on unleashing socially unacceptable responses. This may be a loophole: Jacob or MIB cannot make anyone do something against their free will, but MIB may put characters in a position not to know any better.