Insofar as there is any difference between being gullible and being manipulated I suppose that lies in the implication that a gullible person is particularly easy to manipulate. That is a very subjective distinction - in practice it would come down to whether someone is more easily manipulated than I think I am myself. How long is a piece of string?

If the alternative to being gullible is to be cynical, there is something to be said for being gullible. But the fact that all of us are gullible compared with someone else implies that in virtually all circumstances we should not be held too rigidly to our initial decision. For some reason it seems to be felt by some people that this should not apply in the case of a referendum in which we have relinquished significant rights.