It is also a sign of nervousness. Very often a person tries to answer somebody who has not yet finished speaking; before a sentence is completed the answer is given. Such an answer given to an incomplete idea is often wrong. What generally happens in such cases is that one takes all that comes from outside in life too much to heart, and allows these outer things and influences to penetrate one more deeply than they should. In this way one becomes sensitive, and out of this arises nervousness.