I think that positive messages can affect a person's self-picture, outlook, and behavior. I think this because when you receive positive messages you tend to strive to be a better person and it helps to shape you into a better person. Positive messages can include being congratulated on a job well done or simply being encouraged to tone up on skills that you may already have. If you receive positive messages then you tend have a better outlook on life and instead of always looking at the glass half empty then you will then look at the glass half full and that makes all the difference in that word.
A person is shaped by the feedback that they receive and depending on the type of feedback that a person receives. People who get the positive messages tend to exceed better because they want to keep doing a better job than what they are currently doing.
A persons self-picture is how they view themselves and when they receive great feedback then how they view themselves will improve.