Decision-theoretically speaking, there's no difference between punishment and lack-of-reward. (Von Neumann–Morgenstern utility functions are really only defined up to an affine transformation: if your behavior is described by u(x), then v(x) := au(x) + b does just as well.) Psychology isn't like that; punishment and lack-of-reward are very different things—although not quite so different as one might think. In an environment where behavior X is rewarded with praise and status, and behavior Y is ignored—not punished, not condemned, but ignored—what kind of mind would it take to persist in behavior Y? It would either have to be very stubborn, unshakeably convinced in the righteousness of Y, or very stupid, desperately willing to endlessly chase a satisfaction that will never, ever come.