Negative hedonistic utilitarianism thinks of utility in terms of hedonic mental states such as suffering and unpleasantness.[6] Negative Average Preference Utilitarianism[15] makes the same assumptions on what is good as negative preference utilitarianism, but states that the average number (per individual) of preferences frustrated should be minimized. Versions of (negative) utilitarianism can also differ based on whether the actual or expected consequences matter, and whether the aim is stated in terms of the average outcome among individuals or the total net utility (or lack of disutility) among them.[16] Negative utilitarianism can aim either to optimize the value of the outcome or it can be a satisficing negative utilitarianism, according to which an action ought to be taken if and only if the outcome would be sufficiently valuable (or have sufficiently low disvalue).[17] A key way in which negative utilitarianisms can differ from one another is with respect to how much weight they give to negative well-being (disutility) compared to positive well-being (positive utility). This is a key area of variation because the key difference between negative utilitarianism and non-negative kinds of utilitarianism is that negative utilitarianism gives more weight to negative well-being.