In the case of uncertainty
is what is considered the most likely to happen. An expectation, which is a belief
that is centred on the future
, may or may not be realistic. A less advantageous result gives rise to the emotion
. If something happens that is not at all expected it is a surprise
. An expectation about the behavior or performance of another person, expressed to that person, may have the nature of a strong request, or an order.
Particularly in social sciences including game theory, expectation plays one of the central roles. In game theory, a Nash equilibrium constitutes a correct and stable set of expectations held by the players. Various other solution concepts of games such as rationalizability have been proposed according to how much knowledge players have on the expectation of other players' actions.
Emotion and Adaptation
In Emotion and Adaptation
(Oxford University Press, 1991), Richard Lazarus asserts that people become accustomed to positive or negative life experiences which lead to favorable or unfavorable expectations with regard to present and near-future circumstances. Lazarus notes the widely accepted, philosophical principle that "happiness depends on the background psychological status of the person -- that is, the overall pattern of expectations and existential mood -- and cannot be well predicted without
reference to" one's expectations [italics mine].
Also with regard to happiness or unhappiness, Lazarus notes that "people whose objective conditions of life are those of hardship and deprivation often make a positive assessment of their well-being," while "people who are objectively well off... often make a negative assessment of their well-being." Lazarus argues that "the most sensible explanation of this apparent paradox is that people... develop favorable or unfavorable expectations" that guide such assessments.