In economics, intertemporal choice is the study of the relative value people assign to two or more payoffs at different points in time.
Intertemporal choice was introduced by Canadian economist John Rae in 1834 in the "Sociological Theory of Capital".
Later, Eugen von Böhm-Bawerk in 1889 and Irving Fisher in 1930 elaborated on the model.
According to this model there are three types of consumption: past, present and future.
This decision making is based on an indifference map with negative slope because if he consumes something today it means that he can't consume it in the future and vice versa.