 Although SEU continues to enjoy widespread support as a normative model of choice behaviour (though see  Section 5  below), it is no longer generally taken to be descriptively adequate. A number of substantial deviations from its predictions were noted as early as the 1950s and early 1960s by the likes of Allais (1953a,b) and Ellsberg (1961) and further investigated in the 1970s. These observations led to the development of alternative models whose own predictive consequences have become the focus of extensive testing in the past three decades or  so.[3] 