Résumé en anglais

Multiple criteria decision aiding methodologies rely on basic principles concerning the consistency of decision maker's (DM's) preferences. Among these principles, the Third Alternativ Invariance (TAI) principle states that elicited preferences on two alternatives should not be afected by the presence or availability of a third alternative. Empirical statements on cognitive limitations of decision makers tends to contradict this principle. Our work aims at analysing the behavior of DMs when answering binary and ternary choice questions. Results show a violation of the TAI principle. Such results ma be explained by a shift in the reference points considered by decision makers in the binary and ternary choice questions. Implications for preference elicitation techniques in multiple criteria decision aid are discussed.