Explaining how preferences change across joint versus separate evaluation

This paper examines how preferences for outcomes change across joint versus separate evaluation of alternatives. In joint evaluation, two (or more) op tions are presented and evaluated simultaneously. In separate evaluation, e ach option is presented and evaluated separately. We review a growing body of evidence demonstrating this type of preference shift and discuss how it is different from existing biases and preference reversals documented in th e literature. We then review and integrate three competing explanations for this type of preferential inconsistency. (C) 1999 Elsevier Science B.V. Al l rights reserved. JEL classification: Experimental; Theoretical treatment [9130]; Organizational behavior [2500].