Inclusive and exclusive modes of thinking: Studies of prediction, preference, and social perception during parliamentary elections

The 1999 Israeli multi-party parliamentary election was used for studying the effects of inclusive and exclusive modes of thinking. In three experiments, we tested a theoretical framework whose major elements are the justification process, a distinction between middling and clearcut options, and the use of inclusion and exclusion threshold criteria. In Studies 1-2, respondents were asked to predict either of which parties would win seats in the parliament (inclusion) or which parties would fail to win seats in the parliament (exclusion). In Study 2, respondents were also asked to use inclusive or exclusive modes to indicate their preferences and in Study 3, they were asked to make either inclusive or exclusive judgments about the platforms of two extreme political parties. We found consistent discrepancies between the outcomes of inclusion and exclusion processes, such that choice sets generated in exclusion were larger than those generated in inclusion. A second major finding was the option effect, namely, the discrepancies between the two modes of thinking were larger for middling than for clearcut options. The third main finding was an expertise effect: the less knowledgeable respondents exhibited greater discrepancies than did the more knowledgeable ones. Our theoretical framework accounts for the inclusion-exclusion discrepancy, the option effect, and the expertise effect. We discuss the implications of these findings for judgment and choice in social settings and also for the understanding of question-form effects in opinion surveys—in particular, the allow-forbid effect.