Two studies provide evidence for the reliability and validity of a new self-report measure of individual differences in intuitive-experiential and analytical-rational thinking based on cognitive-experiential self-theory (CEST). The Rational-Experiential Inventory (REI) was constructed to measure the 2 independent processing modes with a modified Need for Cognition Scale (NFC, J.T. Cacioppo & R.E. Petty, 1982) and a new scale, Faith in Intuition (FI). In Study 1, a factor analysis yielded 2 orthogonal factors corresponding to NFC and FI. Although heuristic processing was determined primarily by FI, NFC also contributed to heuristic responding, in line with CEST. The relation of FI and NFC to coping ability also was examined. In Study 2, the factor structure of the REI was replicated (N = 973). NFC and FI were differentially related to measures of personality, adjustment, achievement, and interpersonal relations.

When offered an opportunity to win $1 on every "win" trial in which they drew a red jelly bean, subjects frequently elected to draw from a bowl that contained a greater absolute number, but a smaller proportion, of red beans (e.g., 7 in 100) than from a bowl with fewer red beans but better odds (e.g., 1 in 10). Subjects reported that although they knew the probabilities were against them, they felt they had a better chance when there were more red beans. Similar, but less extreme results were obtained on "lose" trials, where drawing a red bean meant losing $1. These results were predicted from the concretive and experiential principles of cognitive-experiential self-theory. Nonoptimal choices in the laboratory were significantly correlated with heuristic responses to relevant vignettes and with self-reported gambling in real life.

A well-substantiated, surprising finding is that people judge the occurrence of an event of low probability as less likely when its probability is represented by a ratio of smaller (e.g., I in 20) than of larger (e.g., 10 in 200) numbers. The results of three experiments demonstrated that the phenomenon is broadly general and occurs as readily in pre-as in post outcome judgments. These results support an interpretation in terms of subjective probability, as suggested by the principles of cognitive-experiential self theory, but not an interpretation in terms of imagining counter-factual alternatives, as proposed by norm theory.

Results from four experiments (N = 548) support the hypothesis from cognitive-experiential self-theory (CEST) that the resistance of the notorious Linda conjunction problem to solution can be attributed primarily to its simultaneously concrete and unnatural context. The experiments demonstrated that the influence of other variables, such as problem order, event likelihood, within-versus between-protagonist context, and statistical sophistication, although important, cannot account for the robust influence of the combination of the concrete-abstract and natural-unnatural dimensions. The implications of the demonstration that virtually everyone has intuitive knowledge of the conjunction rule are discussed, in addition to cuing effects, narrative processing, and methodological issues that have produced serious distortions in the interpretation of previous research.

Participants who adopted an intuitive-experiential but not an analytical-rational mode of information processing reproduced the usual finding for the Linda conjunction problem of a preference for a heuristic, representativeness over a statistical, conjunction-rule solution. Many who knew and thought of the conjunction rule (the absence of which previously were considered the major reasons for the prevalence of representativeness solutions) preferred a representativeness solution. The widely held belief that people prefer the outcome of their rational more than their intuitive processing when both are equally accessible is of limited generality. The preference by many who know the conjunction rule for a heuristic, representativeness solution can account for both the very high rate of conjunction errors to the Linda problem and their resistance to elimination by training. A finding of a surprisingly strong priming effect suggests that once people engage in a processing mode, it tends to be self-maintaining.