The aim of this study was to develop Information-Processing Style Inventory (IPSI), which measured individual differences in rational and intuitive thinking (Pacini & Epstein, 1999). In Study 1 (N=290), a confirmatory factor analysis was performed to examine the factorial validity of 38-item IPSI. Results confirmed that IPSI consisted of two factors; rationality and intuition. IPSI also had acceptable internal consistency and test-retest reliability. Results of correlational analyses with other scales (ambiguity tolerance, theory orientation, self-esteem, and social desirability) showed high discriminant and convergent validity for IPSI. In Study 2 (N=237), IPSI scores and probability-reasoning performance were examined to assess its construct validity. Results indicated that both rationality and intuition explained frequencies of corresponding reasoning error. In Study 2, a 24-item short version of IPSI was also developed and its reliability and validity were examined.
Key words: information-processing mode, individual differences, rational thinking, intuitive thinking, two factors