The author stresses the importance of studying the role of expectation in perception, especially with regard to individual differences and their determinants. A specific framework is outlined as a heuristic tool in such studies. Subjects' perception reports were studied in situations with a discrepancy between ‘focal stimulus’ and built‐in expectation. ‘Summary distortion scores’ were derived, expressing the individual's tendency to choose a pro‐expectational report rather than a pro‐stimulus report. Individual differences in this respect were then compared with data on more general cognitive characteristics and other tendencies of