The aims of this study were to examine with a Japanese sample the idea that the expectation of slack in the future is larger for time than for money and to examine the relationship between this expectation and optimism as a personality trait. The results showed that Japanese participants estimated slack with regard to both time and money, and it was larger with regard to time than to money, consistent with research done on American samples. Inconsistent with our hypothesis, however, the expectation of slack did not correlate with optimism. The low correlation between the estimated degrees of slack between that with regard to time and that with regard to money suggests that there is no consistent tendency across different resources.
