Numerical digits influence perceived duration; specifically, higher numerical digit values are perceived to be longer than lower ones that are presented for the same duration of time. To examine the functional relationship between digit value and perceived duration further, three models based on digit value and covered area were tested in two experiments. Unlike previous studies, each experiment utilised the entire digit range that spans from 1 to 9. In both experiments, digit values were presented visually during the target interval of a time reproduction task. Although numerical digits (i.e., Arabic digits) were used in Experiment 1, verbal digits (i.e., number words) were utilised in Experiment 2. In the case of the numerical digits, perceived duration increased as a function of digit value, while the effect of covered area failed to reach statistical significance. For verbal digits, however, the effects of both digit value and covered area were statistically significant. Overall, our findings support the existence of two distinct nontemporal processes that are involved in the modulation of perceived duration: one process that is based on a digit's surface characteristics (i.e., covered area) and another process that is based on the digit's numerical meaning (i.e., digit value).
Keywords: Time perception; nontemporal stimulus magnitude; number words; temporal reproduction.