Previous research has demonstrated that number size can influence time perception, with larger numbers leading to longer subjective duration estimates, a phenomenon known as the numerical effect on time perception. This study investigated how the combination of numbers and conceptual magnitudes (both familiar and unfamiliar) affects time perception. In Experiment 1, numbers (1, 2, 8, 9) were paired with low-familiarity length magnitudes (e.g., decimeter, millimeter), while Experiment 2 paired the same numbers with high-familiarity length magnitudes (e.g., kilometer, centimeter). Results from Experiment 1 indicated that, under low-familiarity conditions, conceptual magnitude did not modulate the numerical effect on time perception. In contrast, Experiment 2 demonstrated that, under high-familiarity conditions, the numerical effect persisted when paired with large conceptual magnitudes but disappeared when paired with small ones. These findings suggest that the interaction between number and conceptual magnitude influences time perception, with familiarity playing a crucial moderating role, thus supporting the integrated magnitude system theory.
