Perceiving numbers alters time perception

The representation of time, space and numbers are strictly linked in the primate’s cognitive system. Herewe showthat merely looking at number symbols biases a temporal judgment on their duration dependingupon the number’s magnitude. In a first experiment, a group of healthy subjects was submitted to a timeestimation task, requiring to judge whether the duration of a test stimulus was longer or shorter thanthat of a previous reference fixed stimulus (digit 5; duration 300 ms). Test stimuli were the digits 1, 5and 9 ranging between 250 and 350 ms. The main results showed that temporal perception was biasedaccording to the magnitude expressed by the digit: low digits (i.e. 1) leading to underestimation and highdigits (i.e. 9) an overestimation of perceived duration. Control experiments showed that this result wasconsistent whatever digits were tested but not when letters of the alphabet were used. These findingsargue for a functional interaction between time and numbers in the cognitive system.