Working memory affects motor, but not perceptual timing

Whether different timing tasks utilize the same brain processes is still debated. To approach this question, we investigated how working memory affects two different timing tasks: time reproduction and time discrimination. We found that delay interval led to an overestimation in the reproduction task but did not lead to any bias in the perception of time in the time discrimination task. Delay intervals affected perception of time when subjects had to actively reproduce the perceived interval, but not when subjects were going to just recall the content of the working memory. In a subsequent Bayesian modeling, we showed that in the reproduction task, subject updated their measurement of the stimulus on the current trial(likelihood), based on the delay interval, rather than changes in motor system, or updating prior based on the delay interval. Our findings suggest that brain processes that are involved in time reproduction and discrimination are not completely overlapped, and delay interval in working memory task leads to changes in updating the likelihood.