You have full access to this open access article. Recent evidence suggests that interval timing the judgment of durations lasting from approximately ms. We used surface electromyography EMG and motion capture technology to explore the emergence of this coupling in 4-, 6-, and 8-month-olds.
We engaged infants in an active and socially relevant arm-raising task with seven cycles and response period. In one condition, cycles were slow every 4 s ; in another, they were fast every 2 s.
In the slow condition, we found evidence of time-locked sub-threshold EMG activity even in the absence of any observed overt motor responses at all three ages. This study shows that EMGs can be a more sensitive measure of interval timing in early development than overt behavior.
Interval timing concerns our ability to judge the length of events taking from a few seconds up to a few minutes Buhusi and Meck ; Grondin ; Zakay and Block It is different from precision timing occurring on a scale of less than ms , which is involved in online motor control, and from long-term time perception occurring on a scale of hours involved in culturally specific notions of time.
It is an ability that we share with many other species, and which appears to be present from early in human development. Indeed, over the last 15 years, substantial evidence using heart-rate measures Colombo and Richman , ERP measures Brannon et al. But where does this ability come from? Our answer to this question starts from the view that action structures the sensory world.
