In the Childish Gambino song "Heartbeat" the bass player is clearly using multiple effects during the higher energy parts. I'm mostly wondering the sort of tremolo effect he uses to make it swell for a split second every time he plays a note instead of having a short and true attack like a clean bass would have.

Here is the link (sorry I can't remember how to embed).

www.youtube.com/watch?v=naESDJI_w_E the part I'm talking about starts around 0:51


"There's no other way to word it." - Ye