Follow-through
Also said as Overlapping action, Secondary motion
Loose parts keep moving after the main body stops: hair, capes, a tail, a scarf. They arrive late and settle slowly.
The eye reads the lag as physics and mass, and it costs almost nothing, since a rope simulation is cheap. It is one of the quickest ways to make a stiff character seem alive.
Say it
“Give the character a scarf on a rope simulation: pinned at the neck, dragged by run speed, settling for half a second after they stop.”
Where you’ve seen it
The scarf in Journey trails behind the traveller, and its length also shows how far you can fly. Few details in games do two jobs so neatly.
Not to be confused with squash and stretch
Squash and stretch changes the body's own shape. Follow-through is what the parts attached to it do afterwards.