The Penumbra of Spatial Apprehension, the downstage semi-circle shown here in red, is the area of the performance space that the performers, unless required to do so by a predetermined spatial choreography, tend to avoid.

When performers enter this penumbra, they tend to face upstage if vertical; or keep their pelvises close to the ground if facing downstage; or move through the penumbra with a trajectory parallel with the front of the stage.

Experience and the likelihood of entering the penumbra do not have a direct relationship.