The correct answer is perceptual salience
The state or quality by which it stands out from its neighbors. Boss detection is considered a key attention mechanism that facilitates learning and survival, allowing organisms to focus their limited perceptual and cognitive resources on the most relevant subset of available sensory data.
Overhang usually arises from contrasts between items and their neighborhood, such as a red dot surrounded by white dots, a message answering machine flicker or loud noise in another quiet environment. Bump detection is often studied in the context of the visual system, but similar mechanisms operate in other sensory systems. What is salient can be influenced by training: for example, for humans, particular letters can become salient by training.