Full Idea
Perhaps the brain doesn't actually have to go to the trouble of "filling in" anything with "construction" - for no one is looking.
Clarification
This refers to filling in things like the blindspot in our visual field
Gist of Idea
Perhaps the brain doesn't 'fill in' gaps in consciousness if no one is looking.
Source
Daniel C. Dennett (Consciousness Explained [1991], 5.4)
Book Reference
Dennett,Daniel C.: 'Consciousness Explained' [Penguin 1993], p.127
A Reaction
This a very nice point, because claims that the mind fills in in various psychological visual tests always has the presupposition of a person (or homunculus?) which is overseeing the visual experiences.