The perspective box or peepshow is an optical device which enables an artist to create a convincing illusion of interior (or, more rarely, exterior) space. Using a complex perspectival construction, the four inside walls of a wooden box are painted to simulate the space and the scene is then viewed through a carefully positioned eyehole. The eye is deceived into believing that this is really the inside of a room.
The peepshow was popular among Dutch 17th-century artists, reflecting a fascination with perspectival and optical devices. Of the six peepshows which survive from the 17th century the best is that by Samuel van Hoogstraten in the National Gallery. The inside of the box is painted in such a way that when viewed through either of the peep holes, located at each end, it gives the illusion of a three-dimensional interior of a modest Dutch room, sparsely furnished and with views through into other rooms.