Key elements of a picture's narrative can be compositionally arranged in a manner that they are not immediately obvious. This results in a slow reveal of the story; a phenomenon known as delay. The prolonging of the viewing process turns engagement with the image into a significant event - delay is about the experience of the viewer who is required to expend some effort, to be rewarded by the surprise of realisation. Delaying tactics include:
1. Spatial reorganisation
The embedding of a key element is achieved through misdirection - pulling away to sequester the important detail instead of stepping in to highlight it; and using geometries under Gestalt perception to lead the eye along a different route.
Referencing a subject which is out-of-frame - its shadow, reflection, or person's reaction to it.
3. Unexpected phenomena
Where something turns out to be other than what it first appears to be, such as a Trompe-l'œil.
The trick to successful delay lies in the provision of adequate clues to bring about realisation.