Reification – a key principle in Gestalt thinking is the constructive or generative aspect of perception. The reification principle observes how the visual cortex in the human brain processes the limited visual stimuli and generates a more complex perception than the sensory input.

The image below demonstrates how human visual system performs the reification process. In Figure A – also known as the Kanizsa triangle,​ although no triangle has actually been drawn, the humans perceive a triangle whose boundaries are completed and its surface filled-in.