The Truth Behind Visual Illusions

An interesting question to ask is what happens when our brain’s visual system encounters certain visual illusions? Or more precisely, what exactly happens to our visual perception skills?

Take for example the famous Rubin vase-face image in which two facial profiles and a vase are depicted in a single black and white drawing.

Although the two profiles and the vase can be seen in the drawing, our visual processing skills cannot perceive both figures simultaneously. In fact, at any given moment we are only able to see either the facial profiles or the vase, but not both.

The problem in this case stems from the fact that the outline of the vase is shared by the two profiles, and vice versa. This causes difficulty in our visual processing capabilities to decide which figure to focus on - the two profiles or the vase - and which is designated as background and to be ignored.

Scientists have broken down visual illusions into three distinct categories: literal, physiological and cognitive illusions.