Optical illusions may seem like playful tricks, but they reveal deep insights into how the human brain works. Our brains rely on shortcuts, contextual clues, and predictions to interpret the world around us. While these processes usually help us navigate daily life, they sometimes create false perceptions.

For instance, the brain often assumes light comes from above, fills in missing edges, and exaggerates contrasts to make sense of incomplete or ambiguous information. This explains why two identical colours may appear different depending on their background, or why lines of equal length look unequal when framed differently.

Illusions such as the Kanizsa triangle or the Müller-Lyer lines highlight how perception departs from physical reality. Scientists explain that the brain is constantly guessing what it sees, using past experiences and environmental patterns as guides.

These “rational mistakes” show that our mind doesn’t passively record reality—it actively constructs it. Optical illusions therefore aren’t just fun puzzles; they’re windows into the remarkable ways the brain processes vision, sometimes bending reality itself.