Visual illusion example (IMAGE) Universitat Pompeu Fabra - Barcelona Caption In all three cases, the Sagrada Familia is the same colour but looks different due to the surrounding colours. This is a visual illusion. Credit - Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.