This demonstration uses one of the most famous human faces, the portrait of Mona Lisa, La Gioconda, by Leonardo da Vinci. Usually, we have a very accurate and stable representation of the exact configuration of such a familiar face. Typically, we are able to rapidly recognise even subtle configural changes. However, here we show that an exposure to specific alterations performed on a familiar face substantially reduces this ability even over a time period as long as 80 min. This demonstration illustrates the flexibility of the perceptual system and adaptation to new information.