Divide group into pairs and have them sit or stand facing each other. Then ask them to observe their partner focusing on details, clothing, jewelry and appearance, etc. After a few minutes observing they both turn their backs to each other and make three changes in personal appearance (change hair, move a ring to a different finger, unbutton a sleeve etc.) Partners then turn and face each other again trying to identify the changes.
Repeat this process with different partners and different numbers of changes with more or less.