Sitting with support is normally seen in a 5-month­old infant. Stranger anxiety (fear of unfamiliar people) does not appear until approximately 7 months of age. A pincer grasp (using thumb and forefinger) appears at approximately 9 months of age, whereas object permanence (the ability to maintain a mental represen­tation of an object although it can no longer be seen) occurs between 12 and 18 months of age. Using mean­ingful words is not commonly present until at least 12 months of age.