Yes, ColinsMum is right. According to the Wikipedia article on Theory of Mind, http://en.wikipedia.org/wiki/Theory_of_mind it says, "Most normally-developing children are unable to pass the Sally and Anne test task until around age 4." I've also heard from my son's ABA therapist that typically developing children should be able to pass this test around 4 or 5. The article also mentions that "In one study, 80% of children diagnosed with autism (age range 6.1-16.6 with IQ range 70~108) were unable to pass the test."