example: baby learns to eat by himself, artifacts: mom, the word, "ah", mom shows an open mouth, mom demonstrating how she eats, spoon, bowl, rice, chewing, baby's right hand, holding the spoon, putting the rice to his mouth, mom saying "good boy". Social ----- psychological (baby eats by himself thinking about mom saying "good boy" and smile") --- baby laughs at other baby who cannot eat on his own.