Quoted from http://www.babycenter.com :
“If stand-up comedians gave shows for babies, yours would be starting to get the jokes. If she hasn’t already, she’ll soon laugh at funny expressions and try to make you laugh, too. She’s showing her emotional side in other areas, as well — a sharp contrast to when she was a newborn and didn’t have all the physical and cognitive skills to let you know how she felt. At this age, she’ll demonstrate her strong attachment to you by raising her arms when she wants you to pick her up, crying when you leave the room, and giving you hugs and kisses”