Anna, a 6-month-old infant, is being tickled on the tummy by her grandmother. The grandmother repeatedly tickles Anna twice and then pauses for...

Anna, a 6-month-old infant, is being tickled on the tummy by her grandmother. The grandmother repeatedly tickles Anna twice and then pauses for Anna's giggles. With the tickles, Anna's grandmother says, ìBeep, beep.î After a minute or so of this, Anna becomes bored and stops giggling. Anna's grandmother then changes the pattern to three tickles and ìBeep, beep, beep.î Which response to the change in number of tickles is Anna MOST likely to make?

Anna remains bored.

Anna begins to giggle again.

Anna adds two and three and giggles five times.

Anna says, ìWow, three tickles!î