'...the activities gradually expand. They gradually expand in duration, they gradually expand in content and they gradually expand in sophistication and complexity - simply through the main engine-room of that repetition'. (Dave Hewett, The Intensive Interaction Handbook, p.149)
I have really seen this taking place with the relatively recent game of M. pointing to my eyes, nose and mouth in turn for me to label. I wrote about the first time it happened here, and it was a really amazing sense of connection and interest in another person's face (which is not something she would normally look at for a sustained length of time). Then there was a bit of a further development where she spontaneously added the label 'leg' and pointed to my leg (see here). The next time the game occured I took a risk and started alternating between labelling 'Mummy's eyes' and 'M.'s eyes' and she was comfortable with that (see here). Yesterday the game occured again, with M. adding another variation of beginning with her own face instead of mine and also adding in 'head' before 'eyes', 'nose' and 'mouth'.
After we had played the game a few times (with her variations) I decided to take a risk with a little bit of playful sabotage, and when she pointed to her mouth I said 'arm'. She didn't show any response to this but terminated the game shortly afterwards... Clearly variations on this game are on her terms! :)