My son, 21 months, is being evaluated for autism. I noticed around 16/17 months that his pre verbal communication skills seemed to be lacking (pointing and other gesturing) and his imaginative play is also limited.
His pointing has improved (although he still doesn't use many other gestures like waving) - he will use informative pointing when looking in books, and will also now use imperative pointing (although not always looking back at me), but his pointing to show interest is still a bit patchy. He points at lots of things which he finds interesting, but doesn't often look to see if I am also looking.
Are there other examples of showing joint attention (which I'm not sure that he does)? Yesterday he pulled lots of videos off our shelf and got heartily told off for it. This morning he was kneeling in front of the shelf, pulled one video off and then turned round to see if I was watching with quite a mischievous twinkle in his eyes. Is that joint attention?