If you spend even one day monitoring how often you are able to understand the topic in a conversation by following the speaker's eye gaze, you will come to understand how important it is to monitor eye-gaze--meaning pay attention to what other people are looking at. Here is a fun game that a mother is using to help her son pay attention to her eye gaze. Her son is suppose to move one of his hands out of the way before she "slaps" it and her eye-gaze tells him which hand to move.
The evidence of a great activity between parent and child is pleasure--and they are having sooo much fun. So this is a great game. Secondary, but also important is evidence of learning. I want to mention that we need to play quite a variety of games with children at our clinic before they learn this skill well enough to use it throughout the day. But when they do learn it, it is truly like a light has been switched on. With many children, I think that paying attention to eye-gaze and listening to language is too much information, so most the early games we use involve minimal language. I refer you to Dr. Gutstein's Activity Books to find more games to teach this skill.