What Are The 4 Clues To Listening Properly?

I never heard of any four clues. Too listen to someone fully is just being there with them and giving them your complete attention.  I can tell if someone is not listening fully by looking at them. Sometimes a person might hesitate and look at me to see if I am listening and I just raise my eyebrows a little or a slight smile which tells the person, yes I am still listening.  Now, the person who is suppose to be listening might be facing you, but is thinking of something else while you are talking. This is usually apparent by a blank stare.  So, the person needs to first get the other persons complete attention before talking and check now and then to see if he is still connected.

Look directly at the person, pay attention, respond when asked something, and don't interrupt.