Attentive body language
When you are in conversation or otherwise attending to what others are saying or doing, you body sends signals to the other person as to how interested you really are. Attentive body language sends a strong signal of real and deep interest that is both flattering and likely to result in reciprocal attention.
It was said that if you met with the English 19th century politician William Gladstone, you would come away thinking he was the most intelligent and witty person in the country. If, however, you met his peer Benjamin Disraeli, then you would come away thinking that you were the most intelligent and witty person. Disraeli, it would seem, was somewhat more skilled at paying attention.
Listening
A person who is attentive is first of all listening. This can be of varying intensity though attentive listening is deep and interested.
Ignoring distractions
There are many competing stimuli that demand our attention. If a person ignores distraction, from phone calls to other people interrupting, then they send strong and flattering 'I am interested in you' signals.
Stillness
Body movement often betrays distracting thoughts and feelings. When the listener is largely still, the implication is of forgetting everything else except the other person, with not even internal dialogue being allowed to distract.
Leaning forward
When I am interested in you and what you have to say I will likely lean slightly towards you, perhaps better to hear everything you have to say.
Tilted head
An attentive head may be tilted slightly forward. It also may show curiosity when tilted to the side (although this may also indicate uncertainty).
Gaze
An attentive person looks at the other person without taking their gaze away. They will likely blink less, almost for fear of missing something.
Furrowed brow
Concentration may also be shown in the forehead as the eyebrows are brought together as the listener seeks to hear and understand the other person.
Wanting more
An attentive person seeks not just to hear but to be ready to listen to everything the other person has to say.
Patience
When you want to hear more from the other person you are patient, listening until they have finished speaking and not butting in with your views. Even when you have something to say or when they pause, you still patiently seek a full understanding of them and give them space in which to complete what they have to say.
Open body
Open body language shows that you are not feeling defensive and are mentally open to what they have to say (and hence not closed to their thoughts).
Slow nodding
Nodding shows agreement and also encourages the other person to keep talking. Fast nodding may show impatience, whilst a slower nod indicates understanding and approval.
Interest noises
Little noises such as 'uh huh' and 'mmm' show that you are interested, understand and want to hear more. They thus encourage the other person to keep talking.
Reflecting
When you reflect the other person back to them they feel affirmed and that you are aligned with them. Reflecting activities range from matching body language to paraphrasing what they say.