There are several signs that a person is listening:
- Not fidgeting
- Maintaining eye contact
- Nodding
- Leaning forward
- Copying posture
These are self-explanatory, but an evil audience is known for having it's mentally deficient, so I will explain these further.
Fidgeting is a sign of boredom, so the less one wiggles, plays with something, or otherwise interacts with things other than the person being ignored, the better. Eye Contact means that you look at the person's face more often than not. Nodding is a nearly universal sign of agreement, and is taken as encouragement to continue. Note well that nodding too much can be worse than nodding too little. Leaning Forward is easiest to display when sitting down, but can be done while standing. Like nodding, it is best not to lean forward too far, otherwise you look weird.
Copying Posture gets its own paragraph, because it is one of the few that is least likely to be obvious. To let someone know that you agree with them, you should begin to mirror their body movements or limb positions. If they slouch, you slouch. If they move their hands, move yours in the same way. Do not magnify their posture or movement, merely copy it.
These basic tricks will have others believing that you are listening to them and want to hear more. But be wary! Sometimes you will run into someone who is a little too keen. These members will be able to spot someone who is truly not paying attention, but you have one last trick up your evil, grubby sleeves: Echoic Memory.
Echoic memory is a type of sensory memory. Like all sensory memory, it is perfect but short lived. For a period of about four seconds after hearing something, you will have perfect recall of that thing you heard. This is why children and teenagers are able to repeat what their mother's have commanded them to do, and then forget about it the next second. This insidious type of memory can be used to your advantage because it allows you to repeat back to the person what they have said in the last four seconds. But make sure to do it in your own words, because that is also a sign of paying attention.
For more information, I have provided a list of websites that list more ways of paying attention. Make certain that you only use the aspects that don't actually require you to pay attention!