Learn from the experience. That's also Memory Gap management. If you cannot go back to meet those people again, you'll have to find their names another way through a friend or something if it's important.
If you want to avoid such a memory gap in the future realise what you did then did not help you remember the name so do something different next time. Make it stronger and create better hooks. One of the things to do is to say their name at least 3 times in the course of conversation with them while calling up what ever feature or method you chose to remember them by. So if it was Bill with a big bow tie. Make sure you create the connection to the bow tie each time you say the name.
And if you were in a situation where the name was said too quickly that you didn't even have a chance to form a memory, there is your Memory Gap. You need to do something collect the name.
One trick is to ask, what was your name again? When they tell you, you say, no your last name. Now you have both names to play with in adding to your memory.
Alex
