The book 'Beyond Bullet Points' uses a great analogy to explain how our different memories work. It uses the eye of a needle to demonstrate how information gets from our sensory memory to our long term memory.
Think about information going through an eye of a needle. It is your job when designing learning to make the thread thin and smooth enough to be pulled through the eye. Your audience cannot make thick wool narrow enough while you are talking. Their working memory will become overloaded (often called cognitive overload). You also don't want them undoing knots in the thread (or head). Keep learning in chunks of three or four things to help people move it around in their minds.
If you want to find out more about Presenting a Memorable Message or you can join the CIPD South East Scotland Branch Meeting on 20 February (£10 for non-members) or Train in the Grain of the Brain in October. I will not be delivering this event alone, Neil Slorance, a cartoonist will be joining me to draw brain friendly learning.