People hear and forget. People hear and misunderstand.
It's not merely lack of attentiveness that causes listeners to forget or mis-remember what was said. It is also their lack of the particular context in which to think about and fit what was said.
By context, I mean the fabric of ideas, facts, terms and meanings surrounding the information we listen to. Another term for context could be "background." For example, what is the listener's background of Latin American history, or alternative medicine, or economics? Or, of more homespun backgrounds such as overhauling car engines, or canning cling peaches?
We have all had the experience of listening to a topic for which we had little or no background. Such was my experience earlier this year when listening to a guide describe aspects of Mayan religion. Although I understood the general sense of what I heard, I don't remember much because I had no background into which to fit what I was hearing. And, although I was interested in the subject, what I heard didn't "stick." Names of Mayan historical figures didn't stick because I had no background in Mayan language and its pronunciation.
This experience of not being able to remember what was said to us is common. For example, when we are listening to specialists who share their expertise when we know little about the topic. Many patients leave a physician's office mystified by what was explained to them - unless the physician converses in everyday, non-technical language and perhaps even draws them a picture to explain.
As some readers will recall, Velcro was created in the early 1950s by a Swiss inventor, George de Mestral. While on a hike, M. Mestral's pants and his dog's coat had acquired a lot of burrs-plant seed-sacs that cling to animal fur in order to be carried to new planting ground. Instead of merely pulling them off, instead our creative inventor examined one burr under his microscope. There he saw all the small hooks that enabled the burr to cling so tightly to the fabric of his pants. Nature's hooks on the burr would cling to some kind of weave, mesh, or fabric. M. Mestral decided then he would design such a fastener that copied this principle, and to call it Velcro, a combination of the word velour (a velvet-like fabric) and crochet (a small hook).
The point is that without a "fabric of knowledge" about a subject, the ideas you listen to will not "hook" and you will quickly forget them. However, when you have such a fabric, not only can the related ideas "hook," but you will also have mental frameworks in order to think about those new ideas. And, as cognitive science has demonstrated with experiments, people remember what they think about.
What can a listener do in this regard? The main thing is to "increase your contexts." This can be done in specific topic areas with a modest amount of self-study. For example, by reading up on a subject in one of the "for Dummies" or "Complete Idiot's Guide" books. Together, these series offer more than 700 topic areas, from architecture, chemistry, France, and accounting to geography, Eastern philosophy, and weather. Do you know you will you be meeting or socializing with people from Indonesia, or with a group of landscape architects? The two most common questions asked of strangers we meet are "Where are you from?" and "What do you do?" In a few hours of background reading you can acquire a context to enable "Velcro listening." You'll be able to ask intelligent questions, think about, and remember what you hear. (No time to read? Many of these materials are available in audio-books you can listen to as you drive.)
(For current affairs contexts, I like the new "The Week" magazine and any good national daily newspaper I can read online, such as the Washington Post or New York Times. These provide the knowledge fabric for me to better understand and remember what I hear people say.)
Just as we may need a few dozen words of French to order dinner in Lyons, we usually need a few twists and braids of idea-fabric to catch hold of new or different ideas. A broad, liberal arts education is very helpful in this regard, but it's not the only way to create context. As Ben Franklin's life demonstrated, we can educate ourselves if we have the willingness to do so. And then we can converse with philosophers and diplomats, tradesmen and peasants, and learn from them all.