Activation and long-term memory
One characteristic of knowledge which at first sight seems unrelated to its network structure is that some bits of knowledge are more accessible than others.
Suppose you're a typical Brit and I ask you what the capital of France is. You would probably ‘know the answer’ – more precisely, recall the answer – immediately; but what about Finland or Serbia? Given time, you could probably find these too, which is why we can't say that you don't know them or that you know them less well.
Accessibility and frequency
The point is that even if your network includes a ‘capital’ link for each of these countries, this knowledge is easier to find and use in the case of France than in the other two cases. And of course, if I was to ask someone who lived in Finland or Serbia, the relative difficulties would change in favour of their own country.
Why? Because memory is influenced not only qualitatively but also quantitatively by experience. Our theory must explain not only what it means to know that Paris is the capital of France, but also what it means for this fact to be relatively ACCESSIBLE or inaccessible.
Psychologists have done a great deal of research on the various things that influence our ability to recall information, and one common theme is that this ability varies in degree according to the nature of our experience of the thing being recalled.