As in, you've never heard of it and suspect they've just made it up, or you're aware of the concept but have an unorthodox opinion about it? It's a very pervasi

As in, you've never heard of it and suspect they've just made it up, or you're aware of the concept but have an unorthodox opinion about it? It's a very pervasive concept among UX people. If the former, try googling "learnability vs usability" or somesuch?