How concentrated is access concentration and how would one recognise it?

A meditation teacher I once had said that access concentration (the stage before the jhanas) is the same level of concentration that one has when reading a good book or when fully engaged in conversation. However when I've read about it in other places it makes it seem like it is a more special level of concentration, perhaps one that you wouldn't ordinarily experience in your day to day life. Which point of view is more correct? How concentrated is access concentration and how would one recognise it?