Until recently I had assumed that thinking depends on language. If I understand correctly, Ayn Rand took this view, as did many others.
A neuroscientist at MIT named Evelina Fedorenko has spent 15 years researching this, using modern brain-imaging techniques. Her conclusion: language and thought are, in fact, distinct entities that the brain processes separately, and the highest levels of cognition can proceed without an assist from words or linguistic structures.
She co-authored a recent perspective article in Nature and was interviewed in the March issue of Scientific American (starting on page 86). I have read the interview but no other material.
If she is right, this has big implications for epistemology and for understanding the nature of the faculty of reason. If she is wrong, it would help to prove it.
So far I haven't made plans to devote any more of my time to this. But it calls for a further look.