I think that many people agree that the "tests" that were conducted were not really tesing intelligence. Many say that it is more a ranking of "trainability" but I don't think that is even a very good word.
In my experience basenjis catch on pretty quickly but get bored easily if things are repeated over and over. Basenjis are great problem solvers, learning all sorts of things we would prefer them not to, like opening the refrigerator, opening the kitchen cabinets, etc.
I don't remember what issue of The Basenji magazine it was in but I remember several years back an article about reasearchers who studied several breeds of dogs to see how quickly they would learn a maze and be able to reach the finish. The comments about basenjis were something like, The basenjis were the fastest through the maze on the first day but seemed to connect finishing the maze with being returned the crate and seemed to resent the researchers and avoided finishing the maze.