Well, it just seems unlikely that psychology will produce significant insights here, because it mostly just looks at how the brain behaves. While this can be insightful, I doubt that it will explain intelligence in the end, because this happens a layer below. That's precisely what neuroscience covers. The other approach (just thinking about the problem and trying to to build a AI from first principles) is CS.
So I would expect strong AI from CS, possibly with a paradigm shift caused by an advance in neuroscience.
Those aren't broad definitions at all! Quick question though, what is "acting", what is "thinking", what is "rational"? Your definition of intelligence practically includes the term in its definition(s).
I like the acting human approach (Turing) because it can be stated more precisely. One test is the classic Turing test -- fool a human judge.
Another line for acting human would be the ability to self direct learning in a variety of situations in which a reasonably intelligent human can learn. That means a single algorithmic framework that can learn go, navigate a maze, solve Sudoku, carry on a conversation and decide which of those things to do at any given time. The key is that the go playing skill would need to be acquired without explicitly programming for go.
I believe a lot of our intelligence is the ability to perform solved AI problems given the situation. The key is combining those skills (whether as a single algorithm or a variety of algorithms with an arbiter) and the ability to intelligently direct focus. That's why most researchers aren't confusing alphago with general intelligence. It can play go - period.
AI has some good definitions as far as intelligence is concerned. Perhaps you are worried about consciousness or something, but this is not needed for a definition of what intelligence means.
So I would expect strong AI from CS, possibly with a paradigm shift caused by an advance in neuroscience.