... the brain is a creativity machine, which obtains incomplete information from the outside world and completes it. We can see this with illusions and ambiguous figures that trick our brain into thinking that we see things that are not there. In this sense, a task of figurative painting is to convince the beholder that an illusion is true.
It's been said (via Scott McCloud) that people who start reading comics when they are young train their brains to recognize artistic patterns a little differently than people who don't. Not to say that comics are the only way to do this, but that's one example of an effect that can be manifested multiple ways. The more we train ourselves to suspend disbelief and allow the imagination to do its own thing in different ways, the easier it becomes to enter the world someone else has created.
Too much of a good thing is also possible, though. Consider the cranks and paranoids who see conspiratorial behavior in every innocuous action or random coincidence. Their pattern recognition systems have been turned up to 11 and gotten stuck there. But I've long suspected that happens not because of their pattern recognition faculties alone, but because said faculties have been hijacked by the fear centers and the fight-or-flight parts of the brain.
Suspension of disbelief is something we train ourselves to do. Most of the time, we're not even aware that we're doing it. As kids, we practice the Tinkerbell Trick in a totally natural way — we do it because at that age, some part of us needs to do it. It's how our brains attempt to prime themselves to deal with the future complexity of life, I think.
A brain that forgets how to dream is a damaged one. That might explain why, at some of the worst times in my life, I sometimes spent months without having a single dream whenever I slept. To dream under such dour circumstances seemed futile. It frightened me that I might have to teach myself to dream again.
But at the same time, I don't believe mere suspension of disbelief alone is what matters. It primes the pump, but one has to keep pumping. We may not need to teach ourselves to dream if we've been doing it all along, but we do need to teach ourselves how that power can be harnessed to the whole of our lives. I'm not sure a specific instruction manual exists for this, though.