In How We Learn: The Surprising Truth About When, Where, and Why It Happens by Benedict Carey, he reminds us:
The brain is not like a muscle, at least not in any straightforward sense. It is something else altogether, sensitive to mood, to timing, to circadian rhythms, as well as to location, environment. It registers far more than we’re conscious of and often adds previously unnoticed details when revisiting a memory or learned fact.
It works hard at night, during sleep, searching for hidden links and deeper significance in the day’s event. It has a strong preference for meaning over randomness, and it finds nonsense offensive.
It doesn’t take orders so well, either, as we all know –forgetting precious facts needed for an exam while somehow remembering entire scenes from The Godfather or the lineup of the 1986 Boston Red Sox.
If the brain is learning machine, then it’s an eccentric one. And it performs best when its quirks are exploited.
Carey’s book makes no mention of absolutes in the introduction. He writes:
Cognitive science …clarifies how remembering, forgetting, and learning are related.