Feature Reduction

(looking at baby/toddler photos a year apart) "How does he look so different and yet so the same at the same time?"

"Just in case that was non-rhetorical, the answer is that your brain evolved to be good at factorizing overall appearance into orthogonal 'personal appearance' and 'age appearance' dimensions that can be tracked separately, just as [x, y] = [1, 2] and [4, 2] are so different with respect to x, and yet so the same with respect to y, at the same time."