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Your Brain Is Constantly Searching for Problems to Fix - Tonic

Instead of carefully deciding how threatening a face is compared to all other faces, the brain can just store how threatening it is compared to other faces it has seen recently, or compare it to some average of recently seen faces, or the most and least threatening faces it has seen. This kind of comparison could lead directly to the pattern my research group saw in our experiments, because when threatening faces are rare, new faces would be judged relative to mostly harmless faces. In a sea of mild faces, even slightly threatening faces might seem scary. It turns out that for your brain, relative comparisons often use less energy than absolute measurements.

A little labeling goes a long way: Infants can use a few labeled examples to spark the acquisition of object categories -- ScienceDaily

"These results suggest that semi-supervised learning can be quite powerful. Seeing just two labeled examples jump-starts infants' category learning. Once they've heard a few objects receive the same label, infants can learn the rest on their own, with or without labels," said Alexander LaTourrette, the lead author of the study and a doctoral candidate in cognitive psychology in the Weinberg College of Arts and Sciences at Northwestern. Moreover, the timing of the labeling mattered. If the two labeling episodes came at the end of the learning phase, after infants had already seen the unlabeled objects, they failed to learn the category. This tells us that infants can use semi-supervised learning. They use the power of labeling to learn more from subsequent, unlabeled objects.