Recent comparisons help the brain work quickly but cause severe problems

A little bit more detail on that story about why we never think things are getting any better.

Why do people expand what they call threatening when threats become rare? Research from cognitive psychology and neuroscience suggests that this kind of behaviour is a consequence of the basic way that our brains process information – we are constantly comparing what is in front of us to its recent context.

Instead of carefully deciding how threatening a face is compared to all other faces, for example, the brain analyses how threatening it is compared to other faces it has seen recently – or compares it to some average of recently seen faces, or to 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: 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. Just think about how it’s easier to remember which of your cousins is the tallest than exactly how tall each cousin is. Human brains have likely evolved to use relative comparisons in many situations because these comparisons often provide enough information to safely navigate our environments and make decisions, all while expending as little effort as possible.
http://www.bbc.com/future/story/20180710-why-the-brain-always-finds-new-problems-and-threats