Mind Hacks

Hack #32. Explore Your Defense Hardware

We have special routines that detect things that loom and make us flinch in response.

Typically, the more important something is, the deeper in the brain you find it, the earlier in evolution it arose, and the quicker it can happen.

Avoiding collisions is pretty important, as is closing your eyes or tensing if you can’t avoid the collision. What’s more, you need to do these things to a deadline. It’s no use dodging after you’ve been hit.

Given this, it’s not surprising that we have some specialized neural mechanisms for detecting collisions and that they are plugged directly into motor systems for dodging and defensive behavior.

In Action

The startle reaction is pretty familiar to all of us—you blink, you flinch, maybe your arms or legs twitch as if beginning a motion to protect your vulnerable areas. We’ve all jumped at a loud noise or thrown up our arms as something expands toward us. It’s automatic. I’m not going to suggest any try-it-at-home demonstrations for this hack. Everyone knows the effect, and I don’t want y’all firing things at each other to see whether your defense reactions work.

How It Works

Humans can show response to a collision-course stimulus within 80 ms. ¹ This is far too quick for any sophisticated processing. In fact, it’s even too quick for any processing that combines information across both eyes.

It’s done, instead, using a classic hack—a way of getting good-enough 3D direction and speed information from crude 2D input. ...