learning causal connections

"Correlation does not imply causality." Makes sense, right? Well, your brain doesn't think so.

Imagine that there are a bunch of neurons (nerve cells that process information in the brain), labeled A,B,C, and so on, and that there are connections between them. If neuron A emits a "spike" of activity, and then (shortly afterwards), neuron B spikes, the connection from A->B is strengthened, and the reverse connection (from B->A) is weakened.

What does that mean? Well, the next time neuron A spikes, it is more likely that it will cause B to spike (because the A->B connection is strengthened), but the next time B spikes, it is less likely that it will cause A to spike. So your brain is learning the causal structure of the world ("A causes B"), in some sense. And, as explained above, the "signal" that it uses to find this structure is the temporal correlation between activities; which one comes first.

 This effect is called "spike timing dependent plasticity" (STDP) and it remains one of the most significant discoveries in neuroscience.

Maybe that's why people are so quick to assume causality when they see correlations. Could it be that we are hard-wired to make logical fallacies? I dunno, but I sure would like to find out.