Rubber hand illusion shows how easily our brains can be misled.

One of the things that contributed a lot to my eventual deconversion to atheism was learning more about how the human brain works. Many believers will admit that they may not have a rational basis for what they believe, but they know it’s real just the same and I accept those statements as sincere. The reason that I don’t find them convincing, however, is because it’s possible to experience all sorts of things that feel entirely real even when we know for a fact that they are not. It’s possible, for example, to still gain some benefit from a placebo even when you know it’s a placebo.

These days there are all sorts of cool experiments being done that show that the brain can be tricked into thinking something that’s not real is very real even when the evidence that it’s not real is right there in front of its eyes. Experiments like the rubber hand illusion:

The rubber hand illusion is more than a vaguely creepy parlor trick. It’s a window into relationship between our mental and physical self-conception.

During the illusion, a participant’s hand is hidden, and a rubber hand positioned so that it appears as her own. She knows that it’s fake—but when both hands are stroked simultaneously, what’s seen and felt becomes blurred.

Suddenly the rubber hand literally feels like it belongs to her. Consciously she knows it’s not true, but that doesn’t matter. Threaten the fake hand, and people under the illusion’s spell respond as if their own hands were threatened.

Scientists have now shown that the hidden hand’s temperature drops during the illusion: its effects aren’t simply mental, but physical as well, and could even hint at as-yet-unknown processes of disease.

The fact that they can clearly see the hand is fake and not a part of their body doesn’t stop these people from feeling as though it were and reacting accordingly. Their brain overrides what is plain to their eyes and insists that the fake hand is real and something to be protected. Knowing this it becomes very easy to see how people can have experiences that couldn’t possibly have occurred that seem very real to them and which they find very hard to dismiss as a result. Be those experiences sensations of communion with God(s), abductions by aliens, or what have you.