Optical illusion: Shades of grey.

What’s the illusion, you ask? Those two vertical lozenge-shapes are the same shade!

Don’t believe me? Good! It’s always best to check things like this out for yourself. One way is to put your finger across the middle, blocking the part where they meet. When you do that, boom! You can see they’re the same shade of grey.

via Phil Plait: Optical illusion: Shades of grey..

I think it’s important to be aware of illusions like this.  It should serve as one of many reminders that our intuitions, outside of every day life, are not to be trusted.  They can betray us.  So, when considering scientific propositions, remember that even if it feels intuitively wrong, evidence should trump that intuition.

6 thoughts on “Optical illusion: Shades of grey.

    1. Well, I would say that in many everyday situations, in situations that we have a great deal of familiarity, our intuitions work just fine. Decisions like choosing what to have for lunch, knowing if what I’m about to say will embarrass a friend, knowing when our car isn’t running quite right, etc. For most of us, intuitions tend to be unreliable when we try to understand the economy, other cultures, or quantum mechanics (unless we’re an economist, anthropologist, or physicist respectively).

      Let me know if that elaboration doesn’t clarify.


      1. That clarifies perfectly – I think I was having a huge mental block likely due to my reading on the unconscious and was equating conscious will and the Self with “every day life” intuitions. From Wilson and Kahneman to Gazzaniga and now Hood … “I” might have to insist on a break before the next book 🙂


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