headshot of George Dinwiddie with books he's written

iDIA Computing Newsletter

April 2024

Don't Believe Your Lying Eyes

Our senses are not reliable. We see mirages, optical illusions. I covered some of those in my January 2024 newsletter, "The Brain is Amazing." I've recently been reading about some other ways that our sensory perceptions are not reliable.

What color are these strawberries? (image of a photo of strawberries with all of the red pixels replaced with gray ones.) Akiyoshi Kitaoka, a psychologist from Ritsumeikan University in Japan, removed all of the red pixels in this photo, replacing them with gray. Your brain automatically shifts the perceived wavelengths on the assumption that there's too much blue in the photo and assumes that indicates it was photographed under cool lighting. It's trying to show you how it would look under white light.

Another interesting perception issue is the appearance of time. When we're looking at something that is moving, we're always working a little bit into the future. It turns out that the internal processing of sensory information, especially visual, is a bit slow, so the brain anticipates where the object will be at the end of that processing based on where it was and how fast it appeared to be moving.

If it didn't, then we would have a hard time hitting or catching something that's moving. It adjusts our perception of reality so that when it's finished processing, the object is likely where we perceive it to be. When compared with something that is not moving, say an object that flashes momentarily in view, the effect is startling. You can observe this flash-lag effect and see for yourself.

(Image of a cross of text that reads 12 13 14 from top to bottom and A B C from left to right. The font of the 13 easily looks like a capital B because the digits are close together.) What is in the middle of the image to the left?

If you started with reading across, you likely saw a 'B', but if you were reading down, you interpreted it as "13." Context matters. Some of that context is in the here and now, and some of it is in our prior history.

Now imagine this: You're at a potluck party and there's a big bowl of tortilla chips and a bowl of hot sauce next to it. You don't like spicy food, but you take a big dip of guacamole from the bowl next to it.

Only it's not guacamole. It's wasabi sauce for the sushi rolls on the other side of the table. Ouch!

Green stuff next to tortilla chips and salsa? What else could it be but guacamole. Your prior history and the context around it made you confidently wrong!

/signed/ George

P.S. Please help me out.

I'd love to hear your story of a time you mis-perceived something in the world around you. It could be through any of your senses, not just vision.

And if you'd like to talk further about this topic, you could schedule a Zoom Session with me to talk about it.

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Or you can also simply reply to this email or send an email to newsletter@idiacomputing.com to continue the conversation. There's a person, not a bot, on this end. I'd really love to hear from you.