Name this psychological phenomenon?
January 16, 2010 2:16 AM   Subscribe

What's the name of this psychological phenomenon, and can you help me find an illustration of it?

Many years ago I came across an illustration in a book whose name I have long since forgotten. It was an apparently random pattern of lines and shaded areas containing no recognisable image. On the next page, the same random pattern was shown but with the image of a man on a horse picked out in bold within it. The point was that when you turned back to the first illustration, it was then impossible not to see the man on the horse, even though they had been "invisible" before.

I'm sure this is a well known phenomenon and I'm sure it must have a name. Can you tell me what it's called so I can google up the same or a similar illustration? Bonus points if you can point me towards a public domain example that I can use in a presentation.
posted by genesta to Science & Nature (14 answers total) 5 users marked this as a favorite
I think you're looking for Priming.
posted by handee at 3:28 AM on January 16, 2010 [1 favorite]

Are you talking about cognitive/optical illusions?
posted by Houstonian at 3:30 AM on January 16, 2010

Response by poster: Handee - that's getting close, thanks.

Houstonian - it's not an illusion as such. The image is there all the time, you just can't see it till it's pointed out to you. But once it has been, you can't not see it again. (Great link, though!)
posted by genesta at 5:54 AM on January 16, 2010

I think you're talking about a visual phenomenon called "Afterimages". From this page:

"After exposure to strong light in their sensitivity range, photoreceptors of a given type become desensitized. For a few seconds after the light ceases, they will continue to signal less strongly than they otherwise would. Colors observed during that period will appear to lack the color component detected by the desensitized photoreceptors. This effect is responsible for the phenomenon of afterimages, in which the eye may continue to see a bright figure after looking away from it, but in a complementary color."

It's not really a psychological phenomenon like priming (which is increasing the likelihood of identifying something because you identified it before), but I did learn about it in my psych classes as well through similar illustrations.
posted by parkerjackson at 5:55 AM on January 16, 2010

I don't think genesta is talking about after-images - the example given is not one where the pattern has been stored by the retina, but one where knowledge of a pattern's existence affects what you see. It's a cognitive phenomenon. What you're thinking about changes what you perceive.

A converse effect is seen in in this video - where what you don't perceive is influenced by what you're thinking about.
posted by handee at 6:22 AM on January 16, 2010

Best answer: Handee-- yeah, in re-reading the OP, afterimages don't fit all the criterion. It does seem to be some kind of priming, but there must be a specific term for that one phenomenon as priming is very general.

There's always the gestalt phenomena-- like this picture. Is that closer?
posted by parkerjackson at 6:50 AM on January 16, 2010

This article on the famous FedEx logo arrow links to a psychology site on something called "perceptual set theory", which might be it? A Google image search for "perceptual set" seems related.
posted by rollick at 6:56 AM on January 16, 2010 [1 favorite]

Best answer: Here's a link on a related image, from a not super-authoritative source. The author says it's "a small example of what is called one-shot perceptual learning". This scholarly article seems to use the same term to describe the same phenomenon.
posted by ManInSuit at 7:38 AM on January 16, 2010

Best answer: I think parkerjackson has it - it's a one of the facets of Gestalt principles of perception. Is this the image you remember?
posted by donnagirl at 9:20 AM on January 16, 2010

Oh! I missed the part where you asked for examples. Here are a couple that may help:

here, and here
posted by ManInSuit at 9:26 AM on January 16, 2010

Statistical Summary Representations? (scroll down)

Is this your man on a horse?
posted by Alison at 9:34 AM on January 16, 2010

This is a common one although you switch to seeing the illusion not the reality.
posted by w0mbat at 9:52 AM on January 16, 2010

Response by poster: Fantastic! Thanks to all of you, particularly to parkerjackson for gestalt phenomena. And ManInSuit - your first link is exactly the sort of pic I was looking for.
posted by genesta at 11:38 AM on January 16, 2010

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