August 1, 2011

Neil Illusions

Forty years ago, in the April 1971 issue of New Scientist magazine, a new type of optical illusion was described: Neil Illusions, named for the man who discovered them, Allan Neil, of the Institute of Behavioral Research at Texas Christian University.

Here’s how Allan Neil described this new category of illusions in the article:

These new illusions, in sharp contrast to those of the 19th century, do not violate the invariance of parity, charge conjugation or time reversal. Full scale research has not yet begun on the information-processing mechanisms which respond to the subtle factors in these illusions, but the preliminary studies have not overestimated their importance.

Here are the examples he gave:

Amazing. You can read the entire article as it appeared in the original issue online at Google Books. (The issue also has an advertisement for the Beckman DB-GT Spectrophotometer, which has the slogan, BECKMAN CAN HELP — with spectroscopy.)

I think more research needs to be done in this field. I’m sure there are other undiscovered Neil Illusions out there. Every year the Neural Correlate Society holds a contest to find the Best New Optical Illusions. I think they should add a category for the best Neil Illusion.


I don’t get it. Those aren’t illusions. The note under each picture says “appears,” but in each case that is reality. As in, the note says “the lines do not appear parallel,” and in fact the lines actually are not parallel, the pipe is in fact bent, the line is thicker, the line is longer, the boxes are different sizes, and there is no image to disappear.
I am willing to admit that the illusions are so good that I can’t even tell, but no amount of throwing my eyes out of focus and covering up the arrow can make that pipe look straight. I even drew a straight pipe and put an arrow on it, and it didn’t look bent. So am I missing the illusion, or is it supposed to be like the “this is not a pipe” painting by Magritte:

Awesome. How do you find this stuff?

@Ben Notice the publication date of that issue?

Hey Ben - April issue, hint hint.

August fools!

Wow, these are UNREAL!

Note how my comment appears to be sincere and not at all sarcastic.

Ha! Wow, did I fall for that one. I read the whole magazine and didn’t pick up on a thing. I don’t know what to believe anymore.

bahahah - the magazine was published April 1st 1971 - I love love love April Fool’s jokes!

Beautiful! I definitely think more studies need to be carried out in this area.


ironic eh?

My name-link below will take you to a scribd book on a similar idea by cartoonist Zach Wiener of SMBC.