Category Archives: optical illusion

Optical illusion: the Troxler effect

Have a look at the video below, which demonstrates “the Troxler effect” or “Troxler fading”, a phenomenon that occurs when you try to stop the involuntary movements of your eye (“scanning”): As we focus on a certain point in our perception field, that point becomes the main object of our visual system. When a blurry stimulus […]

Still more on the color illusion

Well, a reader showed in an email that that the hearts in the illusion below really were very slightly different colors due to the compression algorithms used in making the image. (However, those slight differences do not account for the striking perceptual effect).  The reader who demonstrated this anomaly won an autographed book from Matthew. There […]

Yesterday’s optical illusion: the hearts are the same color!

On yesterday’s Hili Dialogue, I posted this tweet, an optical illusion provided by Matthew: There appear to be greenish hearts and bluish ones, though they are the same color. — Akiyoshi Kitaoka (@AkiyoshiKitaoka) February 16, 2018 The hearts are said to be the same color, with the illusion of their being different colors due […]

Here’s the explanation!

by Matthew Cobb Here’s the explanation of the Mephisto illusion I posted earlier today… Cunning, eh?

Explain this illusion!

by Matthew Cobb Here’s a great illusion, known as the Mephisto Spiral. How does it work? Answers in the comments, please. And no peeking or googling! I’ll post the answer later on today.

Friday: Hili dialogue

OMG: it’s Friday the 13th (October, 2017), supposedly an unlucky day. But the odds are there will be at least one such day per year given that there are 12 thirteenths per year and only seven days of the week. And yesterday, at least, was lucky for the Chicago Cubs, who won the Central Division […]

Saturday: Hili dialogue

It’s Caturday, September 16, 2017, and in a few hours I’ll haul my weary carcass to the Chopin Airport in Warsaw for the nine-hour flight back to Chicago. That means, of course, that posting will be light today. If my plane crashes, it’s been a good run. If it doesn’t, let’s hope the airplane movies […]

The Coffer illusion

Okay, look at the photo of the door below. Time yourself from the start to see how long it takes you to find the circles. How many circles do you see? Do you see any? There are sixteen circles. Do you see them? If you don’t, and for an explanation, go to the next page […]

Wednesday: Hili dialogue

Good morning on Wednesday, May 17, 2017: exactly one week till I engage Le Dawkins in conversation in Washington, D.C. Be there or be square! Also, today the Certified Hand Therapist will inspect my finger to see if the tendon has healed enough that I can discard the damn plastic cast I’ve been wearing for six […]

A traveling-bar illusion

Matthew, who loves illusions, sent me this tw**t: Reality shatter. The two objects are traveling in exactly the same manner. Watch when it turns gray. — Cliff Pickover (@pickover) June 18, 2016 Now an explanation for this is published here (it’s based, as you might expect, on differences in contrast), but I can’t be arsed […]