# Professor explains whether cat is going up or down stairs

Technically Incorrect: An image of a cat on the stairs has captivated the Web and divided lovers and families. It needs an academic to sort it out.

Technically Incorrect offers a slightly twisted take on the tech that's taken over our lives.

It's been like Democrats and Republicans after three quarts of wine-in-a-box.

It's been almost as bad as Red Sox and Yankees fans litigating the trade of Babe Ruth.

For the last 48 hours, the world has been divided between those who think the cat is going upstairs and those sure it's on its way down.

Should you be unaccountably intelligent and therefore have missed this global schism, the cat image was first posted to 9Gag.com. It then hurtled into the world, with some believing that, quite clearly, the cat was descending and others thinking these people were three legs short of a tabby.

It would need a true academic to sort this one out. Thankfully, Behavioral Science professor Nick Chater of the Warwick Business School in the UK has risen to the task.

He contacted me to explain: "We see in 3D, even though our eyes only receive 2D images. This seems puzzling, because it can be shown mathematically that there is an implied number of 3D scenes that will create the same 2D images. Most of the time, our brain is spectacularly good at solving this problem. It usually turns out that precisely one 3D interpretation is 'sensible' and all the others are bizarre, in one way or another."

I am surrounded by bizarre images all day. I think of them as mere normality. After all, I live in Northern California.

However Chater continued: "Our brain uses the most 'sensible' 3D interpretation; and mostly -- except when we are being subjected to cunning visual illusions -- this works just fine. But sometimes there are two equally plausible 3D interpretations of the same 2D image. Famous examples include the Necker cube (http://en.wikipedia.org/wiki/Necker_cube) and Rubin's face-vase illusion (http://en.wikipedia.org/wiki/Rubin_vase). Then, the brain flips between one interpretation and the other."

Professor, my brain is flipping. Tell me, is the cat going up or down the stairs?

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Chater explained that the cat image has two possible interpretations because of "the amorphous gray square at the top of the picture." He suggests we focus on "the angle between the plane of the staircase and the surface represented by this gray patch."

He told me: "When we see the cat as coming downstairs, the gray square is interpreted as ceiling -- and this makes an acute, roughly 45 degree, angle with the staircase. But when we see the cat as going upstairs, the gray square is now interpreted as floor -- and this makes an obtuse, roughly 135 degree angle with the staircase."

So which is it, professor? Up or down?

"If we could only tell the 'slant' of the mysterious square patch in relation to the staircase, we would know if it was floor or ceiling, and so there would be no ambiguity. But the image cleverly leaves the gray square bereft of any clues. So we flip from one interpretation to the other," he said.

What do you mean: "If only"? After all this intellectual explanation, we still don't have an answer? Worse, we will never have an answer unless the creators of this dastardly picture come forward and admit their bent?

How will we now get through the weekend?