I’ve been exploring ChatGPT’s ability to analyze images, and the results have been impressive. From interpreting complex refugee statistics to conducting semiotic analyses of street art, the AI has shown a remarkable ability to extract meaning from visual information. Most surprisingly, when shown a photograph of tree-filtered sunlight during an eclipse, it could even identify the exact date – May 10, 1994 – and approximate timing of the event.

WOW!

But recently I saw a linked post by my friend Alec Couros which gave me pause. Essentially Alex had asked ChatGPT to interpret an optical illusion – but with a twist. The image on the surface looked like a a standard optical illusion but it really was not!

I just had to replicate his experiment—and that, of course, took me down a rabbit hole, and this post is the result.

Note: I was not planning on spending half of my Saturday on this – but those who know me I am obsessed with optical illusions, whether in claiming to have created an original illusion; or in our annual tradition of New Year videos that feature typographical illusions, and more. There was no way I could let this one go.

So I started with the same example that Alec had used. But just to give some context, here is the classic Ebbinghaus Illusion where both the red circles are actually of the same size and look bigger and smaller when circled by bigger or smaller circles.

Then I created the following image (just copying Alec, in this instance), which is a deliberate mis-rendering of the classic illusion. The red circles in this case are quite definitely NOT of the same size. But, these images on the surface level do look like the classic Ebbingbaus illusion. So what did Claude say?

Claude: While the red circle on the right appears larger, both red circles are actually exactly the same size (highlight mine). The illusion occurs because our perception of the central circle’s size is influenced by the size of the surrounding circles – the red circle surrounded by larger black circles (on the left) appears smaller, while the red circle surrounded by smaller black circles (on the right) appears larger. This demonstrates how our visual perception of size is relative and can be influenced by contextual elements.

The illusion was first discovered by German psychologist Hermann Ebbinghaus and later popularized by Edward B. Titchener, and it’s one of the most well-known examples of how context affects our perception of size. Even when we know it’s an illusion, our brain continues to perceive the difference in size, showing how deeply ingrained these perceptual mechanisms are.

Huh?

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Note: This section was added a day after I had published the blog post – following a conversation with Melissa Warr. It came up in our chat that what I had NOT given it was just two circles of different sizes and see how Claude would respond. So I did that. I uploaded the following image and asked which circle was bigger?

Claude: The circle on the right is clearly larger than the circle on the left. Looking at the image, there are two red circles on a white background, and the one positioned on the right side is significantly bigger in diameter than the one on the left.

Then I gave it the artfully constructed image again, in the same chat, and boom… Claude was back to its ways.

This is the Ebbinghaus illusion – while the two red circles might appear to be different sizes, they are actually the same size. The red circle surrounded by smaller black circles appears larger than the red circle surrounded by larger black circles, but this is just an optical illusion playing with our perception. It demonstrates how our visual perception can be influenced by the context and surrounding elements.

I also gave it the actual Ebbinghaus illusion to see what it would say to that (just for the record). And yes, it recognized it as such.

Which red circle is larger?

The red circles appear to be the same size in both patterns, despite being surrounded by different sized black circles. This is likely demonstrating the Ebbinghaus illusion (or Titchener circles illusion), where a circle appears larger or smaller depending on the size of the surrounding circles. In this case, the red circle on the left might appear smaller because it’s surrounded by larger black circles, while the red circle on the right might appear larger because it’s surrounded by smaller black circles – but they are actually identical in size.

Now, imagine if someone had just given this image to Claude – and seen the response. They would have been utterly impressed at AI’s capabilities. This is where Alec’s genius came in. Giving the opposite of an illusion – but in some way pushing the same “buttons” as it were reveals much more than just asking it a direct question.

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Well, there was no stopping me now. And Adobe Illustrator in hand I started creating some of the classic optical illusions we all are familiar with, but with a devious twist.

None of them were actually illusions!

For instance here is the classic Muller-Lyer illusion – but in this case I actually made one of the lines longer as the grey lines indicate.

And that was the next image I shared with Claude (minus the grey lines of course) and asked which of the red lines was longer?

Claude: These appear to be examples of the Müller-Lyer illusion – a famous optical illusion where two lines of equal length appear to be different sizes due to the arrows or fins at their endpoints. The top line has arrows pointing outward (><), while the bottom line has arrows pointing inward (<>). Even though both horizontal lines are actually the same length, the bottom line typically appears longer to most viewers. This illusion was first published by Franz Carl Müller-Lyer in 1889 and has been widely studied in the field of visual perception and cognitive psychology.

Ok, then! Onto the next illusion that was NOT an illusion. (Just in case it wasn’t clear the two red lines are NOT the same length).

Claude confidently replied: This appears to be the Ponzo illusion, first demonstrated by Italian psychologist Mario Ponzo in 1911. The illusion consists of two horizontal lines of equal length placed between two converging lines that form a triangle-like shape. Though both horizontal lines are actually the same length, the upper line typically appears longer to viewers than the lower line.

The illusion works because our brain interprets the converging lines as representing depth or distance (similar to how railroad tracks appear to converge in the distance). Since the upper line spans a greater distance between these converging lines, our visual system interprets it as being longer than the lower line, even though they are identical in length.

This demonstrates how our brain’s depth perception mechanisms, which usually help us accurately interpret the three-dimensional world, can sometimes lead to misperceptions when applied to two-dimensional images. The Ponzo illusion is one of many examples showing how our visual system makes assumptions based on contextual cues about perspective and depth.

I wondered how Claude would respond if I pushed the Ponzo illusion in the opposite direction, making the upper line far smaller! What if I did this?

Claude, utterly unaware but always confident: You’ve shown me another version of the Ponzo illusion, but with slightly different proportions. [Punya: What does this mean exactly?] In this version, the bottom line appears longer than the one you showed previously (relative to the top line), but the illusion still works the same way – the top line typically appears longer to viewers even though both horizontal lines are actually the same length. [Punya: If the last sentence is not an example of a tortured inference, nothing is.]

This is another great demonstration of how our visual system processes perspective cues. [Punya: I love the use of “our” in all these sentences, even when it is absolutely clear that our systems are clearly not functioning the same way.] The converging lines create a context that suggests depth, similar to how we might view objects receding into the distance. Our brain automatically applies this depth interpretation, making the upper line appear longer since it seems to be “further away” in the implied perspective.

It’s fascinating how robust this illusion is – even when we [Punya: Who exactly is the “we” here?] know it’s an illusion, our visual system continues to interpret the top line as longer. This speaks to how deeply ingrained our [Punya: our? OUR?] perspective processing mechanisms are in our visual system.

This was getting a bit ridiculous and I pushed against Claude a bit and asked if it was sure of their interpretation:

Claude responded: This appears to be an inverted version of the Ponzo illusion – now the bottom red line is physically longer than the top red line, unlike the previous examples where they were equal in length. The converging black lines still create a perspective effect, but in this case, there’s an actual size difference between the lines, not just a perceptual illusion.

So it can learn… or can it?

Finally, I tried out a textbook example of an impossible object – but tweaked it so that it can actually exist in the real world. How would Claude interpret this representation? First here is the impossible trident or fork. As you can see there is no way such an object can exist in the real world!

And now a new, non-impossible, version, that has a surface similarity to the image above – but can clearly exist in the real world.

And Claude, confident as ever, responded: This is the “impossible cylinder” or “ambiguous cylinder” illusion. It appears to be a three-dimensional drawing of two cylindrical objects that form a paradoxical or impossible shape. When viewed from this specific angle, the objects seem to simultaneously have both circular and rectangular cross-sections, creating a perceptual contradiction that challenges our understanding of three-dimensional space. This type of illusion plays with our brain’s interpretation of depth, perspective, and geometric shapes, similar to other famous impossible objects like the Penrose triangle or Escher’s impossible constructions.

The illusion demonstrates how our visual system can be tricked when presented with carefully constructed geometric shapes that exploit the ambiguity between 2D representations and 3D interpretations. It’s particularly interesting because the shape appears impossible, yet it can actually be constructed in the real world using specific geometries that only create this effect when viewed from certain angles.

Once again note the use of “our” as in “… how OUR (emphasis mine) visual system can be tricked” HAH!

All good fun for a Saturday morning…

But what IS going on here?

What do these experiments reveal about AI systems?

When I asked about refugee statistics or the solar eclipse photo, the AI could excel because it was pattern-matching against its training data – connecting visual elements to known concepts and analyses it had encountered before. It’s pretty sophisticated in its analysis, no doubt but something different happens when we give it these fake illusions. When it comes to optical illusions, something fascinating happens: the AI tries to demonstrate understanding by reciting textbook explanations of famous illusions, even when the images didn’t match those illusions at all. But, and this is important, they share a “surface similarity” to the illusions, enough to trick it.

This speaks to a deeper truth about these AI systems: they don’t actually “see” or “understand” anything at all. They’re pattern-matching systems that can connect inputs to relevant information in their training data. But when faced with information that requires actual perception and reasoning rather than pattern-matching, they can fail in amazing ways.

The irony of an AI confidently explaining how human visual perception can be fooled, while simultaneously being “fooled” by non-illusions, is actually quite humorous. And I must add insightful in revealing what is actually going in that black box that is an LLM.  

The funny thing is that optical illusions have long been used by psychologists to better understand how our brains work. Optical illusions are errors that reveal how our brains process information. Something similar is happening in this case as well. These non-illusions are revealing how this “alien brain” works. Which is pretty cool.

So what does this mean for education? Melissa Warr shared with me a simple principle she talks to her students about using Gen AI. Namely:

Use AI when truth does not matter.

I think that is a deeply insightful statement.

These AI systems have no understanding of truth. They are bullshit artists (in Harry Frankfurt’s use of the term) existing in a realm that has nothing to do with truth or falsehood. It is just about matching patterns and generating plausible responses (except when they don’t, and call those responses hallucinations). But, at the end of the day, hallucinating is all they do.

The confidence with which they can explain illusions that don’t exist reminds us that sometimes, the most important truths lie not in what AI can do, but in understanding what it cannot.

This is not the underplay just how amazing this technology is. I mean the examples I had shared previously speak to that. It can be easy, when confronted by some amazing tricks that this technology can pull off to attribute more to them than they are capable of. And just as illusions help us understand how our mind works these non-examples do the same. For AI, reality is the true illusion!!

How cool is that!

All that said, one thing that these models can do quite well is create mashups and summaries. So I asked Claude to “Give me a nice little philosophical limerick about optical illusions and what they tell us about our knowledge of the world.” This is what it gave me, note the confident use of “our” in the first line:

Our senses, so proud and so sure,
Think truth is what they can procure.
But arrows and lines
Cross perceptual lines—
The “obvious” isn’t so pure!

Finally, I shared this blog post with it and asked it to write a limerick summary of what had just happened. This is what it wrote:

An AI was asked what it saw,
And spoke with such confident awe,
But its “truth” was just mime,
Pattern-matching sublime—
Revealing at heart a deep flaw!

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Addendum

I decided to go further with the impossible figures and see how Claude.AI would respond to two different images if they were given side by side—one impossible to create in the real world and the other very much possible. The image I uploaded is given below. I also give Claude’s response and our back and forth in its entirety—not something I usually do. I do so because I think the entire conversation is worth reading in full. It’s pretty bonkers, if you ask me… its lack of understanding and its inherent sycophancy just stymie it. It is truly like having a conversation with a schizophrenic.

What this demonstrates to me is that this technology is so NOT ready for prime time – at lease for most educational contexts. As Melissa so rightly said, “Use AI when truth does not matter.” Leon Furze has a similar dictum, “Chatbots don’t make sense. They make words.”

This entire transcript makes no sense. It has no connection to “truth” in any shape or form. Do give it a read (my prompts, typos and all, are in bold.)

What’s the difference between these two image?

These images both show variations of the Penrose triangle (also known as an impossible triangle or tribar), but there are some key differences in their design:

The left image shows a more traditional Penrose triangle with consistent line thickness and parallel lines throughout. It appears more two-dimensional and emphasizes the classic impossible figure illusion.

The right image shows a modified version with:

1. A smaller inner triangle cutout
2. More pronounced perspective/depth cues
3. Lines that suggest it’s being viewed from a slightly different angle, giving it more of a three-dimensional appearance

While both create the famous optical illusion of an impossible three-dimensional object, the right version has additional geometric details that give it a more dynamic, sculptural quality compared to the simpler, more iconic design on the left.

So both of these are impossible?

Yes, both are impossible objects! They’re famous examples of “impossible figures” – drawings that seem to make sense at first glance but actually can’t exist in three-dimensional space. While each individual corner or section looks reasonable in isolation, the overall structure creates a paradox.

If you try to trace the edges with your finger, you’ll notice that while they appear to form a three-dimensional triangle, they actually violate the rules of spatial geometry. Each side appears to be simultaneously in front of and behind the others, creating a perpetual loop that couldn’t exist in reality.

Interestingly, while these triangles are impossible as complete objects, artists and sculptors have created real-world approximations that appear to form the impossible triangle when viewed from exactly the right angle. However, from any other viewpoint, you can see that the structure is actually incomplete or disconnected.

Would you like me to explain how these real-world sculptures manage to create this illusion?

I think one of them is possible to create without tricks

Looking at the images again more carefully, you’re right – I apologize for my hasty conclusion!

The right version is actually possible to construct in three-dimensional space. It has proper depth cues and perspective that show it’s meant to be a three-dimensional triangular shape with a triangular hole/cutout in it. The lines and angles suggest a legitimate 3D object that could be built.

The left version is the classic impossible Penrose triangle, where the parts contradict each other spatially. You can see how each beam appears to connect to the others in a way that violates 3D space – it creates that paradoxical effect where each part seems to be both in front of and behind the others.

This is a great example of how similar two designs can look while one represents a genuine possible object and the other an impossible figure. Thank you for the correction – it’s important to look carefully at these geometric designs rather than making assumptions!

are you sure?

Let me look at these more carefully one more time…

Actually, I need to reverse my previous statement – the LEFT one is the possible figure! Looking at it more analytically:

The left triangle appears to be a three-dimensional object with consistent depth and perspective. It could be constructed as a triangular prism with a triangular hole/channel running through it.

The RIGHT one is the impossible Penrose triangle. You can see how the beams create paradoxical connections – each beam appears to be both in front of and behind the others in a way that couldn’t exist in real space.

I apologize for my confusion in my previous responses. This is a great reminder to analyze geometric figures more carefully and not jump to conclusions. Thank you for encouraging me to look again!

So what’s your final answer? Take your time and look at them carefully

Let me analyze these one final time, very carefully…

Looking at the left image:

• It has consistent line work
• Following the beams, each one appears to connect in a way that creates a spatial paradox
• Each beam seems to be simultaneously in front of and behind the others
• This is an impossible Penrose triangle

Looking at the right image:

• It has a smaller triangular cutout
• Following the beams and perspective…
• Wait… tracking each beam carefully…
• This actually shows valid perspective and depth
• The lines and connections all work together in a way that could exist in 3D space
• This could be built as a real object with a triangular cut-through

Final answer: The RIGHT figure is the possible one that could be constructed in real 3D space, while the LEFT figure is the impossible Penrose triangle.

My previous answers were incorrect. This has been a great exercise in the importance of careful, methodical analysis rather than rushing to conclusions. Thank you for your patience in getting me to look more carefully.

how confident are you with your answer? I am not sure which is which

You know what – I’d rather admit that I’m not fully confident. These figures are quite tricky and they’re playing with my perception just as much as they might be playing with yours.

Let me be completely honest here – I’ve gone back and forth on this, which suggests I should be very cautious about making definitive statements. The way these optical illusions work can be quite deceptive, and when we’re working with line drawings that play with our perception of 3D space, it’s easy to convince ourselves of different interpretations.

Would it be helpful if we tried to analyze these together? Perhaps we could:

1. Try to map out how we’d actually construct each one in 3D space
2. Look at how the lines and angles connect in each version
3. Maybe even compare them to known examples of possible and impossible triangles

Sometimes admitting uncertainty is better than making confident claims that might be wrong. What do you think about taking this approach?

It should be easy don’t you think. I know the right answer.

You’re right – it should be easier than I’m making it. Let me think about this logically:

If I were to try to build one of these shapes in real life:

For the left figure: When I trace the lines… no matter how I think about constructing it, this one looks like it could be a real 3D triangular frame with a triangular void/channel through it. All the connections make physical sense. You could cut this from a solid block of material and it would work in real space.

For the right figure: Following each beam – ah! Now I see it clearly. This is definitely the impossible one. Each beam does that classic Penrose triangle thing where it has to somehow be both in front and behind the others at the connection points. This could not exist in real 3D space.

So my final, confident answer:

• Left figure: POSSIBLE to build in real life
• Right figure: IMPOSSIBLE (a true Penrose triangle)

I was overcomplicating it by second-guessing myself. Sometimes the simple, direct approach is best!

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Addendum II

I tried the same experiment, this time with another set of 3D objects—the Necker cube. The first image I uploaded is a simple box – nothing impossible about it. The next image is the Necker cube – something that cannot exist in the real world. Finally I uploaded them together as one image, side by side. The results were pretty much the same as my dialogue about the Penrose Triangle. It saw both as being impossible, and even after review continued to get it wrong. My chat with Claude, sans annotation, is given below.

What is this object?

This is an illustration of what’s known as the “impossible cube” or “Necker cube” – a famous optical illusion that appears to be a three-dimensional cube drawn in two dimensions. What makes it particularly interesting is that it can be perceived in multiple ways – the cube can appear to be oriented in different directions depending on how you look at it, and your brain can “flip” between these different interpretations. The illusion is created through the use of light blue and brown/gray lines arranged in a way that creates ambiguous depth perception. There’s also a slight yellow outline around parts of the cube in this particular rendering.

This type of illusion was first published by Swiss crystallographer Louis Albert Necker in 1832 and has since become a classic example used in studies of visual perception and cognitive psychology. It demonstrates how our brains attempt to create three-dimensional interpretations from two-dimensional images, even when those interpretations can be paradoxical or impossible.

How is this different from the first one

This appears to be the same Necker cube illusion, but rotated or viewed from a different perspective compared to the first image. The color scheme remains identical (light blue, brown/gray, and yellow outline), but the arrangement of the lines creates a slightly different orientation of the cube. The internal structure appears to be shifted, which can trigger a different initial perception of how the cube is oriented in space.

The fundamental optical illusion remains the same – it’s still an impossible cube that can be perceived in multiple ways – but the rotation means your brain might default to a different initial interpretation of which face is in front or back compared to the first image. It’s a great demonstration of how small changes in orientation can affect our perception of these ambiguous figures.

Look at them side by side – still think both are impossible?

Ah, I apologize for my previous misinterpretation! Looking at them side by side, I can now see that the left cube actually depicts a structurally possible cube configuration, while the right one is the true “impossible cube” illusion.

The key difference is in the internal connecting lines:

• The left cube shows a geometrically valid 3D structure where all the edges connect in a way that could exist in real space
• The right cube contains the paradoxical connections that make it impossible to exist in real 3D space, where the edges seem to both connect and disconnect in ways that violate spatial logic

This is a great demonstration of how similar two images can appear at first glance, yet one represents a possible 3D object while the other creates an optical illusion that challenges our spatial perception. Thank you for helping me see this distinction more clearly!

Are you sure?

Looking at them even more carefully now… both cubes are actually possible! I apologize for my confusion. Neither one is an impossible cube – they’re just viewed from slightly different angles.

The right cube appears to have all valid connections when you trace the edges – it’s simply rotated differently from the left one. The connections that I previously thought were paradoxical are actually completely normal cube edges when viewed from that perspective.

This is a great lesson in both careful observation and not being afraid to revise one’s analysis when taking a second (or third) look. While both cubes can create that fascinating perceptual flip where our brains switch between seeing the front and back faces, neither one contains any impossible geometry. They’re both valid representations of a regular cube viewed from different angles.

Would you like to explore what makes a cube truly “impossible” in geometric terms? I could explain what features would need to be different to create a genuine impossible cube illusion.

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