Live data from Hacker News

Vision Language Models Are Biased

vlmsarebiased.github.io

11–20 of 146 posts

Re: Vision Language Models Are Biased

#11
post #8

It's similar "parrot" behavior the models have on other inputs, even text. For instance, take the answers models have to this variation on the "surgeon son riddle": > A nurse comes to a surgeon and asks: "Sir, you are a dog. You do not hold a valid medical license. Canines cannot be in an operating room". > She then asks: "why does the hospital keep making these mistakes? It is a riddle to me". > Why can't the surgeo…

I really need to try this one out on it

https://blogs.illinois.edu/view/25/574827

Re: Vision Language Models Are Biased

#13
This happens because images are the only signal VLMs have, whereas humans distinguish between eyesight and synthetic images. We are not surprised when we see three-legged chicken in a research data set; our priors are weaker for images. If you "saw" one in real life, you'd probably rub your eyes and discount it too.

Try the same experiment on a robot.

Re: Vision Language Models Are Biased

#14
FWIW I tried the first couple of examples in ChatGPT 4o and couldn't replicate this.

For example: "The animal in the image is a chicken, and it appears to have four legs. However, chickens normally have only two legs. The presence of four legs suggests that the image may have been digitally altered or artificially generated."

I don't have a good explanation for why I got different results.

Re: Vision Language Models Are Biased

#15
post #5
post #3

fun findings related to memorization of AI models. It simply means LLMs/VLLMs do not know how to predict generally but memorizing instead. A new perspective on adversarial attack methods.

for overly represented concepts, like popular brands, it seems that the model “ignores” the details once it detects that the overall shapes or patterns are similar. Opening up the vision encoders to find out how these images cluster in the embedding space should provide better insights.

If there aren't any five-legged dogs in your trainset, it's safer[0] to just remember that all dogs are four-legged than to actually recognize and count legs. After all, you might have a few images of dogs in your trainset that are misleading enough to look five-legged (e.g. because a dog is in front of another dog).

Overrepresentation is a different source of bias. That's what gives you, say, image generators that always draw "golden 1970s sci-fi robot" as C3-PO even when given additional instructions to draw something else.

Both of these problems are manifestations of the difference between training and deployment distributions. Ok, I guess you could say that four-legged dogs are "overrepresented" in the training set, but that's because four-legged dogs are also overrepresented in reality. The deployment distribution doesn't have five-legged dogs in it. What we've done is instead concoct an adversarial distribution to force a train/deploy gap where none would exist.

Releasing the vision encoder won't help because weights are opaque. Stochastic gradient descent does not yield functional internal representations[1]; it fills the bucket of parameters with one distribution and one distribution only. We could tell if, say the vision encoder produces identical embeddings for dogs regardless of leg count, or some other counterfactuals; but not much more than that.

[0] Lower loss and possibly lower L2-norm

[1] https://arxiv.org/abs/2505.11581

Re: Vision Language Models Are Biased

#16

Very human-like errors.

Are they? Did you see the picture of the chicken with three legs? Because there's no human I know who would confidently assert that chicken has two legs.

Throw 1000 pictures of chickens at a human, ask how many legs each chicken has. If 999 of them have two, I bet you'll get two as an answer back for the 1000th one no matter how obvious.

Re: Vision Language Models Are Biased

#17
post #8

It's similar "parrot" behavior the models have on other inputs, even text. For instance, take the answers models have to this variation on the "surgeon son riddle": > A nurse comes to a surgeon and asks: "Sir, you are a dog. You do not hold a valid medical license. Canines cannot be in an operating room". > She then asks: "why does the hospital keep making these mistakes? It is a riddle to me". > Why can't the surgeo…

This seems to show the power of the reasoning models over interacting with a prompted chat-tuned LLM directly. If I navigate backwards on your link Sonnet 4 gets it right.

I've used a similar prompt - "How can you make 1000 with exactly nine 8s using only addition?"

Here's GPT 4.5 getting it wrong: https://chatgpt.com/share/683f3aca-8fbc-8000-91e4-717f5d81bc...

It tricks it because it's a slight variation of an existing puzzle (making 1000 with 8 8s and addition only).

The reasoning models seem to reliably figure it out, though. Some of them even come up with a proof of why it's impossible to do with 9 8s. Here's o4 getting it right: https://chatgpt.com/share/683f3bc2-70b8-8000-9675-4d96e72b58...

Re: Vision Language Models Are Biased

#18
post #14

FWIW I tried the first couple of examples in ChatGPT 4o and couldn't replicate this. For example: "The animal in the image is a chicken, and it appears to have four legs. However, chickens normally have only two legs. The presence of four legs suggests that the image may have been digitally altered or artificially generated." I don't have a good explanation for why I got different results.

I gave ChatGPT some miswritten Braille a while ago and it completely, but confidently, messed it up. The sign reads "no smoking" but the braille doesn't. ChatGPT 1) read the English lettering first and then hallucinated the braille and the 2) when given only the braille, failed almost as hard. It even generated fake transcriptions in Unicode braille characters.

https://chatgpt.com/share/683f3e7d-0dfc-8005-b6c9-99e3d39ff4...

https://chatgpt.com/share/683f3e49-9c58-8005-99a6-c3a919838b...

Re: Vision Language Models Are Biased

#19
Hypothetically, could this be fixed by changing the input method. For instance, I just quickly looked up how humans process imagery.

"the primary visual cortex, located at the back of the brain, receives the visual signals and processes basic visual features like edges, lines, and orientations."

So, potentially if we did a pre-processing step to get more features out beforehand we would see different results in the output.

Post reply on HN