Pascal Mamassian
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mamassian.bsky.social
Pascal Mamassian
@mamassian.bsky.social
I’m studying visual perception, mostly using psychophysics. I work for the CNRS at the Ecole Normale Supérieure in Paris.
We found that motion features were encoded in a temporally ordered sequence: orientation and spatial frequency emerged within 120 ms after stimulus onset, while temporal frequency and direction followed at later latencies.

[2/3]
September 26, 2025 at 4:41 PM
A nice shift in perceived colour between central and peripheral vision. The fixated disc looks purple while the others look blue.

The effect presumably comes from the absence of S-cones in the fovea.

From Hinnerk Schulz-Hildebrandt:
arxiv.org/pdf/2509.115...
September 24, 2025 at 12:04 PM
The model can also fit continuous confidence ratings without binning these ratings.

Matlab code here: github.com/mamassian/cn...

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April 22, 2025 at 1:53 PM
Critically, the model includes a parameter that reflects whether confidence relies on the same information that was used for perceptual decisions, or some new information. We describe two ways to estimate this Confidence Boost parameter.

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April 22, 2025 at 1:52 PM
The CNCB (Confidence-Noise Confidence-Boost) model can be seen as an alternative to the popular meta-d’ and M-ratio analyses. It can take more than two stimulus strengths and is a bit more tolerant to sensory biases.

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April 22, 2025 at 1:52 PM
If you work with perceptual confidence judgments, you may be interested in our CNCB model of confidence ratings. Joint work with Vincent de Gardelle.

Uncorrected proofs here:
dx.plos.org/10.1371/jour...

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April 22, 2025 at 1:51 PM
Why is it so difficult for Large Language Models to properly read time?

arxiv.org/abs/2502.05092
April 12, 2025 at 1:34 PM
The dynamic version is even more disturbing...
March 12, 2025 at 2:29 PM
Congratulations!

Richard Gregory probably helped to popularize the cultural hypothesis in his nice 1966 book “Eye and Brain”.

But since then, isn’t the dominant theory related to a misuse of the low spatial frequency content of the image (its blurred part)?

See e.g. doi.org/10.1068/p150...
January 27, 2025 at 8:54 AM
I agree that the coming and going of 3D perceptions makes this animation interesting!

A nice development on the “stereokinetic effect” of Cesare Musatti a century ago, and more recently of the work of Zili Liu (UCLA):
doi.org/10.1016/j.vi...

original post here:
bsky.app/profile/jcpo...
January 24, 2025 at 8:10 AM
Interestingly, another model, “GPT-4o”, is also biased like humans, but it can generate some python code to analyse the image pixel by pixel to correct its error

Overall, I agree with Tomer that it is not clear why we would want these models to fall for illusions the way humans do.

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December 22, 2024 at 11:49 AM
The model also “knows” that the effect is orientation dependent

www.sciencedirect.com/science/arti...

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December 22, 2024 at 11:49 AM
As predicted, it is also reporting the illusion when the lines are un-equal (“illusion-illusion”), and it explicitly refers to the vertical-horizontal illusion.

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December 22, 2024 at 11:49 AM
Very interesting analysis!

I have tried the vertical-horizontal illusion in its classic configuration. The model “Claude” is reporting the human-biased percept when the lines are physically equal (“illusion”)

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December 22, 2024 at 11:49 AM
Cast shadows are indeed so powerful!

Here is another related picture from the following chapter that Dan Kersten and I wrote:
hal.science/hal-03984071/
December 8, 2024 at 11:01 AM
It was nice to see that many people interested in time perception at the first FAsT (French Association for Timing) meeting in Saclay last week!
fast2024.sciencesconf.org
October 21, 2024 at 3:00 PM
Happy to share the results of interdisciplinary discussions between scientists and artists on colour (in French) — Heureux de partager les résultats de discussions interdisciplinaires entre scientifiques et artistes sur la couleur (en français)
doi.org/10.3917/herm...
November 27, 2023 at 12:59 PM