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Sebastian Hellmann

@sehellmann

PostDoc working at TU Munich. Interested in on computational modelling, decision-making, and confidence. Cat owner, Ireland lover and brass music fan

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03.11.2023
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Latest posts by Sebastian Hellmann @sehellmann

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Stimulus reliability but not boundary distance manipulations violate the folded-X pattern of confidence The folded-X pattern has been identified as a critical signature of confidence: as conditions become easier, confidence increases for correct trials b…

Our new paper is out in Cognition! What determines whether confidence follows the classic "folded-X" pattern vs. the "double-increase" pattern? The answer lies in the type of stimulus manipulation. Big thanks to my advisor Doby @dobyrahnev.bsky.social and co-first author @herrickfung.bsky.social !

25.02.2026 00:33 πŸ‘ 21 πŸ” 7 πŸ’¬ 1 πŸ“Œ 1

Yesterday, we finally got to celebrate the successful PhD defense of our PostDoc @maryamtohidi.bsky.social at a delicious Iranian restaurantπŸ˜‹
We are so proud of Dr Tohidimoghaddam, who continues her journey with us elucidating multi-attribute decision-making🧠 Stay tuned for her future contributions!

25.02.2026 09:29 πŸ‘ 9 πŸ” 1 πŸ’¬ 0 πŸ“Œ 1
'If you've eliminated a few possibilities and you can't think of any others, your weird theory is proven right' isn't quite as rhetorically compelling.

'If you've eliminated a few possibilities and you can't think of any others, your weird theory is proven right' isn't quite as rhetorically compelling.

Eliminating the Impossible
https://xkcd.com/3210/

'If you've eliminated a few possibilities and you can't think of any others, your weird theory is proven right' isn't quite as rhetorically compelling.

Explain xkcd: https://www.explainxkcd.com/wiki/index.php/3210

20.02.2026 20:13 πŸ‘ 8 πŸ” 4 πŸ’¬ 1 πŸ“Œ 3

poor bee GOLD_07, whose embarrassing mistake has been immortalised in a way beyond his comprehension

17.02.2026 21:19 πŸ‘ 30 πŸ” 10 πŸ’¬ 2 πŸ“Œ 0
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Compositional data (proportions that sum to 1) behave in ways standard models aren’t built for

I walk through why Dirichlet regression is often the right tool & what extra insight it gives using a real ex of eyetracking

#Dirichlet #r #brms #guide #eyetracking

open.substack.com/pub/mzlotean...

09.02.2026 16:05 πŸ‘ 23 πŸ” 11 πŸ’¬ 2 πŸ“Œ 0

How do priors influence speech processing? Do they enhance expected signals or highlight the unexpected (prediction errors)? @fabianschneider.bsky.social' s work shows: It depends!

12.01.2026 13:02 πŸ‘ 15 πŸ” 8 πŸ’¬ 0 πŸ“Œ 0
article cover page and abstract

article cover page and abstract

New article in Cognitive Psychology with @thorstenpachur.bsky.social and Veronika Zilker: β€œHow sampling strategies shape experience-based risky choice.”

We present a computational framework for information search and choice in decisions from experience. 1/4
doi.org/10.1016/j.co...

17.12.2025 10:32 πŸ‘ 20 πŸ” 6 πŸ’¬ 1 πŸ“Œ 1
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Can Your Face Predict Your Salary? Using AI Personality Assessments in Hiring A new study from Wharton faculty explores how AI can extract personality traits from facial images β€” and what that means for your career.

Computer scientists: "So with machine learning we can extract subtle patterns from massive datasets. What shall we do with it?"

Business school professors, every single time: "You know, I think phrenology got a raw deal in the late 1800s."

11.12.2025 19:36 πŸ‘ 1378 πŸ” 445 πŸ’¬ 43 πŸ“Œ 43
Apply - Interfolio {{$ctrl.$state.data.pageTitle}} - Apply - Interfolio

Well this is exciting!

The Department of Psychological & Brain Sciences at Johns Hopkins University (@jhu.edu) invites applications for a full-time tenured or tenure-track faculty member in Cognitive Psychology, in any area and at any rank!

Application + more info: apply.interfolio.com/178146

02.12.2025 03:18 πŸ‘ 93 πŸ” 55 πŸ’¬ 1 πŸ“Œ 3
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GrΓΌne vollziehen Kehrtwende bei der HomΓΆopathie Am ersten Tag des GrΓΌnen-Parteitags in Hannover wird es lebhaft: Ein Antrag wird angenommen, der die Finanzierung homΓΆopathischer Leistungen durch gesetzliche Krankenkassen untersagen will. Eine historische Kehrtwende.

GrΓΌne vollziehen Kehrtwende bei der HomΓΆopathie: Am ersten Tag des GrΓΌnen-Parteitags in Hannover wird es lebhaft: Ein Antrag wird angenommen, der die Finanzierung homΓΆopathischer Leistungen durch gesetzliche Krankenkassen untersagen will. Eine historische Kehrtwende.

28.11.2025 22:32 πŸ‘ 526 πŸ” 101 πŸ’¬ 22 πŸ“Œ 19
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Science in 2025

21.11.2025 13:38 πŸ‘ 45 πŸ” 12 πŸ’¬ 5 πŸ“Œ 2
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Still think this was one of the best power moves of all time

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

12.11.2025 00:32 πŸ‘ 318 πŸ” 65 πŸ’¬ 8 πŸ“Œ 9

πŸ“’ The #TeaP2026 talk & poster submission deadline is approaching fast! ⏰ Don’t miss your chance – submit your contribution by November 16: coms.app/teap26/ πŸ‘πŸΌ

12.11.2025 08:48 πŸ‘ 0 πŸ” 3 πŸ’¬ 0 πŸ“Œ 1
Foto von Paul Langerhans und Titel- und erste Seite seiner Doktorarbeit "BeitrΓ€ge zur mikroskopischen Anatomie der BauchspeicheldrΓΌse". Der Satz "Der einzige Zweck dieser Entstehungsgeschichte meiner Arbeit ist Motivierung und Entschuldigung ihres geringen Gehaltes." ist rot markiert.

Foto von Paul Langerhans und Titel- und erste Seite seiner Doktorarbeit "BeitrΓ€ge zur mikroskopischen Anatomie der BauchspeicheldrΓΌse". Der Satz "Der einzige Zweck dieser Entstehungsgeschichte meiner Arbeit ist Motivierung und Entschuldigung ihres geringen Gehaltes." ist rot markiert.

Wir starten mit der ersten Seite der Doktorarbeit von Paul Langerhans, dem Entdecker der pankreatischen Inseln. Lief wohl alles nicht so rund und ich mag diesen Satz sehr: "Der einzige Zweck dieser Entstehungsgeschichte meiner Arbeit ist Motivierung und Entschuldigung ihres geringen Gehaltes."

11.11.2025 07:29 πŸ‘ 29 πŸ” 3 πŸ’¬ 2 πŸ“Œ 0
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You can’t reboot the planet if you crash it What Gates is putting forward aren’t legitimate arguments that can be made in good faith. They are shopworn fossil fuel industry talking points.

"You can’t reboot the planet if you crash it" | My commentary on Bill Gates' flawed new climate missive for @thebulletin.org: thebulletin.org/2025/10/you-...

31.10.2025 18:35 πŸ‘ 1171 πŸ” 455 πŸ’¬ 60 πŸ“Œ 39

Another good reason to kill this whole industry now. It’s going to fail anyway, we may as well do so while we still have a chance to restore the planet.

28.12.2024 22:39 πŸ‘ 31 πŸ” 12 πŸ’¬ 1 πŸ“Œ 1
AI Slop Is Destroying The Internet
AI Slop Is Destroying The Internet YouTube video by Kurzgesagt – In a Nutshell

Kurzgesagt - in a nutshell explains perfectly why AI in such Context is really problematic.

Also John Oliver from Last week tonight did a really good video about AI Slop and how many think it's real.

27.10.2025 20:49 πŸ‘ 6 πŸ” 3 πŸ’¬ 1 πŸ“Œ 0
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For your enjoyment (by @jagarikin)

25.10.2025 11:58 πŸ‘ 136 πŸ” 40 πŸ’¬ 5 πŸ“Œ 6

Our new paper is out as a reviewed preprint in @elife.bsky.social!

elifesciences.org/reviewed-pre...

Congrats to @hashimsat.bsky.social and our amazing collaborators on this great team effort.

Special shout-out to @haukeren.bsky.social, who made this possible through his generous support πŸ™Œ

21.10.2025 06:41 πŸ‘ 20 πŸ” 6 πŸ’¬ 1 πŸ“Œ 1

Award-winning pain researcher here. This is not something that can be done. Hope this helps.

15.10.2025 14:02 πŸ‘ 2330 πŸ” 634 πŸ’¬ 60 πŸ“Œ 12
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Similarities and differences in the effects of different stimulus manipulations on accuracy and confidence Visual stimuli can vary in multiple dimensions that affect accuracy and confidence in a perceptual decision-making task. However, previous studies hav…

Glad to see my first-year project is out!

In two experiments, we manipulated multiple stimulus features in a perception task, yet their effects on confidence and accuracy fell into just two distinct behavioral patterns, offering a way to predict the effects of novel stimulus manipulations.

1/n

12.10.2025 16:10 πŸ‘ 22 πŸ” 8 πŸ’¬ 1 πŸ“Œ 1
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Characterising Cognitive Biases Elicited by Misinformation Using Reinforcement Learning at Queen Mary University of London on FindAPhD.com PhD Project - Characterising Cognitive Biases Elicited by Misinformation Using Reinforcement Learning at Queen Mary University of London, listed on FindAPhD.com

⭐PhD in Cognitive/Computational Psychology⭐, Please Share!! Use Reinforcement Learning and Computational Modelling to study how dis/misinformation affects us (with myself +Tali Sharot). Full funding for those eligible for UK home fees. Deadline 10th Nov. @queenmarycbb.bsky.social

08.10.2025 11:50 πŸ‘ 2 πŸ” 4 πŸ’¬ 0 πŸ“Œ 0
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If you’re in #Munich πŸ₯¨ and curious about decision-making, perception, and cognition through a translational lens, join us for a seminar I’m hosting on Oct 30 with three fantastic speakers: @jkesby.bsky.social (visiting from πŸ‡¦πŸ‡Ί), @miguelbengala.bsky.social, and @jacob-lab.bsky.social πŸ§ πŸ’‘

28.09.2025 19:24 πŸ‘ 11 πŸ” 6 πŸ’¬ 3 πŸ“Œ 1
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Hosting a WebSite on a Disposable Vape Someone's trash is another person's web server.

you heard of running Doom on random gadgets but have you ever heard of…
β€œHosting a WebSite on a Disposable Vape”
bogdanthegeek.github.io/blog/project...
this explains how!
((the internet is healing 😌))
#IndieDev

28.09.2025 08:20 πŸ‘ 293 πŸ” 90 πŸ’¬ 2 πŸ“Œ 2

Just back from this - I was the misfit invited speaker who knows nothing about psychology. It was really educational for me, expanded my view of theory construction problems in the human sciences.

27.09.2025 08:06 πŸ‘ 29 πŸ” 2 πŸ’¬ 1 πŸ“Œ 0

Introducing hMFC: A Bayesian hierarchical model of trial-to-trial fluctuations in decision criterion! Now out in @plos.org Comp Bio.
led by Robin Vloeberghs with @anne-urai.bsky.social Scott Linderman

Paper: desenderlab.com/wp-content/u... Thread ↓↓↓

#PsychSciSky #Neuroscience #Neuroskyence

25.09.2025 09:13 πŸ‘ 51 πŸ” 30 πŸ’¬ 3 πŸ“Œ 0

"Learning to be confident: How agents learn confidence based on prediction errors"! Now out in @cognitionjournal.bsky.social led by @pierreledenmat.bsky.social

Paper: desenderlab.com/wp-content/u... Thread ↓↓↓

#AcademicSky #PsychSciSky #Neuroscience #Neuroskyence

25.09.2025 08:44 πŸ‘ 19 πŸ” 7 πŸ’¬ 1 πŸ“Œ 0
An array of 9 purple discs on a blue background. Figure from Hinnerk Schulz-Hildebrandt.

An array of 9 purple discs on a blue background. Figure from Hinnerk Schulz-Hildebrandt.

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...

24.09.2025 10:16 πŸ‘ 770 πŸ” 296 πŸ’¬ 33 πŸ“Œ 53

Unfortunately, for the variance on the probability scale, the speed up vanishes.

23.09.2025 15:39 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Thanks for the kind words.
Glad to see that people already account for this in some packages. Not sure whether it helps a lot, but using the direct computations instead of using numerical integration may still speed up things a bit (about 20 times on my machine)

23.09.2025 15:39 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0