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Steven

@stevengeysen.bsky.social
105 followers 485 following 19 posts

(he/him) PhD student @peterslab.bsky.social, University of Cologne, Germany Cognitive psychology - (risky) decision-making

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Reposted by Steven
Al Yankovic @alyankovic.bsky.social · 31/08/2026
“Lost media” no longer! I finally got permission to upload “AL’S BRAIN,” an 11-minute educational 3-D film attraction which ran at the Orange County and Western Washington fairs, and hasn’t been seen publicly since 2009. You can watch the whole thing here: youtu.be/2xujU87ZHt4
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Reposted by Steven
Imaging Neuroscience @imagingneurosci.bsky.social · 11/08/2026
New paper in Imaging Neuroscience by Steven Geysen, Jan Peters, et al: Human risk taking and metabolic state: No credible evidence for desacyl-ghrelin modulation of neural or behavioural effects doi.org/10.1162/IMAG...
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Steven @stevengeysen.bsky.social · 07/08/2026
Thanks to the comments from the reviewers, and the help of all my coauthors (Ella Brands, @heidrunschultz.bsky.social , @koeniglab.bsky.social , Marc Tittgemeyer and @peterslab.bsky.social ), this preprint turned into my first publication doi.org/10.1162/IMAG...
doi.org
Human risk taking and metabolic state: No credible evidence for desacyl-ghrelin modulation of neural or behavioural effects
Abstract. Risk taking has often been proposed to depend on homeostatic systems. However, empirical evidence remains inconsistent, and the underlying mechanisms remain debated. Changes in risky decisio...
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Reposted by Steven
Dil Korkmaz @dil-k.bsky.social · 06/06/2026
New preprint out 🌿 www.biorxiv.org/content/10.6... With Qingyue Bi, Michelle Moller, Julian Koenig, @peterslab.bsky.social
biorxiv.org
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Ben Jonathan Wagner @benjwagner.bsky.social · 30/05/2026
We @saschafrolich.bsky.social @stefankiebel.bsky.social investigated how habitual- and goal-directed control interact when actions must be made under time pressure. www.nature.com/articles/s44...
nature.com
Context-dependent interaction between goal-directed and habitual control under time pressure - Communications Psychology
This study investigates the dynamic interplay between habitual and goal-directed control. Using RL and drift-diffusion modelling, we show that these systems interact in a context-dependent manner: hab...
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Reposted by Steven
Ben Jonathan Wagner @benjwagner.bsky.social · 27/11/2025
Very happy that this is out www.nature.com/articles/s44.... Together with @stefankiebel.bsky.social we show that decision biases in context-dependent decision making, previously attributed to different forms of value normalization, are very well explained by habit-like action repetition.
nature.com
Action repetition biases choice in context-dependent decision-making - Communications Psychology
This study shows that decision biases previously attributed to value normalization (e.g. relative value learning or range normalization) are better explained by action repetition. Repeating an action ...
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Reposted by Steven
annecollins.bsky.social @annecollins.bsky.social · 17/11/2025
My paper is out! Computational modeling of error patterns during reward-based learning show evidence that habit learning (value free!) supplements working memory in 7 human data sets. rdcu.be/eQjLN
rdcu.be
A habit and working memory model as an alternative account of human reward-based learning
Nature Human Behaviour - In this study, Collins proposes an alternative dual-process (working memory and habit) model of reinforcement learning in humans.
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Steven @stevengeysen.bsky.social · 22/10/2025
‼️New preprint‼️ There does not seem to be an effect of ghrelin on risky decision-making in probability discounting. Not in behaviour, underlying computational processes, or neural activity. More details ⬇️
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Steven @stevengeysen.bsky.social · 13/08/2025
Today I will present some of our lab's work at #CCN2025 In two separate studies, we investigated the effect ghrelin, the hunger hormone, on probability discounting. We manipulated ghrelin levels by fasting (study 1) and 1 night if sleep deprivation (study 2) More information and figures on poster 80
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Steven @stevengeysen.bsky.social · 05/12/2024
2 years ago I built a fMRI preprocessing pipeline for ADNI data. Now I can share the work that was done with it. Riccardo Leone, in the lab of Xenia Kobeleva, used it to model the effects of white matter hyperintensities using whole-brain modelling 🧠💻🧠📈 onlinelibrary.wiley.com/doi/10.1002/...
onlinelibrary.wiley.com
Beyond Focal Lesions: Dynamical Network Effects of White Matter Hyperintensities
By combining whole-brain neural mass modeling with a virtual-lesioning approach informed by empirical WMH lesion masks, we provide evidence that WMH induce changes in brain dynamics by reducing the g...
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Steven @stevengeysen.bsky.social · 10/05/2024
From our lab!
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