Paul Sharp
@paulbsharp.bsky.social
1K followers 290 following 210 posts
Assistant professor of psychology, Bar-Ilan University | computational cognitive science & psychiatry "Discovery happens less when you're trying to be the expert and more when you're trying to be the learner." - Itai Yanai Website: sharplabbiu.github.io
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paulbsharp.bsky.social
🚨 Clinicians have noted for decades how planning & anxiety are linked. Yet, computational psychiatry thus far failed to show how. Here, I explain that we need to broaden how we model planning to reveal its *biases* in chronic anxiety. A 🧵 on the framework 1/n

authors.elsevier.com/a/1kAJC4sIRv...
paulbsharp.bsky.social
This was my first mentoring journey with my super-talented BA student, Hadas Schiff (not on bsky; congrats Hadas!!!!).

And what a beuatiful day to share this, when the hostages are freed, and finally, there seems to be hope for peace. ☮️🕊️

#computationalpsychiatry

We look forward to feedback!
paulbsharp.bsky.social
We plan on building a computational model, and larger-scale test, inspired by work by @thecharleywu.bsky.social , @markkho.bsky.social and others on how we build task representations under uncertainty.

This is small, preliminary but promising evidence requiring replication!

11/12
paulbsharp.bsky.social
This helps explain anxiety maintenance: By under-generalizing their behavioral repertoire in threat-related domains, anxious individuals restrict exploration, miss opportunities to disconfirm maladaptive beliefs, and perpetuate avoidance.
10/12
paulbsharp.bsky.social
Implication: When an awkward social moment coincidentally co-occurs with your actions (like speaking up when a bell rings), anxious individuals may preclude that behavioral strategy from future task models.
"If I speak up → bad things happen" even when the relationship is spurious.
9/12
paulbsharp.bsky.social
This wasn't about reinforcement history.
Only 1 participant in Study 1 hit an obstacle in training. In Study 2, 5 participants hit obstacles (<1% of steps). Removing them preserved all effects.
The bias stems from how threat information distorts task representation, not reinforcement.
8/12
paulbsharp.bsky.social
Why does this matter? The bias was differential: Under-generalization hurt performance when facing new instances of threat-related tasks (where that knowledge would be useful) but helped slightly with safe tasks.
Worry predicted worse generalization for threat vs. safe contexts (see Figure 4).
7/12
paulbsharp.bsky.social
This is under-generalization, not over-generalization—the opposite of what we see in perceptual fear conditioning!
When making planning errors, high-worry individuals were LESS likely to reuse actions associated with threat contexts, excluding behavioral repertoires from their task models.
6/12
paulbsharp.bsky.social
People successfully generalized above chance.
But: Individuals high in trait worry showed systematic under-generalization specifically for the task category that had been paired with threat during training.
Study 1: ρ = 0.43, p = 0.11
Study 2: ρ = 0.53, p = 0.02 (replication with harder task)
5/12
paulbsharp.bsky.social
In a planning phase, participants saw NEW vehicles and had to plan 4-step sequences without feedback. Success required correctly inferring the task category of the vehicle.
We tested higher-order generalization ( a car or truck?) and lower-order generalization (which specific car?).
4/12
paulbsharp.bsky.social
Participants could easily avoid the fire obstacles during training—and they did! We're not measuring learning deficits or avoidance behavior during training.
Instead, we're asking: Does the mere co-occurrence of threat + actions bias how people later represent and generalize task structure?
3/12
paulbsharp.bsky.social
Participants learned to control different vehicles (cars vs trucks) in a grid world. Each vehicle type had unique key mappings defining how it moved—essentially, different "task model" transition functions.
1 type was randomly paired w social threat (fire = more time public speaking😬).
2/12
paulbsharp.bsky.social
1st Sharp Lab preprint! 🚨 We tested how anxiety affects task generalization—not how people generalize threat stimuli, but how they reuse action-outcome structures when planning in new contexts.

Worry makes people avoid reusing actions that co-occurred w/ threat!
📄: osf.io/preprints/ps...

🧵 1/12
Reposted by Paul Sharp
markkho.bsky.social
I'm recruiting grad students!! 🎓

The CoDec Lab @ NYU (codec-lab.github.io) is looking for PhD students (Fall 2026) interested in computational approaches to social cognition & problem solving 🧠

Applications through Psych (tinyurl.com/nyucp) are due Dec 1. Reach out with Qs & please repost! 🙏
codec lab
codec-lab.github.io
Reposted by Paul Sharp
eraneldar.bsky.social
Happy to share our new work showing how social emotions such as anger and gratitude establish an interindividual form of actor-critic learning, which leads to the emergence of norms in groups of interacting individuals.

Now published at @apajournals.bsky.social: psycnet.apa.org/record/2026-...
Reposted by Paul Sharp
joshcjackson.bsky.social
🚨New preprint🚨

osf.io/preprints/ps...

In a sample of ~2 billion comments, social media discourse becomes more negative over time

Archival and experimental findings suggest this is a byproduct of people trying to differentiate themselves

Led by @hongkai1.bsky.social in his 1st year (!) of his PhD
paulbsharp.bsky.social
Looks super cool, looking forward to reading.
zachrosenthal.bsky.social
Super proud of this collaboration with rockstar Ryan Raut - born out of playing in the sandbox in our last year of grad school! Multi-scale brain activity can be predicted from a simple measure of arousal like pupil diameter. Out with linear causality, in with dynamic systems to explain neurobiology
Arousal as a universal embedding for spatiotemporal brain dynamics - Nature
Reframing of arousal as a latent dynamical system can reconstruct multidimensional measurements of large-scale spatiotemporal brain dynamics on the timescale of seconds in mice.
www.nature.com
Reposted by Paul Sharp
ondrejzika.bsky.social
🚨 I am over the moon 🌓 to announce that I am joining University College Dublin @ucddublin.bsky.social as an Assistant Professor this fall to start the Uncertain Mind (UMI) lab 💫

I am looking for PhD/Postdoc candidates to join (more below 👇 ). Please RT as the deadline is pretty soon 🙏
paulbsharp.bsky.social
This problem pervades many areas

Kozak and Miller 1982 have a great paper on this: "Hypothetical constructs versus intervening variables: A re-appraisal of the three-systems model of anxiety assessment"

psycnet.apa.org/record/1983-...
Reposted by Paul Sharp
malcolmgcampbell.bsky.social
🚨Our preprint is online!🚨

www.biorxiv.org/content/10.1...

How do #dopamine neurons perform the key calculations in reinforcement #learning?

Read on to find out more! 🧵
Reposted by Paul Sharp
tobigerstenberg.bsky.social
🚨 NEW PREPRINT: Multimodal inference through mental simulation.

We examine how people figure out what happened by combining visual and auditory evidence through mental simulation.

Paper: osf.io/preprints/ps...
Code: github.com/cicl-stanfor...
Reposted by Paul Sharp
saurabhbedi.bsky.social
📢 Preprint out! biorxiv.org/content/10.1... What gives rise to probability weighting, a cornerstone of Prospect Theory?
We show it comes from the natural boundedness of probabilities + cognitive noise. Adding boundaries adds multiple distortions, across risky choice & perception.
Probability weighting arises from boundary repulsions of cognitive noise
In both risky choice and perception, people overweight small and underweight large probabilities. While prospect theory models this with a probability weighting function, and Bayesian noisy coding mod...
biorxiv.org
Reposted by Paul Sharp
pf-hitchcock.bsky.social
Now out in JEP: General, "How working memory and reinforcement learning interact when avoiding punishment and pursuing reward concurrently"

psycnet.apa.org/record/2026-...

Preprint with final version: osf.io/preprints/ps...

1/n
Reposted by Paul Sharp
Reposted by Paul Sharp
annamai.bsky.social
Out now in Neuroscience & Biobehavioral Reviews!

When studying language in the brain, we often look for things that can be model systems for language (songbirds, artificial grammars, etc.). Here, we flip this on its head and argue that language itself is an excellent model system for cognition 🗣️🧏‍♀️🧠