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
Thanks Toby - looks like it needs to be approved first, must be a new thing from my recollection I thought it went live immediately...
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