Christoph Strauch

Christoph Strauch

@cstrauch.bsky.social

Assistant professor @utrechtuniversity.bsky.social studying spatial attention, eye-movements, pupillometry, and more. Co-PI @attentionlab.bsky.social

636 followers550 following179 posts

Christoph Strauch reposted

Christoph Strauch reposted

Some months ago, I wrote a skeptical reply to a commentary on bots in online studies in PNAS, arguing that no evidence yet exists for such bots. Together with the authors of the original commentary, we now show that bots can pass (almost?) all online cognitive studies with human-like performance 1/n

Christoph Strauch@cstrauch.bsky.social

How much of a risk are LLM-generated bots for online behavioral experiments? We present results of an entirely natural language prompt-generated agent, capable of absolving any of the 26 experiments we tested it on. Most tasks are passed with data that can pass as human osf.io/preprints/ps... (1/)

Christoph Strauch reposted

🧵In April, I built an AI agent that could complete the Attention Network Task. The agent was task-specific and costly. I concluded that online behavioral experiments were safe from agentic infiltration. Six months later, my view has changed. Our new preprint explains why osf.io/preprints/ps...

osf.ioGeneralizable experiment agents threaten online behavioral experimentsOnline behavioral experiments rely on the assumption that participants are human. Advances in large language models (LLMs) challenge this assumption, but previous demonstrations have largely focused o...

Christoph Strauch reposted

How much of a risk are LLM-generated bots for online behavioral experiments? We present results of an entirely natural language prompt-generated agent, capable of absolving any of the 26 experiments we tested it on. Most tasks are passed with data that can pass as human osf.io/preprints/ps... (1/)

How much of a risk are LLM-generated bots for online behavioral experiments? We present results of an entirely natural language prompt-generated agent, capable of absolving any of the 26 experiments we tested it on. Most tasks are passed with data that can pass as human osf.io/preprints/ps... (1/)

The agent was built in August/September using a monthly subscription of around 17 euros/dollars. Time investment including testing on most of the tasks was about two weeks. By now, even less sophisticated prompting is sufficient to solve complex behavioral tasks in 1-2 attempts.

Christoph Strauch reposted

Now final in @elife.bsky.social: #Synesthetes really do 'see' when reporting colors while reading (typeface gray) numbers: pupils change according to the perceived colors' brightness - if a synesthete sees a bright yellow, the pupils become smaller. elifesciences.org/articles/110...

Christoph Strauch@cstrauch.bsky.social

We show that synesthesia is sensory and automatic in nature: the pupil scales with the brightness of experienced synesthetic colors. doi.org/10.7554/eLif... Now in its new dress @elife.bsky.social (convincing & valuable in round 1). If anyone wants to pick up the method, happy to share & explain!

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Finally, brightness-effects were interacting with self-reported strength. Synesthetes claimed different levels of strength (e.g. the bright blue for a 5 being stronger than the dark orange for a 3). And indeed, for those stronger couples, brightness effects on the pupil were also bigger

All this is fun for synesthesia research, but it also allows something quite decent in consciousness research: Objectively studying sensation that is generated internally alone. All scripts and stuff available online. Thanks to Casper Leenaars & Romke Rouw & the quite helpful reviewers & editor!

Now final in @elife.bsky.social: #Synesthetes really do 'see' when reporting colors while reading (typeface gray) numbers: pupils change according to the perceived colors' brightness - if a synesthete sees a bright yellow, the pupils become smaller. elifesciences.org/articles/110...

Christoph Strauch@cstrauch.bsky.social

We show that synesthesia is sensory and automatic in nature: the pupil scales with the brightness of experienced synesthetic colors. doi.org/10.7554/eLif... Now in its new dress @elife.bsky.social (convincing & valuable in round 1). If anyone wants to pick up the method, happy to share & explain!

A control group that also had to report colors after seeing the same numbers showed no such effect. Interestingly, the synesthesia-evoked pupil response was relatively fast (slower than a regular light response of course!) suggesting that colors indeed emerge automatically.

This also showed in another pupillary response: effort-linked pupil dilation was a lot bigger in controls also having to report a color per number (although not seeing one) than in the synesthetes and another control group not having to report any color. Meaning: synesthetic experience is effortless

Christoph Strauch reposted

Wooow! @danwang7.bsky.social just won the Early Career Excellence Award at the APCV/EPC 2026 meeting! As her supervisor in the past 3 yrs, I have seen so much professional & personal growth. It makes me incredibly proud that this was also seen by an independent jury on the other side of the planet.

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Averaging pupil size over five minutes gives quite similar load distinction as NASA TLX or accuracy (±100 key presses per 5 mins). If one combines all three, one gets by far the best distinction

But the pupil of course provides a continuous measure! Convolving luminance events allows to remove them from the signal, leaving a signal that much better represents effort/arousal-induced changes

New preprint (doi.org/10.64898/202...) shows that where you look next is an economic decision. Saccades trade off effort-costs (measured via pupil) against monetary rewards. 1) By default, participants have strong saccade direction preferences (e.g., cardinal over diagonal, up over down) (1/4)

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4) Costs and rewards take separable roles in selection - different mapping onto choices 5) Rewards dont speed up saccades per se - a wider utility (reward-cost) gap does. Reward can slow them too! (3/4)

New preprint (doi.org/10.64898/202...) shows that where you look next is an economic decision. Saccades trade off effort-costs (measured via pupil) against monetary rewards. 1) By default, participants have strong saccade direction preferences (e.g., cardinal over diagonal, up over down) (1/4)

2) but participants titrating payouts via ELO across direction cancel these entirely without us ever feeding in a cost map 3) Costs in Euros and pupil size are highly correlated (r=.71) (2/4)

Christoph Strauch reposted

Last piece of @ajhoogerbrugge.bsky.social PhD is finally out in @psychscience.bsky.social. Alex work very nicely shows that concurrent search is possible (people just prefer sequential search usually). What's more, people flexibly pick from these strategies

Alex J. Hoogerbrugge@ajhoogerbrugge.bsky.social

Investigations into whether we can search for multiple targets in a simultaneous fashion have led to mixed findings. In this new PsychScience article, we report that people CAN search concurrently, but don't always DO so... 🧵 journals.sagepub.com/doi/10.1177/...

Christoph Strauch reposted

Christoph Strauch reposted

Past experiences shape current selection. But when and how strong are past and present targets represented in the brain? In our newest paper, we show that past and present search targets are concurrently represented in the brain. Out now in @plosbiology.org doi.org/10.1371/jour... #neuroscience

doi.orgPast and present goals are represented concurrently during visual searchPast experience and our current goals guide what information to focus on. But how and when does the brain represent the past and the present? This new study shows that the brain represents the past an...

Christoph Strauch reposted

We have 3 PhD positions at our department (www.jobbnorge.no/nn-no/ledige...). Know a good student interested in working with me on perception / visual memory? I'd be happy to support the proposal! A catch: this person must speak a Scandinavian language as the position implies some teaching duties.

jobbnorge.noTre stipendiatstillingar ved Institutt for samfunnspsykologi (299274) | Universitetet i BergenStillingstittel: Tre stipendiatstillingar ved Institutt for samfunnspsykologi (299274), Arbeidsgivar: Universitetet i Bergen, Søknadsfrist: søndag 16. august 2026

Christoph Strauch reposted

Nothing not to love here. Some extra nerd love for the joy letting his pupil dilate at 14:32 (that is not remotely related to ours!). Maybe it's me projecting that it's joy. But you can't really stop me from that, can you?

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Package is available via github and fully open, including example data. You can use it with MNE, for instance! We see our method as useful primarily for tasks involving few and large eye movements (antisacce, memory guided saccade tasks etc.) Hopefully opens opportunities for reanalyses, too!