Clay & Cortex

Vision science for clay shooting

What a clay shooter's eyes are doing, measured rather than assumed.

Clay & Cortex runs open, browser-based psychophysics studies on the visual questions clay shooters argue about: how early you can call a target's line, and whether a lens tint helps your eyes separate a clay from its background. Each study calibrates your screen, states in advance what result would count, and gives you your own data.

It is also a lab notebook: a physician and neuroscientist who took up Olympic-style trap shooting in 2026, as a complete beginner, is documenting the attempt with every rep measured and every miss logged.

Take part in a study Follow the journey

Two studies, one instrument

Both studies share the same calibration, timing and adaptive-estimation code. They differ in the question. Each runs in a normal browser on a laptop with a keyboard; each needs a bank card to calibrate the screen and about half an hour.

Study 1 · ISSF trap · open

Trap occlusion study

How early can you call the line of a trap target?

A clay is launched from the trench at a small angle left or right of straightaway, is visible for between 33 and 100 milliseconds, and is then occluded. You report left or right. An adaptive procedure finds the smallest angle you can call at each viewing time, so the result is a curve of angular threshold against visible flight, not a score.

Four viewing durations, fully interleaved; 334 trials including practice and lapse probes; about 30 minutes.

Open to anyone: create an account with an email and a password. Trap shooters at any level, and non-shooters as a comparison group.

Run the study

Study 2 · all disciplines · open

Lens tint and clay contrast study

Which lens tint separates a clay from its background, for your eyes, on your field?

A tinted lens cannot add light. It can only remove light differently from the clay and from what is behind it, and whether that helps depends on the clay's pigment, the background, where the sun is, and how sensitive your own eyes are to the brightness and colour differences that result. This study measures the last of those and tests whether a physical model predicts which lens classes work for you.

Your red–green isoluminant point by flicker photometry; contrast thresholds on three cone-contrast axes; a clay-sized moving target; six lens conditions presented blind; a preference rating. About 25 minutes. You get your profile at the end.

Open to anyone: create an account with an email and a password.

Run the study Also: lens recommender · method and references

The journey

The lab notebook

From beginner to the Olympic trap line, documented

In the summer of 2026, at 38, Satwant took up Olympic-style trap shooting as a complete beginner, with one question: how far can science, data and 25,000 targets a year take someone who starts from zero? The stated target is the 2032 Olympic Games. The probability, in his own words, is low. The point is the record: every rep measured, every miss logged, every method tested, so that whatever the outcome, the attempt is documented properly.

The studies on this site are part of that notebook. The rest of it, week by week, is on Instagram and YouTube.

Instagram YouTube

How the studies work

Your screen is calibrated, not assumed

Screen scale from matching a bank card (ISO/IEC 7810 ID-1); viewing distance by the blind-spot method (Li, Joo, Yeatman & Reinecke 2020), cross-checked against what you report; refresh rate measured. Every stimulus is specified in degrees of visual angle and shown for a whole number of frames, and a dropped frame rejects the trial.

Thresholds, not scores

Adaptive Bayesian placement (ZEST; King-Smith et al. 1994) puts each trial where it tells the most. Thresholds are fitted by maximum likelihood with bootstrap confidence intervals, and a threshold outside the range actually tested is reported as not measurable rather than as a number.

Gates stated in advance

Each study says, before the data come in, what result would justify the next step: test–retest reliability before any individual claim, model-against-measurement agreement before a personal recommendation, and a field study with real equipment before any claim about performance.

Your data are yours

At the end of a session you can download the complete record: the configuration, the random seed, your calibration, and every stimulus and response. The server keeps the same file. No name is asked for; your email is used to sign in and for nothing else.

Screening, not diagnosis

The colour-vision task in the tint study runs on a display whose colour is assumed, not measured. A flag from it means "see an optometrist", nothing more, and no result here is a clinical finding.

Independent

No lens or equipment maker is involved in either study. Lens names appear because people shop by name; the ranking is computed from the physics of the lens, the clay and the light, and inclusion is not endorsement. Any commercial link on this site is labelled as one. The rules.

Tools, and the rules they will follow

In development

Training tools and a simulator

The studies exist to answer questions; the tools will be what those answers make possible: a personal visual profile, a lens recommendation that uses it, and a simulator for the parts of trap that can be trained off the range. Nothing is for sale yet. When something is, it will appear here with the evidence behind it.

Until then, the lens recommender is free and will stay free.

Kept honest

Research on one side, products on the other

The person running these studies will also sell tools built on them, and the site says so. The rules that keep that honest are written down before there is anything to sell: every product carries an evidence label (model, measured, or field-validated), no ranking is ever for sale, every affiliate link is marked, study participants are never a mailing list, and negative results are published.

Read the rules

About

Satwant Kumar

Satwant Kumar, MBBS, PhD

Vision and cognitive neuroscientist, trained as a medical doctor.

Satwant is a physician-scientist who studies how the brain sees. He trained as a physician (MBBS, the equivalent of an MD), earned his PhD in neuroscience at KU Leuven in Belgium, and spent five years as a postdoctoral fellow at The University of Texas at Austin's Center for Perceptual Systems, where he developed optical tools to record and control neural activity in the visual cortex. His work on how the brain identifies bodies and separates objects from their backgrounds has appeared in PNAS, eLife, Cerebral Cortex and the Journal of Cognitive Neuroscience.

Today he is the founder of Asperity Industries, an AI robotics company in Tyler, Texas, and co-director of the Dementia Neuroscience Lab, where he works on brain imaging and clinical AI for Alzheimer's disease. He previously founded NeuroReef Labs, a healthcare AI startup backed by Antler, and serves as volunteer Chief Scientific Officer of the Alzheimer's Alliance of Smith County and as volunteer faculty in neurology at The University of Texas at Tyler.

Since 2026 he has also been a trap shooter in training. Clay & Cortex applies those laboratory methods to clay shooting, starting with his own.

Instagram · YouTube · LinkedIn · ORCID · Publications

Selected publications

  1. Yilmaz, H., Shah, A. D., Letrou, A., Kumar, S., Vogels, R. & Yildirim, I. (2025). Multiarea processing in body patches of the primate inferotemporal cortex implements inverse graphics. Proceedings of the National Academy of Sciences, 122(28), e2420287122. doi:10.1073/pnas.2420287122
  2. Chen, C. Y., Chen, Y. Y., Benvenuti, G., Kumar, S., Ramakrishnan, C., Deisseroth, K., Geisler, W. S. & Seidemann, E. (2022). Similar neural and perceptual masking effects of low-power optogenetic stimulation in primate V1. eLife, 11, e68393. doi:10.7554/eLife.68393
  3. Kumar, S., Mergen, E. & Vogels, R. (2022). It is not just the category: behavioral effects of fMRI-guided electrical microstimulation result from a complex interplay of factors. Cerebral Cortex Communications, 3(1), tgac010. doi:10.1093/texcom/tgac010
  4. Kumar, S. & Vogels, R. (2019). Body patches in inferior temporal cortex encode categories with different temporal dynamics. Journal of Cognitive Neuroscience, 31(11), 1699–1709. doi:10.1162/jocn_a_01444
  5. Kumar, S., Popivanov, I. D. & Vogels, R. (2019). Transformation of visual representations across ventral stream body-selective patches. Cerebral Cortex, 29(1), 215–229. doi:10.1093/cercor/bhx320
  6. Kalfas, I., Kumar, S. & Vogels, R. (2017). Shape selectivity of middle superior temporal sulcus body patch neurons. eNeuro, 4(3). doi:10.1523/ENEURO.0113-17.2017

Taking part, and contact

What taking part means

Participation is voluntary and you can stop at any time by closing the page; nothing is uploaded until a session ends. Each study records your responses, the stimulus that produced each one, your questionnaire answers and your screen calibration, under the participant code you choose. The results are used for research on visual performance in clay shooting and may be published in aggregate; no individual is identifiable in what is published.

To withdraw a session or have your account removed, write to the address here with the email you registered with.

Contact

Questions about a study, a result, or a collaboration:
satwant@asperity.ai

Clay & Cortex is an independent research project of Satwant Kumar. It is not affiliated with, sponsored by, or endorsed by any shooting federation, club, or equipment maker.