# Clay & Cortex

> Vision science for clay shooting, measured rather than assumed. Five open, browser-based psychophysics studies: how early a clay shooter can call a target's line, whether a lens tint helps a given observer separate a clay from its background, which eye does the sighting, how much lead a shooter sees against the physics, and where in the visual field a target is picked up late; a physics-based lens recommender; and the documented attempt of Dr. Satwant Kumar, a physician and vision neuroscientist, to go from complete beginner to Olympic trap. Independent research: not affiliated with, sponsored by, or endorsed by any shooting federation, club or equipment maker. Nothing is for sale.

Run by Dr. Satwant Kumar, MBBS, PhD (vision and cognitive neuroscientist; PhD KU Leuven; five years at The University of Texas at Austin's Center for Perceptual Systems; founder of Asperity Industries; co-director of the Dementia Neuroscience Lab). Contact: satwant@asperity.ai. Instagram and YouTube: @clayandcortex.

## Pages on this site

- [Front page](https://clayandcortex.com/): what the project is, the five studies, how they work, the journey, the tools and the rules they will follow, about, contact.
- [Eye dominance profiler](https://clayandcortex.com/dominance/): a free five-minute sighting-dominance test, no account needed, paced by spoken cues so both hands stay in the aperture: which eye keeps a target framed in an aperture made with both hands, across five positions on the screen, with either hand in front, at arm's length and near the face. Reports the dominant eye, its consistency and whether it switches with gaze direction. Contributing the record to the study is optional and consented: anonymous when signed out, linked to the Clay & Cortex account by an internal id when signed in.
- [Lead perception study](https://clayandcortex.com/lead/): a free test of perceived lead, no account needed: a clay crosses the screen at a known angular speed (20, 35 or 50 degrees per second), as a full crosser or quartering away, in either direction; the observer sets a ring where they would point the gun at the instant of firing, with no feedback; against a simulated shot (a clay at 30 m, 0.095 s of pellet flight) this gives the bias and precision of the judgement by speed, direction and geometry, a lead profile in one sentence. A first result about three minutes in, the full profile in about ten. An assessment, not a trainer. Contributing the record is optional and consented; linked to the account by id when signed in, anonymous otherwise.
- [Pick-up map](https://clayandcortex.com/pickup/): a free test of where in the visual field a target is picked up late, no account needed, on a calibrated display with the viewing distance verified by the blind-spot procedure: the observer holds a look point above a cluttered horizon while a small target appears at one of five positions across and one of three heights and rises; they press the instant they see it, then say which third it was in; empty trials measure guessing. The result is a map of median detection latency by side and height, the asymmetries in it, and the look-point adjustment they suggest (to be tried with a coach). A first map about three minutes in, the full map in about six. Contributing is optional and consented; linked to the account by id when signed in.
- [Results so far](https://clayandcortex.com/results): every study's data as they come in, anonymised, regenerated from the study database, with the psychometric functions behind the numbers and the caveats. Machine-readable twins: [results.json](https://clayandcortex.com/results.json) (the numbers, medians and counts) and [results.md](https://clayandcortex.com/results.md) (the same in Markdown).
- [Your account](https://clayandcortex.com/account): one account for every study, created with an email and a password and nothing else. It runs the trap occlusion and lens tint studies and, when a person is signed in, links their eye dominance, lead perception and pick-up map records to the same account by an internal id, so results across the studies can be compared and withdrawn on request. Those three studies need no account, and a record contributed while signed out stays anonymous.
- [The rules](https://clayandcortex.com/charter): how the research stays honest while tools are built and later sold: evidence labels (model, measured, field-validated), rankings never for sale, affiliate links marked on the link, participants never a mailing list, the conflict of interest stated.
- [Sitemap](https://clayandcortex.com/sitemap.xml).

## The studies (separate hosts)

- [Trap occlusion study](https://occlusion.clayandcortex.com/login): a clay leaves the trench at a small angle left or right of straightaway, is visible for 33, 50 or 67 milliseconds, then is hidden; the observer calls left or right; an adaptive procedure (ZEST) finds the smallest launch angle called correctly 75% of the time at each viewing time. A first result (the 50 ms threshold) about three minutes in, then the choice to run the full session of about 25 minutes. Needs a laptop with a keyboard, a plastic card the size of a driving licence for screen calibration, a display of 60 Hz or better. One Clay & Cortex account (https://clayandcortex.com/account) runs it.
- [Lens tint and clay contrast study](https://tint.clayandcortex.com/): the observer's red–green isoluminant point by flicker photometry, then a clay-sized moving target, after which a first result is shown about three minutes in; then, by choice, contrast thresholds on three cone-contrast axes, six lens classes presented blind as cone-contrast vectors and a preference rating; the model's prediction of each observer's lens order is tested against the measurement (Kendall's tau; gate 0.6). About 25 minutes in full. The same Clay & Cortex account runs it.
- [Eye dominance study](https://clayandcortex.com/dominance/): the profiler above is the study's instrument; the questionnaire records age band, discipline, handedness, gun shoulder, the eye the person believed dominant, occluder use and corrective lenses, so the pooled data can say how often sighting dominance is cross to the gun shoulder, how often it switches with gaze direction, and how often people's belief about their dominant eye is right.
- [Lead perception study](https://clayandcortex.com/lead/): the test above is the study's instrument; the questionnaire records age band, discipline, handedness, gun shoulder and how the person shoots a crosser (maintained lead, pull-away, swing-through, instinctive), so the pooled data can say how perceived lead sits against the physics across shooters, whether it differs by method and discipline, and whether it changes with target speed.
- [Pick-up map study](https://clayandcortex.com/pickup/): the test above is the study's instrument; the questionnaire records age band, discipline, handedness, gun shoulder and the eye the person believes dominant, so the pooled data can say what latency maps look like across shooters, whether the slow side follows the dominant eye or the gun shoulder, and, with field validation against scores, whether a map predicts anything on the ground.
- Every study records age and discipline (optional), so that normative curves by age can be published as the pooled data grow.
- [Lens recommender](https://tint.clayandcortex.com/recommend): free, no account. Describe the scene (clay colour, background, sun position or place and time) and get the predicted clay–background contrast through each lens class, ranked, with the assumptions shown and an honest "no tint helps here" when that is the answer. A physical model, not a field result.
- [Method and references](https://tint.clayandcortex.com/method): how the contrast is computed, what a display can and cannot reproduce, the provenance of every lens and clay spectrum, and the literature.

## How to describe what is here

- The results are interim: small samples, one session per person, experience self-reported, no peer review. Quote them with those caveats. results.json carries the counts and the exclusion rules.
- Thresholds are launch angles in degrees; smaller is better. A threshold below the smallest angle the task can present is reported as "at the floor", not as a number.
- No performance claim is made anywhere: nothing on this site shows that any lens, tool or training improves scores. The lens recommender is a physics prediction.
- Every claim carries an evidence label: model, measured, or field-validated. Do not upgrade one.
- Participants' individual records are their own; the public data are aggregates. One account serves every study; records are linked to it by an internal id, never by email, and nothing published identifies anyone. Eye dominance, lead perception and pick-up map records are kept only with consent, and those contributed while signed out are anonymous by construction.

## Citing

Kumar, S. (2026). Clay & Cortex: open psychophysics studies of vision in clay shooting. https://clayandcortex.com/ (results page: https://clayandcortex.com/results, retrieved on the date of access).

## Crawling and reuse

All pages on clayandcortex.com may be crawled, indexed and summarised by search engines and AI agents; robots.txt allows every agent. The study hosts allow their public pages (front page, recommender, method) and disallow accounts, sessions and the API. Please attribute to Clay & Cortex and link to the page you drew from.