Privacy Policy — Colori & Colympics

1 Data Controller

The responsible researcher for the Colori and Colympics apps is:

Prof. Dr. Karl R. Gegenfurtner

Abteilung Allgemeine Psychologie
Justus-Liebig-Universität Gießen
Otto-Behaghel-Strasse 10F
35394 Gießen, Germany

Email: gegenfurtner@uni-giessen.de

The institutional data protection officer of Justus-Liebig-Universität Gießen can be reached at:

Der Behördliche Datenschutzbeauftragte

Justus-Liebig-Universität Gießen
Ludwigstraße 23
35390 Gießen, Germany

Email: datenschutz@uni-giessen.de
Phone: +49 641 99-12230 or +49 641 99-12270

2 What We Collect

The app distinguishes between data stored locally on your device (always) and data uploaded to our server (only if you give consent — via the consent dialog shown at app start, the upload prompt at the end of a game, or the online-sharing toggle in the Highscores screen).

Only substantial game sessions are uploaded. A session is transmitted only if you played past round 21 and did not quit the game manually. Shorter or abandoned games are never sent to the server. Sessions played before you gave consent are never uploaded retroactively.

Data	Always local?	Uploaded if opted in?	Notes
Install ID	Yes	Yes	Random UUID generated on first launch. Not linked to your Apple ID, Google account, or any other account.
Nickname	Yes	Yes	Self-chosen name for the highscore list. Can be left empty or use a pseudonym.
Game scores	Yes	Yes	Total score, accuracy %, and axis sensitivity scores (RG, BY, BW).
Trial-by-trial response data (CSV)	Yes	Yes	Per-disc: color (RGB), ΔE distance, whether tapped, reaction time (ms), reward/penalty. This is the primary scientific data.
Device model	No	Yes	E.g. "iPhone 16 Pro" or "Pixel 9". Used to understand display characteristics.
Operating-system version	No	Yes	E.g. "iOS 18.3" or "Android 15". For compatibility analysis.
Display gamut & bit depth	No	Yes	Whether your screen is wide-gamut (P3) and supports 10-bit rendering — critical metadata for color science.
Screen brightness	No	Yes	Recorded at session start and end (on Android additionally the ambient-light sensor reading). Used as a proxy for ambient light conditions, which affect color perception.
Session timestamp	No	Yes	ISO-8601 date and time of the game session (your local timezone).
App variant	No	Yes	"colori", "colympics", or "colorlab". For segmenting research data.
Game settings	No	Yes	Layout mode, difficulty, color mode. Included in the CSV metadata header.

No location, no contacts, no camera, no microphone. The app requests no system permissions beyond the network (for uploading, if opted in). We do not collect your name, email address, Apple ID, Google account, or any other personally identifying information. When your device contacts our server, its IP address is processed transiently in the university web server's access logs (as with any website); it is never stored with or linked to research data.

3 Why We Collect It

We collect data for two distinct purposes:

App functionality (local only): Your install ID, nickname, and scores are stored on your device to maintain local highscores and personal game history across sessions. This data never leaves your device unless you enable online sharing.

Scientific research (uploaded if opted in): The primary purpose of the app is psychophysical research into human color discrimination. Your trial-by-trial response data — which colors you detected, which you missed, and how quickly you responded — are invaluable scientific measurements. Aggregated across many participants, they allow us to construct a three-dimensional map of human color discrimination thresholds, as described in our preprint (doi: 10.64898/2026.03.09.710376).

Global highscores: If you opt in, your nickname and score are also displayed in a global leaderboard within the app. You can disable this at any time from the Highscores screen.

4 Legal Basis (GDPR Article 6)

Local storage of scores and preferences is necessary for the app to function (Art. 6(1)(b) — performance of a contract / provision of the requested service).

Uploading data to our server relies on your freely given, informed consent (Art. 6(1)(a)). Consent is requested via a consent dialog shown at each app start until consent is given; once given, it is saved and can be withdrawn at any time via the online-sharing toggle in the Highscores screen. Consent can also be given via the upload prompt shown at the end of a qualifying game. After withdrawal no further uploads occur. Previously uploaded data are retained as anonymized research records (see Retention below).

This research protocol has been approved by the ethics committee of Justus-Liebig-Universität Gießen (approval number LEK-2026-0039).

5 Data Sharing

Uploaded data are stored on a server operated by Justus-Liebig-Universität Gießen (Germany) at the URL https://www.allpsych.uni-giessen.de/karl/colympics/api/. This server is located within the European Union and is subject to German data protection law.

We do not sell, rent, license, or share your data with any third party for commercial purposes. Research data may be shared with scientific collaborators (universities, research institutions) for the purposes of peer-reviewed publication, in anonymized form.

Uploaded CSV files contain no nickname: they are stored under a name composed only of the app variant, upload timestamp, install ID, and a random suffix. Your nickname appears solely in the highscore list. No external analytics services (Google Analytics, Firebase, Mixpanel, etc.) are used.

6 Data Retention

Local data (scores, preferences, install ID, nickname) remains on your device until you delete the app. Uninstalling the app removes all locally stored data.

Uploaded research data (CSV files and scores) are retained for the duration of the research project, typically up to 10 years from the date of collection, in accordance with good scientific practice guidelines (DFG Leitlinien zur Sicherung guter wissenschaftlicher Praxis and the corresponding statutes of Justus-Liebig-Universität Gießen).

After the research project concludes, data will be either deleted or archived in anonymized form in a certified research data repository.

Uploaded data are fully anonymous: they contain no name, email address, account, or device identifier from which your identity could be recovered. For this reason individual records cannot be attributed to a specific person after upload.

7 Security

All data transmitted from the app to our server uses HTTPS (TLS 1.2+) encryption. Data uploads include a shared API key to prevent unauthorized submissions. The server is maintained by IT services at Justus-Liebig-Universität Gießen under institutional security policies.

Because the data we collect is not highly sensitive (no financial, health, or location data), the risk to individuals from any data breach is considered low. Nevertheless, we take reasonable technical and organizational measures to protect stored data.

8 Your Rights Under GDPR

If you are located in the European Economic Area, you have the following rights regarding your personal data:

In practice, most of these rights are already fulfilled by design. The data uploaded to our server are anonymous — we cannot attribute any record to you, so there is nothing we could hand over, correct, or delete for a specific person. The complete data about your games (including everything ever uploaded) is stored on your own device, in a folder you can access directly, and is deleted when you uninstall the app.

Right of access (Art. 15): You may request a copy of all personal data we hold about you.
Right to rectification (Art. 16): You may request correction of inaccurate data (e.g. your nickname).
Right to erasure (Art. 17): Highscore entries (nickname and score) can be deleted on request. Uploaded research files contain no nickname and cannot be attributed to a person; where attribution is impossible, erasure requests cannot be fulfilled for specific records (Art. 11).
Right to data portability (Art. 20): You may request your data in machine-readable format (CSV, as it is already stored).
Right to withdraw consent (Art. 7(3)): You can withdraw your consent to data upload at any time by toggling off online sharing in the app. This does not affect the lawfulness of processing before withdrawal.
Right to lodge a complaint: You may lodge a complaint with the supervisory authority in your country of residence. In Germany: Hessischer Beauftragter für Datenschutz und Informationsfreiheit (HBDI), Postfach 3163, 65021 Wiesbaden.

To exercise any of these rights, contact us at the address in §11.

9 Children

The apps contain no content inappropriate for children (rated 4+ on the Apple App Store and the equivalent on Google Play). We do not knowingly collect personal data from children under the age of 16 without verifiable parental consent. The online-sharing feature is disabled by default, so no data is uploaded unless a user actively agrees.

If you believe a child under 16 has uploaded data without parental consent, please contact us: we can remove the corresponding highscore entry (identified by nickname and date). Uploaded research files contain no name or nickname and cannot be attributed to an individual.

10 Changes to This Policy

We may update this Privacy Policy as the app evolves or as legal requirements change. Material changes will be noted in the app's release notes and on this page with an updated "last updated" date. Continued use of the app after a policy change constitutes acceptance of the revised terms.

The current version is always available at https://www.allpsych.uni-giessen.de/karl/colympics/privacy.html.

11 Contact

For any questions, rights requests, or concerns about this Privacy Policy or the data we process, please contact:

Prof. Dr. Karl R. Gegenfurtner

Abteilung Allgemeine Psychologie
Justus-Liebig-Universität Gießen
Otto-Behaghel-Strasse 10F, 35394 Gießen, Germany

Email: gegenfurtner@uni-giessen.de