The App Privacy Policy

For the Mastering the Mind app

Effective date: July 2, 2026

In short: Mastering the Mind is built to keep your practice private. Your written entries and voice recordings stay on your device. We do not run accounts, we do not operate servers that receive your content, and we do not sell or share your personal information.

1. Who we are

Mastering the Mind is published by Jeffrey Miller, Ed.D., under Deep Thinker Lab. This policy explains how the app handles your information. If you have any questions about it, contact us at me@drjeffmiller.com.

2. Information the app does not collect

The app does not require an account, a login, or any registration. We do not collect your name, email address, location, contacts, or advertising identifiers. The app contains no third-party advertising, no analytics services, and no tracking technologies. We do not receive, store, or have access to the content you create in the app.

3. Information stored on your device

Everything you produce while practicing is saved locally on your device, using the operating system’s on-device storage, and remains under your control. This includes:

Your written responses to writing, questioning, and reflection exercises.
Voice recordings you make during the Speaking Test, and any transcripts generated from them.
Predictions, outcomes, and calibration notes from the Calibration Log.
Your practice history, streaks, weekly goals, self-assessment ratings, and reminder settings.

Because this information is stored only on your device and is not transmitted to us, we cannot see it, retrieve it, or recover it on your behalf.

4. Microphone

The Speaking Test lets you record yourself explaining an idea. The app requests microphone access only for this purpose, and only when you choose to record. Recordings are saved on your device for you to review and are not sent to us or to any third party.

5. Speech transcription

If you turn on transcription for a Speaking Test recording, the app converts your speech to text using your device’s built-in, on-device speech recognition. The audio used for transcription is processed on your device and is not sent to us. If a future version of the app offers a transcription option that relies on an external service, we will update this policy and the app’s App Store privacy details before making it available, and it will be clearly optional.

6. Notifications

With your permission, the app schedules local notifications on your device to remind you to practice and to prompt you when a Calibration Log prediction is due for review. These reminders are scheduled and delivered on your device. You can turn them off at any time in the app or in your device settings.

7. Links to other services

The app’s About screen links out to external destinations, including the Deep Thinker Lab newsletter on Substack and a page where you can learn about or buy the book. When you follow one of these links, you leave the app and are subject to the privacy practices of that service. If you subscribe to the newsletter, you provide your email address directly to the newsletter provider, not to the app. We encourage you to review the privacy policies of any service you visit.

8. Children’s privacy

The app is intended for a general, adult audience and is not directed to children. We do not knowingly collect personal information from children, and, as described above, the app does not collect personal information from anyone.

9. Retaining and deleting your information

Your entries and recordings remain on your device until you delete them within the app or delete the app itself. Removing the app from your device deletes the practice data stored locally by the app. Because we never receive this data, there is nothing for you to request from us in order to have it erased.

10. Security

Your information is protected by the security of your own device, including any passcode, Face ID, Touch ID, or encryption you have enabled. We recommend keeping your device software up to date and protected with a passcode.

11. Your rights

Depending on where you live, you may have rights under laws such as the General Data Protection Regulation (GDPR) or the California Consumer Privacy Act (CCPA), including the right to access, correct, or delete personal information a company holds about you. Because the app does not collect or store your personal information on our systems, we do not hold data to provide, change, or delete. If you have any questions about your rights, contact us at me@drjeffmiller.com.

12. Changes to this policy

We may update this policy as the app evolves, for example if we add features that change how information is handled. When we do, we will revise the effective date above and, where appropriate, note the change in the app. Continued use of the app after an update means you accept the revised policy.

13. Contact

For any question or request regarding this policy or your privacy, contact:
Jeffrey Miller, Ed.D. · Deep Thinker Lab
me@drjeffmiller.com