Interaxon has trained its model on about 50,000 hours of EEG from Muse users, stripped of names and emails, and plans to use "as much of that eligible corpus as possible." Its privacy policy did not say so. After Science pointed it out, the company changed the policy. "We agree users should be explicitly informed," said its chief marketing officer.

Every element comes from the company's own mouth, including the admission. The policy change is the article's strongest piece of evidence, because a company does not revise a document it believes was already adequate.

"Without telling users" means without telling them in the privacy policy. Science notes the foundation model efforts were disclosed elsewhere, in press releases. That is a weak form of notice, and it is still notice. The headline's "harvesting" is fair for the scale and unfair for the tone; the data were collected for a service users wanted and then reused.

Of 57 companies, four had no policy and 11 covered only website visitors. Almost all allow deidentified sharing with third parties, only six rule out selling brain data, and none rule out handing data to authorities.

The pattern matches an independent 2024 Neurorights Foundation review of 30 companies, which found that 29 placed no meaningful limits on how they used or sold user data and fewer than half encrypted and deidentified it. Two reviews, two years apart, same picture.

The 57 companies are not named, the coding rules are not published, and "about two thirds" leaves the denominator to the reader (roughly 42 companies with a full policy, by subtraction). Silence on police requests is standard boilerplate across consumer tech and says more about lawyers than about neurotech.

Nine consumer neurotech and AI software companies have publicly acknowledged building one. None of the consumer device makers among them disclosed it in their privacy policies. Emotiv trains its "large brain model" partly on data from its higher end devices and, after Science's inquiries, now requires opt in consent.

The Emotiv account is specific and confirmed by the company. Emotiv has history here. In August 2023 the Chilean Supreme Court ordered it to delete a former senator's brain data collected without adequate consent.

Only three of the nine are named. Readers cannot check the other six.

Consumer headsets use one to six electrodes against 19 to 25 on a clinical cap, cover a small patch of scalp, and see little of the deep structures that handle emotion and memory. Some experts say this limits what can be learned to broad states such as sleep onset. Rafael Yuste says AI analysis of surface signals could be enough to decode "thoughts, emotions, and personality."

The hardware description is accurate, and the article gives the skeptics real space. A venture investor calls an all purpose brain model "a very, very long way off." Nita Farahany points out that clicks and eye tracking already reveal as much about mental states as a forehead sensor.

The decoding claim is a forecast, and Yuste cofounded the Neurorights Foundation, which campaigns on exactly this issue. So does Jared Genser, its general counsel, also quoted. Their views are legitimate. They are also the advocacy side of the story, and the article does not label them that way.

A 2018 study found that of more than 3,000 publications cited by consumer EEG companies, only 11 used gold standard methods, and 10 of those found no benefit over a control.

Wexler and Thibault reviewed 18 consumer EEG companies. The 3,000 figure is the body of neurofeedback literature claiming benefits for attention, cognition and insomnia, which the companies lean on. Eleven of those experiments were double blind with a sham control, and ten found sham and real neurofeedback equivalent. Only one of the 18 devices had been validated against research grade EEG.

"Cited by these companies" slightly overstates it; the companies point to a literature, not a bibliography of 3,000 papers. The paper's sharper finding, that 17 of 18 devices had no public validation at all, did not make the article.

Piramidal, trained on more than 4 million hours of public and hospital EEG, fine tuned its model on Cleveland Clinic data and correctly identified nine of ten seizures in a pilot.

Ten events is an anecdote with a denominator. No false alarm rate, no comparison with existing seizure detection software, no publication. Clinicians judge seizure detectors by how often they cry wolf, and that number is absent.

The more consequential thread is consent. Piramidal draws on open research corpora such as Temple University's EEG Corpus (60,000 recordings). Patients consented to research, and Farahany notes they did not contemplate AI training. The CEO's answer, that these patients are "waiting for something to be built like that," is an argument about what patients would want, offered by the person who benefits from the answer.

Chile protected brain data in its constitution in 2021 and its Supreme Court ruled against Emotiv in 2023. Colorado and California have added neural data to state privacy laws. A bill from Senator Schumer would have the FTC study gaps and propose a framework.

Accurate. Colorado amended its law in April 2024 and California in September 2024, and Montana and Connecticut followed in 2025. The federal bill is the MIND Act, introduced in September 2025 by Senators Cantwell, Schumer and Markey.

The MIND Act directs a study. It regulates nothing. And HIPAA, which governs the same EEG in a hospital, does not reach a headband bought online.

The neurotechnology market is worth about $19.19 billion this year and should reach nearly $33 billion by 2034. Apple has patented EEG earbuds and Meta sells a Neural Band.

The figure is an unsourced market research estimate, and "neurotechnology" in those reports usually includes implants, neurostimulators and hospital equipment. The consumer headband slice is a fraction. A patent is not a product. The Meta band reads muscle signals at the wrist. It counts as neural data under California's definition, which covers peripheral nerves, but it is not reading anyone's brain.