NEW YORK (CBSNewYork) — Virtual reality headsets are a hot gift this holiday season,

The headsets have been promoted as a cool, new experience, but there’s still a lot that remains unknown about the technology especially when it comes to kids.

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As CBS2’s Dr. Mallika Marshall reported, the headset completely immerses users in a new 3D virtual world.

Many of the top selling brands warn against letting kids sue the devices. Oculus Rift and Samsung VR Gear say their products aren’t for kids under 13. Sony PlayStation has recommended their for kids 12 and up. The HTC Vive was less specific, but was not recommended for young children.

“This is a big area of both interest and some concern,” Dr. Joseph Rizzo of Mass eye and Ear said.

Dr. Rizzo said the research is still out on VR.

“There’s a legitimate question about whether that much exposure to artificial visual stimuli will alter the way the brain accepts and processes visual information. It’s an unknown,” he said.

The challenge for the eyes and the brain while using virtual reality is that while the image is up close to your face it manages to trick your brain into seeing depth. It’s unknown what kinds of conflict could exist for users.

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“The immediate concerns are with the younger users because they will be prone to use them for much longer periods of time,” Dr. Rizzo explained.

Those concerns include what this might mean for a young developing brain.

“You need to understand whether the brain is changing in some permanent way,” Dr. Rizzo said.

So what should parents do?

“You should encourage judicious use of these devices, perhaps with time periods limited to 30 minutes or so,” Dr. Rizzo said.

It remains to be seen when research will catch up with technology.

“Well, there’s a lot of research that needs to be done, and it should be done quickly. The devices are available and there is going to be an explosion in their availability in the next years. It’s happening,” Dr. Rizzo said.

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The headsets cost between $30 and $800.