If your kids are asking for a virtual reality headset this holiday season, you might be interested in this guide from Common Sense Media. It covers everything from Google's inexpensive Cardboard VR viewer to Sony's new PlayStation VR. The guide mentions the headsets have minimum age requirements set by the manufacturers that you should check before you buy – generally ages 12 and up. This is important to keep in mind because, as many are pointing out, there is little research about the effect virtual reality has on very young children. Concerns include psychological development, effects on the eyes, and problems distinguishing reality from fiction or fantasy, which young children already have difficulty doing and is exaggerated even more in virtual reality.