Given the volume of reporting on the data security risks posed by hackers and other bad actors online, it can be easy to overlook the "visual privacy" risks we encounter every day in the real world.
As any "perpetually curious" person can tell you, there is a wealth of information available from even a brief look at the phone screen of someone sitting next to you at a coffee shop. To see the scope of the problem, just look around. For example, two women recently filed wiretapping and invasion of privacy claims against a casino in Pittsburgh, alleging that the casino used its video surveillance systems to record texts, emails, and banking information displayed on their smartphones for use in an ongoing child custody dispute.
Fortunately, there is an easy way to protect yourself from the wandering eyes of the perpetually curious. Privacy screens – essentially, polarized filters that only permit someone directly in front of the device to see the screen's content – are relatively cheap, readily available for both smartphones and laptops, and easy to install. A quick search for "privacy filters" on Amazon yielded more than 3,000 results, so you can certainly find one customized to fit your device.
While perpetual curiosity is something to strive for in life, it is also something to guard against in practice. As always, stay vigilant.