The Infinite Brief

When you’re browsing a website and the mouse cursor disappears, it might be a computer glitch — or it might be a deliberate test to find out who you are. The way you press, scroll and type on a phone screen or keyboard can be as unique as your fingerprints or facial features.

Some use the technology only to weed out automated attacks and suspicious transactions, but others are going significantly further, amassing tens of millions of profiles that can identify customers by how they touch, hold and tap their devices.

Using sensors in your phone or code on websites, companies can gather thousands of data points, known as “behavioral biometrics.”

For example, BioCatch builds a profile on each person’s gestures, which is then compared against the customer’s movements every time they return. The system can detect impostors with 99 percent accuracy.

A few months ago, the software picked up unusual signals coming from one wealthy customer’s account. After logging in, the visitor used the mouse’s scroll wheel — something the customer had never done before. Then the visitor typed on the numerical strip at the top of a keyboard, not the side number pad the customer typically used.

Privacy advocates view the biometric tools as potentially troubling, partly because few companies disclose to users when and how their taps and swipes are being tracked.