Keystroke Dynamics - Temporal Variation

Temporal Variation

One of the major problems that keystroke dynamics runs into is that a person's typing varies substantially during a day and between different days. People may get tired, or angry, or have a beer, or switch computers, or move their keyboard tray to a new location, or use a virtual keyboard, or be pasting in information from another source (cut-and-paste), or from a voice-to-text converter. Even while typing, a person, for example, may be on the phone or pausing to talk. And some mornings, perhaps after a long night with little sleep and a lot of drinking, a person's typing may bear little resemblance to the way he types when he is well-rested. Extra doses of medication or missed doses could change his rhythm. There are hundreds of confounding circumstances.

Because of these variations, any system will make false-positive and false-negative errors. Some of the successful commercial products have strategies to handle these issues and have proven effective in large-scale use (thousands of users) in real-world settings and applications.