Q+A CENTER

Other approaches use a pressure mat, monitor-mounted sonar or a radio-frequency reader in tandem with a proximity badge system.

Pressure mats may prove impractical due to installation limitations and physical constraints. They are incompatible with wheelchairs and readily can be defeated with an inanimate object placed on the mat to indicate presence.

Sonar sensors are unable to differentiate between a person and an inert article. With a tendency toward prematurely locking the computer, they are irritating at best. At worst, like pressure mats, blocking the detector (even with a 3M Post-it) simulates user-presence and circumvents the mechanism.

Proximity badges with radio-frequency interrogation are unfeasible in settings where the operator leaves his/her computer but remains in the vicinity. A tempting target for hackers, tags suffer from poor reliability due to occlusion and electromagnetic interference. They are too easily swapped or shared.

Widespread adoption of those approaches is hampered by one significant, inherent shortcoming: even the most robust presence detection technology fails to recognize a particular person. Enter the marriage of presence detection with user identification.