Scanner Sees Guns, Misses Knives AI scanner didn't detect a knife used in school attack.

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Scanner Sees Guns, Misses Knives: AI scanner didn't detect a knife used in school attack.

An automated security-screening system failed to detect a weapon that went on to be used in an attack.

What’s new: Administrators at Proctor High School in Utica, New York, decommissioned an AI-powered weapon detector by Evolv Technologies after a student snuck a knife into the school, BBC reported. The school installed the system in 2022 for $3.7 million.

How it works: Evolv’s system uses ultra low-frequency radio sensors mounted in pillars to scan visitors at a building’s entrance. The AI model was trained on roughly 50,000 scans to classify objects including guns, knives, and bombs. The system can screen 3,600 people per hour, purportedly 10 times the rate of a walk-through metal detector. The company’s customers include museums, theme parks, stadiums, and schools.

The incident: On October 31, 2022, a student carried a hunting knife through Evolv’s scanner. Later that day, the student attacked a fellow student, who sustained serious stab wounds.

  • Following the attack, Proctor High School’s district conducted an internal investigation and found that Evolv had failed to detect knives on three earlier occasions.
  • Proctor High School replaced Evolv’s system with traditional metal detectors. Twelve other schools in the district continue to use the system. District leaders said replacing them would be prohibitively expensive.
  • In 2021, the U.S. National Center for Spectator Sports Safety and Security tested Evolv’s technology and found that it detected guns 100 percent of the time and knives 42 percent of the time.

Why it matters: Although no AI system can be expected to function perfectly all the time, systems that perform critical tasks like detecting weapons must meet a very high bar. The manufacturer has a responsibility to perform rigorous tests of the system’s effectiveness and distribute the results to prospective and actual customers.

We’re thinking: Our hearts go out to the community and family of the student who was injured. We hope that such systems will improve, and beyond that, we hope society evolves to a point where screening for weapons is unnecessary. It’s a travesty that children in the U.S., unlike most countries, live in fear of a violent attack on their schools. $3.7 million could go a long way toward paying for books, equipment, and teacher salaries.


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