Airline travelers are quite used to metal detectors and x-ray machines by now. And they may be getting used to what I call “the puffing thing,” but is referred to as a trace portal machine by the TSA. (That’s the device that you walk into, and it puffs air at you, analyzes bits of debris it has dislodged, and lets you go on your merry way.) Travelers are probably not yet used to the millimeter wave scanner, which I experienced over the weekend in DC.
For the uninitiated, the millimeter wave scanner is essentially radar for your body, and it allows the government to see through your clothes. Supposedly, if you don’t want to let them do that, you’re supposed to be able to say, “No, I’d rather you pat me down instead, thank you,” and there’s supposed to be a sign saying so:
In my experience, though, I didn’t see that sign. I could have been distracted, though, and I just wanted to come home. So whatever, I went into the thing, and someone somewhere got to look at me through my clothes. Hope they had a good time. I did think that the machine, apart from being irritating and an invasion, had some flaws. For one thing, at the end of the scan (which did go quickly) they asked me to put my arms out in front of me. The problem with that, though, was that my hands would extend outside the machine. Not sure if it matters, but it led to awkward movements.
Anyway, this post is titled “Biometrics and the TSA,” not “Adventures with MMW.” This is because, in addition to the puffing thing (which costs about $160,000 a device, and which apparently don’t work very well) and the MMW scanner (which costs about $120,000), CNN is reporting on a brand new way of screening passengers: The Wii Fit.
“Researchers took a Wii balance board — a device people stand on to interact with certain Nintendo Wii video games — and altered it to show how someone’s weight shifts. Studies are now under way to determine whether there is a level of fidgeting that would suggest the need for secondary screening.”
There’s a reason why polygraphs aren’t generally admissible as evidence in trial, and that is because biometric data is unreliable to interpret. See, e.g., Frye v. United States, 293 F. 1013, 1014 (D.C. Cir. 1923) (“the systolic blood pressure deception test has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made.”) Frye isn’t the best case to cite, however, as it has been overturned, questioned, and superseded on a variety of grounds, and it is true that polygraphs and other technologies (such as the plethysmograph) are used in other aspects of prosecution (such as supervised release and the like). Nonetheless, it states pretty clearly the problem of using the body’s biometric functions to determine guilt or innocence.
All in all, biometric interpreters are dicey things to start implementing at airports, where stress levels are undeniably higher than in the controlled environment of a trained polygrapher’s office. How accurate will the Wii’s Balance Board (or whatever extrapolation of the technology is devised) be when the subject needs to pee, is tired, is irritated at her husband for forgetting to make car rental reservations, and is angry at little Timmy for swallowing that penny he found on the floor? It’s just one more impediment to the vast majority of us who aren’t doing anything wrong.
As an interesting aside, it does make me think of a story in Wired from March of this year, where defense attorneys wanted to introduce evidence from an MRI to establish a defendant’s innocence. (The request was apparently withdrawn later that month.) In short fMRI works this way:
Laboratory studies using fMRI, which measures blood-oxygen levels in the brain, have suggested that when someone lies, the brain sends more blood to the ventrolateral area of the prefrontal cortex. In a very small number of studies, researchers have identified lying in study subjects with accuracy ranging from 76 percent to over 90 percent. But some scientists and lawyers like Greely doubt that those results will prove replicable outside the lab setting, and others say it just isn’t ready yet.
(Source is the Wired article, with internal linking omitted.)