Sep 24 2008

Homeland Security “Reads Minds”

Well, that’s what the headline says, anyway. Headlines are often misleading. They are often written by headline writers, not the journalists who write the articles, and they are optimized to titillate and intrigue, not to accurately represent the content of the article.

Still, such gross misrepresentation is irritating.

The technology being discussed is an experimental airport scan that would read a a passenger’s body temperature, facial expressions, and other biological markers and infer from them stress level, which will then be used as a warning sign of terrorist intentions.

There is nothing overtly pseudoscientific about such an approach. Humans are emotional creatures, and emotions have a biological component to them. We wear our emotions on our faces, body language, and even autonomic function.

This is the same basic concept as lie detectors – measuring stress as a marker for lying. But, as with lie detectors, the “uncertainty principle” of such technologies is human variability. Someone who is “cool as a cucumber” could theoretically beat such technology. Perhaps a bit of training might be enough. Also, individuals may be nervous for a host of reasons that have nothing to do with planning to blow themselves up. Also, some people are just sweaty and agitated at baseline, even without emotional stress. Maybe they have an overactive thyroid gland.

There are two relevant questions, as far as I can see: how accurate is the technology, and how will it be used.

Accuracy of screening tests, which is what this is, involved both specificity (how often are positive tests true-positives) and sensitivity (how many true-positives will be missed and called negative). You generally want screening testing to be very sensitive, even at the expense of some specificity – as long as you have a follow up test that is more specific.

Homeland security won’t say what the results of their internal tests are (it’s classified), but they did report that it was a “home run.”

Assuming the technology works to some degree – how will it be used? It seems that it would be used as an initial screening. Passengers pass through the arch and are scanned in various ways. Those outside of the parameters and looking “suspicious” can then be pulled aside for more thorough and specific assessment.

What will be the ultimate effect of using this technology on airport screening? That, then, is the final question. Will those able to pass this screening earn lax screening elsewhere? Will sweaty people forever have to endure cavity probes to take a flight anywhere? Or will it add specificity and sensitivity to the overall screening process?

I hope these kinds of assessments are made. One of the risks of shiny new technology is that it can be distracting – it can lure the careless technophile away from the real issues.  Net effects of new technology are not always obvious. They need to be studied directly, not just inferred.

One thing is for sure – this new technology does not “read minds.”

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