Researchers have been hunting for proof of widespread bias among Denver police for most of this decade, with inconclusive results. Now they plan to do brain scans of cops - and even test blood and saliva.

Brain scans? Yes, but back to that in a moment. First, it's worth recalling that the formal search for evidence of systematic bigotry began in 2000, with the Biased Policing Task Force. Starting in 2001, officers were required to fill out a "contact card" providing data on every traffic and pedestrian encounter so experts could check for patterns of racial profiling.

Naturally, disparities were found when hundreds of thousands of cards were examined. It would be something of a statistical miracle if that weren't the case. But as a report by two professors at the University of Colorado at Denver acknowledged, "little agreement exists nationally on interpreting these data."

Whites, for example, were more likely than others to be ticketed after traffic stops, while blacks and Hispanics were more likely to be searched. Unfortunately, such differences prove nothing on their own. If they did, then the huge disparity in searches and arrests between men and women would be evidence of police bias, too, when of course it is no such thing.

Comes now the department with another major anti-bias initiative, this one led by Phillip Goss, a social psychologist at UCLA. As described in Tuesday's Rocky, the project sounds mostly like a sensible review of practices with an eye to improving their quality; the retention of female officers has been an issue, for example, which Goff's recommendations have addressed.

But then there is this, according to The Denver Post: "Goff also plans to conduct brain scans of some Denver officers and to sample physiological tissue, such as blood or saliva, to see how they respond to imagery that may detect hidden racial bias."

If you can't find bias in what the cops do, in other words, maybe you can find it in what they think.

First problem: What people think is no one else's business. It's behavior that matters.

Second problem: What if such tests don't actually provide meaningful evidence for bias?

Such scans are among a number of tests used to try to measure unconscious racism. The most popular is the Implicit Association Test, a computer-based exam that you can take online at implicit.harvard.edu/ implicit. (If you're white, chances are high that it will conclude that you "have an automatic preference for whites over blacks.")

Trouble is, as New York Times science writer John Tierney recently pointed out, experts don't agree on what the findings mean.

"In a series of scathing critiques," Tierney writes, "some psychologists have argued that this computerized tool . . . has methodological problems and uses arbitrary classifications of bias. . . . If Barack Obama's victory seemed surprising, these critics say, it's partly because social scientists helped create the false impression that three-quarters of whites are unconsciously biased against blacks."

More important, some researchers believe, the test may be a faulty predictor of actual behavior. "Even though most of the doctors [in one study] registered some anti-black bias, as defined by the researchers," Tierney reported, "on the whole doctors ended up prescribing the clot-busting drugs to blacks just as often as to whites. The doctors scoring low on bias had a pronounced preference for giving the drugs to blacks, while high-scoring doctors had a relatively small preference for giving the drugs to whites - meaning that the more 'biased' doctors actually treated blacks and whites more equally."

Why should we expect brain scans to be any more useful?

Any workplace tests claiming to measure "unconscious racism" are troubling - even if they're voluntary, as in Denver's case - both because of their Orwellian potential and because they undermine reliance on accountability.

We are responsible, after all, for what we can control - our behavior - not for unconscious reactions that remain within our heads.

Vincent Carroll is editor of the editorial pages. Reach him at carrollv@RockyMountainNews.com.