AUDIE CORNISH, HOST:
Protest's over the shooting death of 18-year-old Michael Brown in Ferguson, Missouri spotlighted how police use force.
STEVE INSKEEP, HOST:
That shooting prompted people to ask what role race may have played. In this next story researchers examine other factors that could affect an officer in a confrontation.
CORNISH: Factors like sleep deprivation or even the light in the room. NPR's Martin Kaste has more.
MARTIN KASTE, BYLINE: You go to someone's house on a domestic disturbance call. Inside you see a man has a woman by the neck and he's furious.
UNIDENTIFIED MAN: Police, police. Settle down. Step away from...
KASTE: At the tight hallway and you can't see what the guys got in his right hand. Suddenly that hand swings towards the woman. Think fast.
KASTE: This is, of course, a simulation. The scenario's being projected on a big screen and the man demonstrating it for us is Bryan Vila. He's an academic - but he's also a retired cop. Looking at the gun in his hands, he says that experience just now felt a little too real.
BRYAN VILA: My heart's pounding, my pulses up - 135 or 40 from my normal standing around is about 70. And I know this is a bloody simulation.
KASTE: This is what Vila studies. He runs a Simulated Hazardous Operational Tasks Lab at Washington State University. Normally police use this kind of simulator for training - but by Vila uses it to study the police, when they're under pressure.
VILA: We're hooking people up, we've got heart rate monitors on them, we have brain imaging devices. We measure the deoxygenated versus oxygenated blood - proportions in each at 16 different loci along the frontal lobe.
KASTE: What does all that tell you? Lois James is an assistant researcher on this project. She says is all about measuring a cop's mental stamina.
LOIS JAMES: How much do they still have in the tank?
KASTE: As an officer moves through chaotic high-pressure situations, is there a limit to his decision-making powers? What's the effect of variables like lighting, sleep deprivation or the officers own level of experience? The goal here is to boil down a situation's difficulty to turn that into numbers.
JAMES: We can give a scenario - and overall score and we usually convert that to a percentage just so it's easily interpreted. I believe this is up there at about the 90 percent difficulty.
KASTE: She's talking about that domestic disturbance scenario. And 90 percent is really hard. They call their system, deadly force judgment and decision-making metrics. They developed it for the research branch of the Department of Justice.
JAMES: The methods that we developed they can be used with - after incident reports, for example.
KASTE: Someday soon most controversial uses of force will come with a timeline provided by devices - like body cameras - mix in the other variables from the scene and you could have a score for something that's always been subjective - the difficult of a life-and-death situation. And Brian Vila says that is valuable information for the people who pass judgment on police.
VILA: There aren't a lot of prosecutors, defense attorneys, judges or jurors who've ever been in a deadly encounter. There are probably fewer and fewer every year who have been in a fist fight.
KASTE: Vila's still crunching the data from the 78 officers that he studied in the simulator. He doesn't have broad results yet, but some human limitations are pretty clear.
VILA: In terms of human response times - you can't function faster than about a quarter of a second.
KASTE: And he's also seeing a boundary between conscious judgment and something fuzzier.
VILA: We see - with the brain imaging devices - a lot of effort up to the moment when the decision's made. And then it all goes away because you're out of decision-making mode. And you're into fight mode.
KASTE: It's not that the fog of war should always be used to excuse police actions. But Vila says when we hold cops accountable we need to be fair.
VILA: From an ethical standpoint if you're holding someone accountable for something they have to be able to do it.
KASTE: And if it turns out were asking police to do the impossible, he says it may be time to rethink police tactics - find ways to move back the clock. Maybe train cops to back off more and wait for reinforcements. Whatever the policies are, he says, the goal should be to shift the probabilities in favor of the officers. So that they're less likely to find themselves having to act before they've had a chance to think. Martin Kaste, NPR news.
CORNISH: Tonight on All Things Considered Martin reports on efforts to do just that. To train police to move back the clock, by de-escalating conflicts before deadly force is needed.
INSKEEP: It's Morning Edition from NPR News. I'm Steven Inskeep.
CORNISH: And I'm Audie Cornish.
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