There are studies that say the opposite. The critical differences between this study and those that occurred previously is that this study took place in a far more formal environment, used far more sophisticated equipment, used only very experienced officers, and had a much smaller sample size.
The most obvious reason for the difference in outcome in my mind is that the officers here would be carefully observed by their peers, whereas previous studies were anonymous and private.
The largest scale and most rigorous studies of this sort have shown that officers are either the same or slightly less likely to shoot unarmed black targets than unarmed white targets. Also, compared to the non-cops, officers are also much more accurate in assessing objective threats, rarely shoot unarmed victims, are less "trigger happy", despite being much faster in making these more accurate decisions to shoot. Absurdly, the one result that gets focused upon is that they were 10 hundreds of a second slower to decide whether to shoot with black targets even though they still decided in about 1/2 second, which is an utterly meaningless result in relation to real world situations.
