The Department of Justice’s report on the Ferguson Police Department is full of eye-catching numbers that reveal a culture plagued by significant racism. Statistically significant. For instance, nearly ninety per cent of the people who prompted a “use of force” by the F.P.D. were black. Even among such skewed percentages, there are some standouts. Among cases in which a suspect was bitten by an attack dog and the suspect’s race was recorded, what percentage were black?

A hundred per cent.

There is little nuance in the incidents described in the report; the police simply sicced their dogs on unarmed black males. According to the F.P.D’s own guidelines, handlers should not release the hounds “if a lower level of force could reasonably be expected to control the suspect or allow for the apprehension.” But the report reveals that the F.P.D. is quick to set loose its trained attack dogs—often on black children.

The damning DOJ report on Ferguson is a great example of data as an objective racism detector. This might be an example of dogs revealing the racism of their owners.

A 2011 study published in the journal Animal Cognition found that even expertly trained dogs and the most professional handlers cannot evade what is called the Clever Hans effect. In tests, dogs trained to detect explosives and drugs were sent, with their handlers, into a series of rooms to find non-existent contraband. In one room, there was a decoy that had been scented with sausage; in another, there was an unscented decoy accompanied by a sign telling the handler, falsely, that it smelled of contraband; a control room had no decoys. The investigators found, overall, that “human more than dog influences affected alert locations”: the meat decoy attracted more false alarms than anything in the control room, but the decoy with the sign prompted nearly twice as many false alerts as the one with the tempting scent. In other words, the dogs found their handlers’ unconscious cues significantly more compelling than the sausage. Trained animals, it turns out, are arguably better at reading our cues than we are at suppressing them.

Remember, there are no racist dogs, only racist owners.