A psychologist explained to jurors how police officers like Kim Potter can mistake their guns for Tasers

• Dr. Matthew Miller took the stand in ex-cop Kim Potter's manslaughter trial on Friday.
• Potter has said she confused her gun for her Taser when she fatally shot Daunte Wright in April.

Former Minnesota cop Kim Potter's defense called a psychologist to the witness stand Friday to explain to jurors how police officers may confuse their gun for a Taser.

Potter is being tried on first- and second-degree manslaughter charges in the shooting death of Daunte Wright during a traffic stop in April. She has said that she intended to grab her Taser, which was holstered on the opposite side of her body, when she shot Wright in the chest.

The jury has seen body camera footage that shows Potter shout, "Taser! Taser! Taser!" before shooting Wright in the chest while he tries to sit down in the driver's seat of his vehicle. On Friday, Dr. Matthew Miller, a clinical neuropsychologist and professor at Florida Atlantic University, explained to jurors how officers can confuse their weapons through what he called "action errors" and "slip and capture" errors.

Miller explained to the jury that an "action error" happens when an intended action has an unintended effect, such as incorrectly writing the date when signing a check after the turn of a new year. Action errors have nothing to do with "outside interference, willful neglect, or conscious manipulation," Miller said.

"Slip and capture" errors are a subsection of action errors coined by a police psychologist, Miller said, and these errors occur in police work when officers are involved in fast-moving situations with a heightened sense of stress. The most common example of a slip and capture error in police work is weapon confusion, according to Miller, who said confusing a Taser for a gun is "the most typical example of what's meant by weapon confusion."

On cross-examination, prosecutor Erin Eldridge asked Miller whether it's important for officers to know "how to manage their stress," to which Miller responded, "that would be right."

Eldridge brought up an article that Miller wrote in which he used the term "OBM." Miller said that's a term police use in their work to stand in for "one big fuck up." Miller wrote in the article that OBMs often occur "in response to the deer-in-headlights freeze," Eldridge noted, and that "many of these mental chokepoints are preventable through the use of proper training and practice."

Stephen Ijames, a police use-of-force expert, previously testified in the trial that Potter's decision to attempt to tase Wright was "consistent" with police Taser training. However, a different use-of-force expert had testified that Potter's use of deadly force was "excessive and inappopriate."