The dog's attention is fixed to a particular object, like a towel or a piece of plastic tubing that has knapweed wrapped inside.

[6] Since Nightmare was expected to work on her own out in a large pasture locating small rosettes of knapweed as it invaded an area, she needed to be able to cover the field without chasing after wildlife or stray scents.

As her proficiency increased, the trainers added various distractions, to help Nightmare learn to stay focused solely on her task.

Nightmare has a 93 percent success rate overall in locating the invading non-native spotted knapweed.

[8][9] She followed it up with 98% in the final trials in open fields, demonstrating that dogs can effectively detect low densities of invasive plants.