Responses to visual stimuli is a fancy way of saying how a dog responds to moving objects. For purposes of training, it relates to the dog's "distractibility" when faced with something that moves.

This, too, varies from breed to breed, as well as the nature of the moving object. Terriers are notoriously distractible. Our Yorkshire Terrier, although technically a member of the Toy Group, was convinced that every moving leaf or blade of grass had to be investigated. Although this made perfect sense to him, it made training him to pay attention a real challenge.

In the Hound Group, some breeds, such as Afghan Hounds, Borzois, or Salukis, called sight hounds, are not much interested in objects close by and, instead, focus on those far away.

The guarding breeds, such as the German Shepherd, Doberman Pinscher, and Rottweiler, were bred to survey their surroundings - to keep everything in sight, as it were.