Dog trained to respond to tactile cues from motors inside vest
Auditory cues and visual cues are both useful when training dogs because they each have their advantages. Auditory cues can work even when the dog is out of sight, and visual cues are still functional when an area is too noisy for dogs to hear what someone says. Though dogs tend to learn visual cues faster than auditory ones, both sensory modalities are good ways to give cues to a dog. Tactile cues are another option, and recent work by scientists at Ben Gurion University in Israel have shown that dogs can learn to respond to such cues.
via Whisker Therapy