Difficult to judge: Better sight doesn't mean "better human-like sight". Maybe dogs are better at seeing fast moving gradients (e.g. when racing prey), but have

Difficult to judge: Better sight doesn't mean "better human-like sight". Maybe dogs are better at seeing fast moving gradients (e.g. when racing prey), but have difficulties with slow changes (e.g. predator slowly closing in). Also, maybe the dogs just assumed that /you/ would be looking out for any "enemies", and were then just surprised because you didn't warn them about the impeding "attack" while they had other things in mind ;-)