Buckets don't hold much meaning to the dogs and wolves.
In the bucket experiment, the dogs were equally likely to seek food from the person with a bucket over his head as the person holding the bucket. Most dogs haven't learned to read the cue because they don't typically see a person with a bucket over his head.
Monique Udell said:
“For us as humans, having a bucket over your head is very silly,’’ she said. “Dogs and wolves don’t get that. For the most part dogs and wolves would be equally likely to beg from someone with a bucket on your head because buckets don’t hold much meaning.’’