This is strongly related to parenting where attention to negative behavior reinforces it - partly no doubt by making it more the topic of thought. So every solution invented by parenting should be applicable to the question of how to 'fetch positive queries',

This is the main topic of the following article: http://www.motherinc.com.au/magazine/kids/kids-education/476-negative-and-positive-commands

There is the following advice:

Parents frequently ask, “Is it ever useful to say what we don’t want?” Sometimes we can get an idea across better if we start by saying what we don’t want. This is particularly true if the child is already doing an undesired behaviour. After saying “Don’t do that,” to get her to stop, it’s very important to immediately tell our child what we do want: “That’s too loud, Amy. I’d like to have you talk a little softer, like this (demonstrating with your voice), OK?”

This contains the initial insight that you have to first notice (in this case helped by the parent) that you are following a negative query. And then go on to follow the positive opposite.

Children don’t learn by being told what not to do, they learn by seeing and hearing what to do.

This of course is the same as looking and doing what other people do in that situation.

If a mother rushes to a child on a ledge and shrieks “Be careful! Be careful!” with terror in her voice, the negative outcome is expressed nonverbally.

This matches the aspect that the words alone aren't the key to whether your brain is put into 'negative fetching' mode. You emotional state is key to that too.

Putting it together this means that you should be able to train positive fetching by using standard positive reinforcement techniques. This should work best with a partner providing the feedback.