Mackaques love touchscreens, amd can be trained to do complex tasks on tablets placed in their enclosures.
You make a test where they need to press a button when and only when they see tiny monkeys that you can project on a screen or on their floor.
Then you give the drug at various concentrations and placebo, and see if there is a dose dependent increase in the monkeys indicaions of mini monkeys.
Then you can repeat the experiment after treatment with antipsychotic, if it prevents the mini monkey reporting, you already have a hint at the mechanism.
Any nonhuman primate lab can do this from 1-2 million dollars, should we start a go fund me?