The answer is: Increased role taking
In hypnosis, increased role taking refers to a set of behaviors and actions that commonly do not exist if we are not under a hypnotic condition.
If the hypnotic suggest that we are an animals just like what being done to Nikki, we can start to subconsciously adopt the behaviors and actions that we know to be common among those animals. This is why Nikki is hopping around and making monkey-like calls.
