Krusty's mother paints his face like a clown for halloween and holds him up to look at himself in the mirror. krusty laughs, and rubs his hands all over his own cheeks making a mess of the paint job! given his behavior, the youngest you should expect jimmy to be is

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.

sounds good to me mate!