Experimental Neurosis was tested by Pavlov and colleague, Shenger-Krestonvika. This experiment provided Pavlov with evidence that showed when animals are paired with an event that is not common to them, they might act in unpredictable and crazy ways. His experiment included a dog. When a circle was present, that circle meant that there was food. But when the ellipse was present, that meant that there was no food available. Throughout the duration of his experiment, the dog eventually learned the theory of when food was or was not present. Since the dog was now used to a circle for food, and an ellipse for no food, pavlov and his team began changing the picture of the ellipse to a more circular image, leaving the dog unsure of when food was present. Since this event was not common to the dog, the dog started to become neurotic and squealing and biting during the experiment.
Symbaluk, D. G., Honey, P. L., & Powell, R. A. (2017). Introduction to learning and behavior. Boston: Wadsworth.