Experimental neurosis is an abnormal behavioral condition produced in an artificial laboratory setting. The subject is typically placed in a problem solving or discernment scenario they cannot solve because it is too difficult or impossible. This can result in erratic altered behavior that mimics a mental disorder. Experimental neurosis is essentially a psychosis that is produced artificially. The stress of not being able to solve the experimental problem causes the behavior to appear.
Examples of this can be seen in animal experiments. When the animal is first learning what the desired behavior is through reinforcement and punishment it can become confused and stressed. This stress can cause abnormal behavior like aggression or fear of the experimenter which would not be present during normal circumstances. Pavlov noticed in his experiments with dogs that when the dogs were very confused and unable to distinguish between stimuli they would growl and act aggressive towards the experimenters which was abnormal behavior for the well trained dogs.