Little Albert experiment
Watson & Rayner's (1920) experiment on 'Little Albert' demonstrated that classical conditioning principles could be applied to condition the emotional response of fear.
according to today's ethical standards, the nature of the study itself would be considered unethical, as it did not protect Albert from psychological harm, because its purpose was to induce a state of fear. Many sources claim that Little Albert was used as a subject in the study without the permission of his mother. Albert was also withdrawn from the hospital by his mother, which meant that there was no removal of negative effects caused by the study and Albert's psychological wellbeing following his experience has never been ascertained.