Over the years, in an effort to understand more about the human psyche many scientists, psychologists, and doctors undertook experiments that were anything but humane. 

Here are some of the most shocking experiments conducted on humans over the history: 

1.  Stanford Prison Experiment (SPE) in 1971

Specifically focusing on the struggles between prison inmates and prison guards, SPE was a social psychology experiment that attempted to understand the psychological effects of perceived power. Psychology professor Philip Zimbardo randomly assigned volunteers (who were college students) as 'guards' or 'prisoner' in a mock prison (set up at the Stanford University). The experiment, that was abandoned in just six days, saw students immediately take to their assigned roles - and go so far as to psychologically and physically harass prisoners. Years later, a movie was also based on the experiment, titled The Stanford Prison Experiment

Source: prisonexp.org

2. The Neubauer twin experiment in 1961

As part of an undisclosed scientific study, three identical triplets were intentionally separated at birth and placed with families with different parenting styles and economic levels under the direction of psychiatrists Peter B. Neubauer and Viola W. Bernard. The triplets accidentally discovered each other when they were 19 through a college connection, and that led to the discovery of a cruel psychological experiment - the details of which are still a mystery. All three faced mental health issues while growing and one of the triplets even committed suicide. The documentary, Three Identical Strangers, deals with their discovery and lives. 

Source: YouTube

3. Milgram Experiments in 1963

Stanley Milgram, a Yale University psychologist, conducted perhaps one of the most famous and shocking 'obedience studies' in psychology. The justifications for genocide provided during the Nuremberg War Criminal trials included obedience, i.e. following superiors' orders. To test the same, Milgram selected 20 random volunteers, paired them with confederates (people pretending to be participants), and divided them as 'teachers' (always volunteers) and learners (always confederates). The teachers had to administer an electric shock to the learner if the learner committed a mistake, and when the teacher hesitated (the shocks were as high as 450 V), the examiner prompted the teacher to continue - which 63% of the participants did. 

4. Operation Midnight Climax in the 1950s

A sub-project of CIA's mind-control research program Project MKULTRA, Operation Midnight Climax was established by American chemist and spymaster Sidney Gottlieb. In an attempt to study the effects of LSD, unconsenting adults were slipped the drug and kept in safe houses where they were monitored. Initially, prostitutes on the CIA payroll lured clients into safe houses. Later, operatives dosed people in beaches and restaurants. 

Source: Ripleys

5. Bobo Doll Experiment in 1961

Bandura, Ross, and Ross conducted the Bobo Doll experiment to test if social behaviors like aggression could be acquired by observation and imitation. For the purpose of the experiment, they tested 36 boys and 36 girls aged between three to six years old. The children were shown aggressive behavior, where a Bobo Doll was attacked by an adult model. The children were quick to imitate the actions when they played with the doll. However, the experiment was criticized for exposing children to violence for drawing a result that was considered as natural. 

Source: ambikasole

6. Little Albert Experiment in 1920

Conducted by John B. Watson and his graduate student, Rosalie Rayner at the John Hopkins University, the Little Albert experiment aimed to study evidence of classical conditioning in humans. Simply put, for the purpose of their study, they forcibly introduced in a phobia in a nine-month-old child, who was emotionally stable at the start of the experiment. Though no objections were raised at the time, the experiment is clearly unethical. Whether the child continued to battle the phobia (of white, furry objects) was never determined. 

7. Monstery Study in 1939

Proposed by psychologist Wendell Johnson, Monster Study was a stuttering experiment conducted on 22 orphan children. The children were divided into two groups - one received positive speech therapy and the other received negative speech therapy i.e. being belittled for their speech imperfections. The second group developed speech problems, even if there weren't any when the experiment started. In fact, many children continued to have speech problems their whole lives. The study was conducted in Iowa, and the University of Iowa publicly apologized for the study in 2001. 

Source: learning-history

Irrespective of the motive, these experiments prove that even in the past human life was not given the importance and value it deserves.