Horrifying footage in which a baby is conditioned to fear fluffy animals and Santa Claus has emerged online - in what is considered to be one of early twentieth century psychology's most unethical experiments.

Before there was a code of conduct for psychological research which ensured the subject's consent and mental well-being, John Watson of John Hopkins University Hospital performed the 'Little Albert' experiment in 1919.

The aim of the perverse experiment was to show that an emotionally stable nine-month-old infant - referred to as 'Albert B' - could be trained to have a phobia of something he wasn't scared of before.

In the chilling experiment, the psychologists make loud noises every time the baby touches one of the animals he is interested in. Here, the child shakes hands with a dog, before he is made to fear it

In the chilling video, Watson and his graduate student Rosalie Rayner are seen making loud noises every time the baby sees one of the fluffy animals or Santa Claus.

This traumatises the baby until he is visible terrified every time he sees them.

Today the 'Little Albert' tests are arguably one of psychology's most morally dubious experiments.

However the research was also ground-breaking for the time and is considered the first modern-day experiment of its kind to show that a human could be classically conditioned.

And the mysterious fate of Albert B has also fascinated and bewildered scientists ever since.

The goal of Watson's controversial experiment was to show how principles of 'classical conditioning' - which had been recently discovered by Ivan Pavlov - could be applied to condition fear of into a baby.

For the study, Watson chose a nine-month old boy from the John Hopkins University hospital who they called 'Albert' for the experiment.

The baby is also a rabbit, which he is immediately drawn to in the phase before he is conditioned to fear it

In the footage, Watson begins by presenting Little Albert with objects that he is not afraid of.

These include a rabbit, a dog, a monkey, a Santa Claus mask and a white rat. The little baby is particularly taken with the rat.

But when Watson presents Little Albert with the white rat for the second time, a loud iron rod is struck when the infant attempts to touch the animal.

In the clip, the child initially falls forward startled but does not cry yet.

However when Little Albert tries to touch the rat for the third time, the loud iron rod is struck again and the infant begins to cry.

This act is repeated several times until Watson and Rayner simply presents the white rat by itself and the boy shows fear.

After initially admiring a mask of Santa Claus, when the baby sees it a second time he reels back and cries. This shows how the researchers made him fear fluffy things by making loud noises when he touched them

Later during the video, in an attempt to see if the fear has transferred to other objects, Watson presents Albert with a rabbit, a dog, the Santa Claus mask and a fur coat.

He cries at the sight of all of them - showing how Watson has successfully conditioned the baby to feel fear of these objects.

John Watson of John Hopkins University Hospital performed the 'Little Albert' experiment in 1919

In a particularly disturbing twist to the experiment, Watson and Rayner make no attempt to reverse the psychological trauma they have inflicted on Albert.

It is believed that Watson had discussed what could be done to 'uncondition' the child but made no attempt to actually desensitize him.

What happened to 'Little Albert' is hard to say, in part because no-one is really sure of the child's true identity and is one of psychology's greatest mysteries.

Analyses of Watson's film footage suggest that the infant was mentally and developmentally disabled.

A 2009 report claimed that the child was Douglas Merritte, the son of a wetnurse named Arvilla Merritte who lived and worked at a campus hospital at the time of the experiment - receiving $1 for her baby's participation.

Records show that Douglas died from congenital hydrocephalus at the age of six so it can not be concluded what lasting effect the experiment had on his life.

However the Little Albert experiment would never be allowed under modern-day law and regulations, as it clearly subjected the infant to severe stress and it's likely that the infant's fear of furry things continued post-experimentally.

Before conditioning: The baby, illustrated by John Watson, sees a white rat and takes an instant interest in the rodent

This illustration shows the baby being shown a Santa Claus mask after conditioning and immediately turning away from it

Nonetheless the footage shows what remains to be one of the most influential psychological studies of the early twentieth century - that will never be forgotten for its cruel methods.

The experiment is similar to an opening scene in Aldous Huxley's dysopian novel Brave New World, in which poor children are conditioned to dislike books.

It is unclear whether Huxley was directly influenced by the Little Albert experiment, which happened just over a decade after the book was published.