Have you ever tried the experiment of saying some plain word, such as 'dog,' thirty times? By the thirtieth time it has become a word like 'snark' or 'pobble.' It does not become tame, it becomes wild, by repetition. ~G.K. Chesterton

Semantic satiation, also known as semantic saturation, is a psychological phenomenon, where the repetition of a word or phrase causes it to temporarily lose meaning for the listener, who then perceives the speech as repeated meaningless sounds. Inspection of a word or phrase for an extended period of time produces the same effect.

Although semantic satiation is fairly common, it has been found out that words we have strong associations with tend to take more time to lose meaning than words that are less familiar to us.

In 1907, E.Severance and M.Washburn first described the concept of semantic satiation in The American Journal of Psychology:

If a printed word is looked at steadily for some little time, it will be found to take on a curiously strange and foreign aspect. This loss of familiarity in its appearance sometimes makes it look like a word in another language, sometimes proceeds further until the word is a mere collection of letters, and occasionally reaches the extreme where the letters themselves look like meaningless marks on the paper.

The term was first used by psychologists Leon James and Wallace E. Lambert in the article ‘Semantic Satiation Among Bilinguals’ published in the Journal of Experimental Psychology in 1961.

James conducted several experiments demonstrating the effect of semantic satiation in cognitive tasks. The subjects would repeat a word or number for several seconds and then perform a cognitive task using that word. It was found that repeating a word before using it in a task made the task more difficult.

The explanation given for the phenomenon is that when a word or phrase is repeated, it arouses a specific neural pattern in the cortex that corresponds to the meaning of that word or phrase. The neural cells of the central and peripheral region of the brain fire repeatedly due to continuous repetition. This results in reactive inhibition. Thus there is a reduction in the intensity of the activity with each repetition. In James' words:

It’s a kind of a fatigue...It’s called reactive inhibition: When a brain cell fires, it takes more energy to fire the second time, and still more the third time, and finally the fourth time it won’t even respond unless you wait a few seconds. So that kind of reactive inhibition that was known as an effect on brain cells is what attracted me to an idea that if you repeat a word, the meaning in the word keeps being repeated, and then it becomes refractory, or more resistant to being elicited again and again.

A noteworthy application of this phenomenon is reduction of speech anxiety. Semantic satiation is created in the stutterer through repetition, thereby lessening the degree of intense negative emotions triggered during speech. Semantic satiation has also been used as a tool to gain insight into studies on multilingualism.

I began to indulge in the wildest fancies as I lay there in the dark, such as that there was no such town, and even that there was no such state as New Jersey. I fell to repeating the word 'Jersey' over and over again, until it became idiotic and meaningless. If you have ever lain awake at night and repeated one word over and over, thousands and millions and hundreds of thousands of millions of times, you know the disturbing mental state you can get into. ~James Thurber, My Life and Hard Times