Why does a word look strange if you keep staring at it?

When you see a word, your brain connects its sound and shape to its meaning. Repeat the same word dozens of times in a short period, and that connection activates again and again, gradually responding less strongly.

Then ‘sagwa’ (사과, ‘apple’) starts to sound like just ‘sa’ and ‘gwa’ rather than a fruit. The word itself has not changed; the part that attaches its meaning is taking a brief rest.

The name “semantic satiation” was coined by Leon Jakobovits James, a psychologist at McGill University in Canada, in his 1962 doctoral dissertation. Earlier, in 1960, he and Wallace Lambert of the same university had college students say a single word aloud two or three times per second for 15 seconds, then rate how the word felt. Feelings such as good or bad and strong or weak faded toward the middle of the scale.

Sitting quietly for the same time, or saying a different word, caused almost no such change.

It's easy to think this only happens when you say a word out loud many times, but staring at written words for a long time does something similar. As early as 1907, American psychologists reported that gazing at a word for a long time reduced the associations it brought to mind. In Korea and Japan it is often called “Gestalt collapse,” a term that also covers the feeling that the shapes of letters are falling apart.

It isn't a sign that your memory is failing, either. It's a normal response that happens to everyone, and it fades on its own after a short break.

After revising a report for a long time, a perfectly correct word can suddenly look misspelled. When that happens, it's better to do something else for a moment or check a dictionary before changing it.

Jakobovits James also looked for ways to put the effect to use. In a 1966 paper, he proposed that people who stutter could deliberately repeat the words they fear to soften the tension those words carry, and he suggested it might also be used in treating phobias.