Have you ever written a word down, looked at it, and thought to yourself, “What a strange word? Is that really a word? Is it actually spelled like that?” Or maybe you said a word a few times – “canoe, canoe, canoe” – and then become confused as to whether that was a real word? No? Uh, me neither. If it did happen to me, I’d be curious as to why. Now I know. The effect is known as semantic satiation and there is a lot of information found in this old, purple and violet paper from the 1960’s. A pubmed search shows that there are still a few researchers working on the effect, but it looks a little dead. I guess it’s not that sexy.
Semantic satiation can be measured in a number of ways. The 1967 paper favors index the transformation of self-reported intensity of meaning of a repeated word. By looking at this index over time, one sees an inverted U-shaped curve. The authors suggest that the rising part of the curve is due to “semantic generation”, indicating an increase in meaning as the word is at first repeated. The falling portion is satiation and inhibition where the ‘meaning’ of the word falls. This satiation appears less frequently or not at all in the extremely young, the elderly, and in older mentally-challenged children.
What causes the satiation? It is unclear. The older paper has a lot of speculation and no real evidence. The newer paper presents data from EEG experiments. They focus on the N400 part of the ERP which is known to be affected by semantic tasks. For instance, the N400 is larger in response to words that are misplaced in their semantic contex. When subjects were asked to simply repeat a word, no change in the N400 was found. In a seperate experiment, the N400 was examined after priming. In this case, after heavy repetition of a primed word there was a decrease in the N400 following presentation of a related cue word versus the low repetition case. This would suggest that satiation – or at least some aspect of repetition – could be affecting the semantic meaning of the word.