The digital history of the anglophone vocabulary of psychology: An exploration using Zipfian methods

The digital humanities are being applied with increasing frequency to the analysis of historically important texts. In this study, the methods of G. K. Zipf are used to explore the digital history of the vocabulary of psychology. Zipf studied a great many phenomena, from word frequencies to city sizes, showing that they tend to have a characteristic distribution in which there are a few cases that occur very frequently and many more cases that occur very infrequently. We find that the number of new words and word senses that writers contribute to the vocabulary of psychology have such a Zipfian distribution. Moreover, those who make the most contributions, such as William James, tend also to invent new metaphorical senses of words rather than new words. By contrast, those who make the fewest contributions tend to invent entirely new words. The use of metaphor makes a text easier for a reader to understand. While the use of new words requires more effort on the part of the reader, it may lead to more precise understanding than does metaphor. On average, new words and word senses become a part of psychology's vocabulary in the time leading up to World War I, suggesting that psychology was "finding its language" (Danziger, 1997) during this period.