“The correlation with mood terms is not altogether surprising, as these longer constructions provide increased opportunity for expressing sentiments,” explains biologist David Krakauer of the University of Wisconsin–Madison, who with his colleagues has mined Google Books for changes in literary style.
“Authors tend to read their contemporaries and their competitors largely within their respective cultures,” he adds, “and so we might expect British English and American English to diverge somewhat.”
Do these shifts imply that the US population in general expresses more emotion than the British? Although that doesn’t necessarily follow — literary norms may sometimes invert rather than mirror tendencies in everyday life — Acerbi feels that the findings “may reflect a genuine cultural change, because of the size of the sample, and because Google Books is not explicitly biased towards successful or influent books”.
But Krakauer cautions that differences in literary expression don’t necessarily represent differences in the emotional mindscapes behind them. “It is a rather intriguing and open question why different cultures express the same level of feeling with different numbers of words,” he says.