Expression of emotion in books declined during 20th century, study finds

The use of words with emotional content in books has steadily decreased throughout the last century, according to new research from the Universities of Sheffield, Bristol and Durham. The study, published today in PLOS ONE , also found a divergence between American and British English, with the former being more 'emotional' than the latter. The researchers looked at how frequently 'mood' words were used through time in a database of more than five million digitised books provided by Google. The list of words was divided into six categories (anger, disgust, fear, joy, sadness, surprise) previously used by a co-author Dr Vasileios Lampos, from the University of Sheffield's Department of Computer Science and the Natural Language Processing Group, to detect contemporary mood changes in public opinion as expressed in tweets collected in the UK over more than two years. Dr Lampos said: "The initial idea was simple: what if we apply a similar analysis on digitised books? And even the very first experimental results were depicting clear patterns of correlation between historical events and mood tendencies, such as the obvious peak in sadness during the Second World War." Dr Alberto Acerbi, a Newton Fellow in the Department of Archaeology and Anthropology at the University of Bristol and lead author of the paper, said: "We thought that it would be interesting to apply the same methodology to different media and, especially, on a larger time scale. We were initially surprised to see how well periods of positive and negative moods correlated with historical events.