Alec Radford and colleagues at OpenAI announced research showing that a model trained only to predict the next character in Amazon reviews learned an excellent unsupervised representation of sentiment. The model contained a single "sentiment neuron" carrying almost all of the sentiment signal, and achieved a then state-of-the-art 91.8% accuracy on the Stanford Sentiment Treebank. The result bolstered the view that unsupervised next-token prediction could serve as pretraining.