Google presented Meena, a 2.6-billion-parameter conversational model trained end to end for open-domain dialogue rather than any particular topic, reporting that it held conversations more sensible and specific than the chatbots that were then state of the art. To measure it, the team introduced a new metric, Sensibleness and Specificity Average (SSA), capturing basic but important properties of human conversation. The work fed into LaMDA the following year. It shows Google had conversational AI as a research result almost three years before ChatGPT — and did not ship it as a product.