Highlighting a seemingly blank space in a preprint on arXiv reveals an AI prompt. (Photo by Kaori Yuzawa)TOKYO -- Research papers from 14 academic institutions in eight countries -- including Japan, South Korea and China -- contained hidden prompts directing artificial intelligence tools to give them good reviews, Nikkei has found.Nikkei looked at English-language preprints -- manuscripts that have yet to undergo formal peer review -- on the academic research platform arXiv.It discovered such pr...