  Human communication is increasingly intermixed with language generated by AI.
Across chat, email, and social media, AI systems suggest words, complete
sentences, or produce entire conversations. AI-generated language is often not
identified as such but presented as language written by humans, raising
concerns about novel forms of deception and manipulation. Here, we study how
humans discern whether verbal self-presentations, one of the most personal and
consequential forms of language, were generated by AI. In six experiments,
participants (N = 4,600) were unable to detect self-presentations generated by
state-of-the-art AI language models in professional, hospitality, and dating
contexts. A computational analysis of language features shows that human
judgments of AI-generated language are hindered by intuitive but flawed
heuristics such as associating first-person pronouns, use of contractions, or
family topics with human-written language. We experimentally demonstrate that
these heuristics make human judgment of AI-generated language predictable and
manipulable, allowing AI systems to produce text perceived as "more human than
human." We discuss solutions, such as AI accents, to reduce the deceptive
potential of language generated by AI, limiting the subversion of human
intuition.
