🤔Large Language Models Pass the Turing Test.

Turing Test: A recent paper by a UCSD team on arXiv mentions that LLMs have now been able to pass a true Turing Test. The experiment recreated the original three-party Turing Test, in which an interrogator engages in text-based conversations—without knowing their identities—with both a randomly selected human and an AI (e.g., GPT-4.5, LLaMa, etc.). These two participants are referred to as witnesses. After 5 minutes, the interrogator must decide which participant is the human, providing both a written justification and a confidence score.
During the test, the two witnesses communicate with the interrogator via separate windows on the left and right, but they cannot see each other’s conversations. This is also known as a triple-blind experiment. The specific chat interface is as follows:
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Experiment Setup: The experiment recruited a total of 126 undergraduate psychology students from UCSD and 158 participants from the Prolific platform. Each human participant took part in 8 rounds of testing, randomly serving as either the interrogator or the witness in each round. This means that on average, each person interacted with an AI in about 4 rounds.
Additionally, the researchers designed two types of prompts for the AI models:
  1. Basic Prompt (NO-PERSONA): The model was simply instructed to try to convince the human that it was a real person.
  1. Persona Prompt (PERSONA): The model was given a specific personality to portray—that of an introverted young person who is familiar with internet culture and frequently uses slang in casual conversation.
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Key Findings:
  • When GPT-4.5 was prompted with the persona mode, it was judged to be human 73% of the time—significantly higher than the actual human participants.
  • LLaMa-3.1-405B, using the same persona prompt, had a "win rate" of 56%, which was not statistically different from humans. (this is creepy enough though)
  • In contrast, more basic models like ELIZA and GPT-4o performed well below random guess level, with only 23% and 21% of judges identifying them as human.
ELIZA is an early chatbot program developed by Joseph Weizenbaum in 1966, and is considered a classic in the history of AI. Unlike modern LLMs, ELIZA relied on pattern matching and template substitution to generate replies. For example, it would extract keywords from a user's input and match them with predefined response templates. In this study, ELIZA and GPT-4o were used as baseline comparisons.
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From the above results, it’s clear that persona prompts have a statistically significant impact: both GPT-4.5 and LLaMA performed noticeably better than real humans when operating under the persona condition (ironically, the imitated human seemed more real than the real one...). However, the same models without a persona performed much worse, which really underscores the importance of prompt engineering.
Of course, passing a Turing Test doesn’t necessarily mean the model has human-level intelligence or consciousness. It just shows that today’s LLMs have become extremely good at mimicking humans—or maybe more precisely, that they’ve been well-trained in role-playing 🎭😂.
Participant Biases:
  • Among the general population recruited from Prolific, several factors were significantly correlated with accuracy in identifying the AI:
    • Gender differences played a notable role: accuracy varied significantly between genders.
    • The more rounds a participant played, the worse they got at correctly identifying the AI.
    • The more confident participants felt, the less accurate they were in reality (which is... kinda hilarious).
  • However, none of these trends held in the undergraduate student group.
    • The only significant correlation found among UCSD students was:
      The more confident they were, the more accurate they actually turned out to be — at least showing a positive trend overall.
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Interrogators’ Strategies for Spotting the AI:
  • In most conversations, interrogators tried to determine if they were talking to an AI by asking about daily life, personal opinions, or specific life details. Some even just bluntly asked, “Are you a human or a bot?”
  • But here's the twist: the people who were actually good at identifying AIs didn’t rely on those everyday questions. Instead, they used:
    • Weird or unusual talking approach (out-of-distribution data actually), designed to trip the model up
    • LLM jailbreak-style tricks, trying to “trap” the AI into revealing itself
  • Interestingly, the strategy of asking normal, casual stuff ended up performing even worse than random guessing — a strong hint that LLMs have gotten very good at sounding human nowadays, although still struggle with the unexpected from professionals.
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