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Comparing Traditional and LLM-based Search for Consumer Choice: A Randomized Experiment

How LLM-based search affects efficiency, accuracy and user perception compared with traditional search, and the role of confidence cues.

Research Questions

  1. How does LLM-based search affect efficiency, accuracy, user perception, and error handling compared to traditional search methods?
  2. How can users’ overconfidence in incorrect LLM outputs be reduced?
  3. How do confidence signals (e.g. colour-coded confidence indicators) influence user behaviour?

Results

  • LLM-based search cut task completion time in half (1.6 min vs. 3.4 min).
  • Users submitted fewer but more complex queries.
  • Accuracy was similar for routine tasks, but on the task that contained an error, LLM users’ accuracy dropped sharply (47% vs. 93%).
  • Participants found the LLM experience more satisfying.
  • Confidence cues (colour coding) helped users detect errors and doubled accuracy.

Findings

  • Efficiency:
    • LLM search was 50% faster, and queries were fewer in number but more complex.
  • Accuracy & Overconfidence:
    • Users performed well on standard tasks, but when the dataset contained an error, LLM users showed strong overconfidence in incorrect answers.
  • User Perception:
    • Although the LLM experience felt more satisfying, users often failed to notice mistakes.
  • Mitigation (Experiment 2):
    • Confidence cues (green = high confidence, red = low confidence) increased accuracy from 26% to 53–58%. Users also ran more follow-up queries to test uncertain outputs.

Scores

  • LLM Models: 4
  • Synthetic Data: 0
  • Method: 5
  • Speed: 5
  • Ethics: 3
  • Accuracy: 5
  • Demographics: 0

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