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Preferences Pulled a Robot Beyond Its Original Behavior

PrefPI iterated on relative judgments of self-generated trajectories instead of requiring demonstrations of the target behavior.

Published Updated Story ID: mp-2026-10-01-008
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Summary

PrefPI iterated on relative judgments of self-generated trajectories instead of requiring demonstrations of the target behavior.

PrefPI treats preferred trajectories as a conditional generative distribution and amplifies their density ratio against the broader behavior prior through classifier-free guidance. Repeating that step lets a pretrained generative policy move toward behaviors that were rare or absent initially. On real hardware, the authors report increasing object transport height from 10.7 to 19.8 centimeters using 150 preference-labeled trajectories. That measured shift demonstrates the reported task, not unconstrained out-of-distribution control.

Why it matters

PrefPI iterated on relative judgments of self-generated trajectories instead of requiring demonstrations of the target behavior.

Limits and context

  • That measured shift demonstrates the reported task, not unconstrained out-of-distribution control.

Key claims

  1. PrefPI iterated on relative judgments of self-generated trajectories instead of requiring demonstrations of the target behavior.

    Qualification: That measured shift demonstrates the reported task, not unconstrained out-of-distribution control.

    Evidence: source-2026-10-01-008

Sources

  1. arXiv preprint 2609.40165arXiv · primary research

Corrections

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