Methods and evaluation

How multimodal AI detection is evaluated

This page explains useful signal families, evaluation metrics, and public reference datasets. It does not publish a universal accuracy claim because performance changes by model, sample, language, transformation, and threshold.

  • Text
  • Image
  • Code
  • Voice and audio
  • Video

Signal families by modality

These are common signal categories for interpreting detector output and designing representative evaluations. No individual signal proves authorship.

Generated text

Signals to examine

Text evaluation can combine statistical writing signals, classifier output, and robustness checks across editing and paraphrasing.

Evaluation checks

  • Sentence variation
  • Stylometric patterns
  • Model-family shift tests
  • Paraphrase robustness
Report
AUROC, FPR, FNR, calibration
Useful evidence
Sentence-level indicators and confidence context.
Reference samples
Public corpora and held-out samples

Generated code

Signals to examine

Code evaluation should separate common boilerplate from generator-associated patterns and test how results change after human edits.

Evaluation checks

  • Structure and identifier patterns
  • Comment and documentation signals
  • Language-specific baselines
  • Human-edit robustness
Report
AUROC, FPR, FNR, calibration
Useful evidence
Function-level indicators with repository context.
Reference samples
Versioned human and AI code samples

Voice cloning and synthetic speech

Signals to examine

Audio evaluation can examine spectral, timing, prosody, and channel signals across clean, compressed, and re-recorded samples.

Evaluation checks

  • Codec robustness
  • Noise and replay tests
  • Speaker consistency
  • Clip-length analysis
Report
EER, FPR, FNR, calibration
Useful evidence
Timestamped spectral and prosody indicators.
Reference samples
Public anti-spoof datasets and held-out audio

Generated music

Signals to examine

Music evaluation can compare spectral repetition, timbre, structure, and metadata while accounting for mastering and distribution changes.

Evaluation checks

  • Spectral consistency
  • Structure and repetition
  • Codec robustness
  • Source metadata review
Report
AUROC, FPR, FNR, calibration
Useful evidence
Segment-level indicators with source context.
Reference samples
Versioned human and generated music samples

Deepfake and generated video

Signals to examine

Video evaluation should test frame-level, temporal, face, and audio-video consistency across resolution and recompression changes.

Evaluation checks

  • Temporal consistency
  • Face-region review
  • Audio-video alignment
  • Recompression robustness
Report
Clip AUC, frame AUC, FPR, FNR
Useful evidence
Frame and timestamp-level indicators.
Reference samples
Public deepfake datasets and held-out video

Public datasets relevant to evaluation

DatasetDomainNotesMetric(s)
HC3 / HC3+TextHigh-quality ChatGPT vs HumanAUROC, FPR@TPR
RAIDTextAdversarial attacks & domainsRobustness Score
AIGCodeSetCodePython generation tasksAUROC
ASVspoof 2019/21AudioLogical/Physical AccessEER, min t-DCF
ADD 2022AudioAudio Deepfake DetectionEER
DFDCVideo100k+ clips, Facebook backedVideo-AUC
FaceForensics++VideoDiverse manipulation methodsFrame-AUC
Celeb-DFVideoHigh-quality DeepfakesAUC

These datasets are public references for designing evaluations. Listing a dataset does not claim a published ZeroTrue score on it.

Evaluation Metrics

Text

AUROC

Across thresholds

Measures class separation across thresholds. Report false positives and calibration alongside it.

Code

AUROC

By language

Results should be separated by programming language, source, and degree of human editing.

Audio

EER

Error tradeoff

Equal Error Rate summarizes the tradeoff between false acceptance and false rejection.

Video

Clip AUC

Frame and clip

Report clip-level and frame-level behavior separately, including recompressed samples.

Operational Bands

Illustrative labels for reading confidence with policy context.

  • Lower confidence
  • Manual review
  • Higher confidence

Evaluation priorities

  1. Coverage

    Generator and domain shift

    Test held-out generator families, languages, media sources, and content domains.

  2. Robustness

    Transformation resistance

    Measure behavior after compression, cropping, paraphrasing, editing, replay, and re-recording.

  3. Quality

    Calibration and error analysis

    Publish false positives, false negatives, confidence calibration, model version, and test date.