用随机卷积网络检测政治深度伪造,还能判断结果靠不靠谱。
Conditional Uncertainty-Aware Political Deepfake Detection with Stochastic Convolutional Neural Networks
- 引入随机卷积网络,让模型输出不仅有判断,还有可信度。
- 在真实数据集上,不确定性估计能显著提升高风险场景的决策可靠性。
- 适合需要安全审核的政治内容平台或监管机构使用。
生成图像模型的进步使得高度逼真的政治深度伪造视频泛滥,威胁信息真实性、公众信任与民主进程。尽管自动化检测系统被广泛用于内容审核,但多数仅提供确定性预测,无法说明何时结果不可靠,这在政治高风险场景中是严重缺陷。本文提出基于随机卷积神经网络的条件化、不确定性感知检测框架,从可观察指标(如校准度、正确评分规则)评估不确定性,而非仅依赖贝叶斯理论。通过从大规模真实-合成数据集中筛选构建政治图像二分类数据集,对ResNet-18和EfficientNet-B4两个预训练骨干网络进行全微调。对比确定性推理、单次随机预测、蒙特卡洛丢弃、温度缩放及集成式不确定性代理。评估涵盖ROC-AUC、阈值混淆矩阵、校准指标及生成器无关的分布外性能。结果表明,经过校准的概率输出与不确定性估计可支持风险敏感的内容管理策略。系统性置信区间分析揭示了不确定性在实际操作中的增益边界,明确了其在政治语境下的优势与局限。
原文摘要 · Abstract (English)
Recent advances in generative image models have enabled the creation of highly realistic political deepfakes, posing risks to information integrity, public trust, and democratic processes. While automated deepfake detectors are increasingly deployed in moderation and investigative pipelines, most existing systems provide only point predictions and fail to indicate when outputs are unreliable, being an operationally critical limitation in high-stakes political contexts. This work investigates conditional, uncertainty-aware political deepfake detection using stochastic convolutional neural networks within an empirical, decision-oriented reliability framework. Rather than treating uncertainty as a purely Bayesian construct, it is evaluated through observable criteria, including calibration quality, proper scoring rules, and its alignment with prediction errors under both global and confidence-conditioned analyses. A politically focused binary image dataset is constructed via deterministic metadata filtering from a large public real-synthetic corpus. Two pretrained CNN backbones (ResNet-18 and EfficientNet-B4) are fully fine-tuned for classification. Deterministic inference is compared with single-pass stochastic prediction, Monte Carlo dropout with multiple forward passes, temperature scaling, and ensemble-based uncertainty surrogates. Evaluation reports ROC-AUC, thresholded confusion matrices, calibration metrics, and generator-disjoint out-of-distribution performance. Results demonstrate that calibrated probabilistic outputs and uncertainty estimates enable risk-aware moderation policies. A systematic confidence-band analysis further clarifies when uncertainty provides operational value beyond predicted confidence, delineating both the benefits and limitations of uncertainty-aware deepfake detection in political settings.
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