Researchers have developed a method to detect when wearable devices for stress classification are not working correctly. They found that even if the device has strong average performance, it can fail completely for an individual due to 'structural ambiguity'. This occurs when physiological channels form patterns that are not supported by the person's non-stress reference. The team introduced a pre-inference monitor called ICCM, which quantifies subject-specific coupling divergence and routes each window to classify, defer, or abstain without retraining the downstream classifier. --- Why it matters: This matters because wearable stress classifiers can have strong average performance but fail for specific individuals, leading to inaccurate results. The proposed method provides a way to detect and mitigate this issue, potentially improving the safety and reliability of these devices. Source: https://arxiv.org/abs/2608.18397