1. A system configured to identify atypical behavior, comprising: an eye tracker configured to perform tracking of a user's gaze while viewing items; an inward-facing head-mounted thermal camera (CAM) configured to take thermal measurements of a region of interest on the face (TH ROI ) of the user; and a computer configured to: generate feature values based on TH ROI and the tracking; and utilize a machine learning-based model to identify atypical behavior of the user based on the feature values; wherein the machine learning-based model was trained based on previous tracking and previous TH ROI of the user, taken while viewing other items.