Figure 1. Analytical pipeline for the study. Continuous
76-dimensional ARKit facial-motion data were recorded at 60fps across seven
participants expressing nine emotion categories. Three primary analytical streams
were applied to the same dataset: supervised temporal modelling using a
BiLSTM+Attention classifier, participant-specific manifold analysis using UMAP
trajectory geometry and velocity-field methods, and supervised frame-level analysis
using Linear Discriminant Analysis (LDA) and linear classification. Findings were
then subjected to cross-participant audit through shared-embedding reconstruction,
PCA-normalised trajectory comparison, and leave-one-subject-out classification.
Convergent evidence across geometry, dynamics, classification, phenomenology, and
audit supports the central claim of the paper: emotion categories remain identifiable
within individuals, but their geometric organisation is participant-specific.