Autonomic Regulation of Facial Temperature during Stress: A Cross-Mapping Analysis

Area of Science:

• Psychophysiology
• Biomedical Engineering
• Nonlinear Dynamics

Background:

• Skin temperature is a physiological indicator of the Autonomic Nervous System (ANS) response to emotions and mental states.
• Infrared thermography offers a non-invasive method for remote skin temperature measurement.
• Understanding facial temperature variations is crucial for accurate emotional inference using thermal imaging.

Purpose of the Study:

• To investigate the nonlinear coupling between facial temperature and ANS activity.
• To determine how stress affects facial temperature dynamics.
• To identify specific facial regions with stronger correlations to ANS correlates.

Main Methods:

• Recorded thermal images from 30 volunteers at rest and during acute stress (Stroop test).
• Measured heart rate variability (HRV) and electrodermal activity (EDA) as ANS correlates.
• Applied Cross Mapping (CM) to quantify nonlinear coupling between facial temperature and ANS time series.

Main Results:

• Facial temperature showed statistically significant nonlinear correlations with HRV and EDA, not evident in linear analysis.
• The nose exhibited a stronger link to EDA (both conditions) and HRV (under stress) compared to other facial regions.
• Cardiovascular activity was identified as a primary driver of decreased nose temperature, with gender-specific variations in coupling.

Conclusions:

• Nonlinear coupling analysis (CM) effectively reveals relationships between facial temperature and ANS activity.
• The nose is a key facial region for monitoring ANS-driven temperature changes, especially under stress.
• Findings contribute to improving emotional state detection through thermal imaging, considering gender differences.