What is galvanic skin response?

Galvanic Skin Response (GSR): Physiological Mechanism and Applications

Galvanic skin response (GSR) is a biomarker that measures changes in electrical conductivity of the skin due to variations in sweat gland activity, reflecting autonomic nervous system arousal in response to emotional, cognitive, or physical stimuli. 1

Physiological Mechanism

• Definition: GSR (also known as electrodermal activity or EDA) refers to changes in sweat gland activity that reflect the intensity of emotional arousal 2

• Physiological basis:

  • Controlled by the sympathetic branch of the autonomic nervous system
  • Measured as either skin conductance level (SCL) - tonic/baseline activity or skin conductance responses (SCR) - phasic/event-related changes 3
  • Occurs due to activation of eccrine sweat glands, which increase moisture on the skin surface, thereby increasing electrical conductivity

• Measurement parameters:

  • Typically recorded using electrodes placed on skin surfaces with high eccrine sweat gland density
  • Common measurement sites include fingers, palms, wrists, and feet 4
  • Measured in units of microsiemens (μS) or micromhos (μmho)

Measurement Methods

• Electrode placement:

  • Most reliable measurement locations: left fingers and inner side of the right foot 4
  • Wrist measurements (both left and right) show moderate correlation with finger measurements
  • Research indicates the foot may be a suitable alternative location for homogeneous GSR measurement across test groups 4

• Sensor technologies:

  • Traditional: Metal electrodes with conductive gel
  • Modern wearable options: Flexible conductive foam sensors (correlation of 0.768 with reference GSR measurements) 5
  • Commercial devices: Shimmer3GSR, Empatica E4, and other wearable sensors 4

Clinical and Research Applications

• Stress assessment:

  • Objective indicator of autonomic nervous system arousal in response to stressors 2
  • Used in psychosomatic medicine to measure stress impact on physiological functions

• Psychiatric applications:

  • Diagnostic tool for various mental disorders 3
  • Biofeedback training method for emotional regulation
  • Neurorehabilitation supplement for comprehensive treatment of mental disorders

• Physiological monitoring:

  • Component in multisensing devices that combine heart rate, heat flux, and GSR 1
  • Used in cardiovascular monitoring technology as part of integrated systems 1

• Fear conditioning research:

  • Used to study fear-induced responses, sometimes with greater predictive validity than heart period responses 1
  • Shows distinct patterns during fear acquisition that normalize during extinction 1

• Emotion detection:

  • Helps distinguish between different emotional states
  • Used in developing emotion detection systems based on physiological responses 4

Response Patterns and Interpretation

• Typical response pattern:

  • Increased skin conductance (rise in amplitude) during cognitive or emotional arousal 6
  • Individual variation exists - some subjects (approximately 30% in one study) may not show significant GSR changes despite other physiological indicators of arousal 6

• Factors affecting response:

  • Environmental conditions (temperature, humidity)
  • Individual differences in sweat gland density and activity
  • Medications that affect autonomic nervous system function
  • Co-factors like physical activity and hydration status

Practical Applications

• Biofeedback training:

  • Allows individuals to gain voluntary control over autonomic responses 2
  • Particularly useful in pediatric practice and stress management

• Clinical monitoring:

  • Used in conjunction with other physiological measures for comprehensive assessment
  • Particularly valuable when continuous monitoring is required

• Research tool:

  • Used in laboratory settings to objectively measure emotional and cognitive responses
  • Valuable for studying fear conditioning, stress responses, and emotional processing

• Wearable technology:

  • Integration into devices for daily physiological monitoring 5
  • Applications in healthcare, emotion detection, and stress management

GSR provides a non-invasive window into autonomic nervous system activity, making it a valuable tool for both clinical assessment and research applications across multiple disciplines including psychiatry, psychology, and neuroscience.