Skin conductance, also known as electrodermal activity (EDA), is a measurable physiological response reflecting subtle changes in the skin’s electrical properties. Researchers and clinicians use this measurement to understand the body’s automatic reactions to various stimuli and situations. This physiological indicator provides insights into an individual’s internal state, often linked to arousal levels.
Understanding Skin Conductance
Skin conductance refers to the skin’s ability to conduct electricity, which changes in response to internal and external factors. This electrical property is directly influenced by the activity of sweat glands. When these glands become more active, they produce sweat containing water and electrolytes, enhancing the skin’s electrical conductivity.
Measurement typically involves placing two electrodes on the skin, often on the palms or soles of the feet, where sweat gland density is high. A small electrical current is passed between these electrodes, and changes in how easily the current flows are recorded. These changes are commonly measured in microsiemens (µS) and reflect fluctuations in the skin’s electrical conductance.
The Body’s Underlying Mechanism
The physiological basis of skin conductance changes lies within the autonomic nervous system, specifically its sympathetic branch. This part of the nervous system regulates many involuntary bodily functions, including sweat gland activity. When activated, it stimulates eccrine sweat glands, which are highly responsive to psychological and emotional stimuli.
This activation causes these glands to secrete a watery fluid onto the skin’s surface. This increase in moisture enhances the skin’s ability to conduct electricity. Therefore, momentary changes in skin conductance serve as an indirect measure of sympathetic nervous system arousal. This response occurs automatically, reflecting the body’s readiness to react to significant events.
Interpreting the Signals
Fluctuations in skin conductance primarily signify general physiological arousal, rather than pinpointing a specific emotion. An increase indicates heightened sympathetic nervous system activity, associated with states like emotional intensity, focused attention, cognitive effort, or stress. Conversely, a decrease suggests a reduction in this physiological arousal.
These changes are largely automatic and occur without conscious control, reflecting the body’s non-volitional responses to stimuli. A novel or significant event can trigger a skin conductance response, even if the individual is not consciously aware of an emotional shift. While it reliably indicates arousal, skin conductance does not differentiate between various emotional states like happiness, fear, or anger.
Where Skin Conductance is Used
Skin conductance measurement finds diverse applications across various fields, providing objective data on physiological arousal.
Psychological Research
In psychological research, it is a tool for studying emotional responses, attention, and cognitive processes. Researchers use it to observe how individuals react to different stimuli, offering insights into their emotional engagement.
Biofeedback Therapy
Biofeedback therapy employs skin conductance to help individuals learn to regulate their physiological responses. Patients observe real-time levels to practice relaxation techniques, aiding in stress reduction, anxiety management, and conditions like epilepsy. This empowers individuals to gain greater control over their autonomic nervous system.
Lie Detection
Polygraph tests incorporate skin conductance alongside other physiological measures. Deceptive responses may elicit increased sympathetic arousal, reflected in conductivity changes. However, its use as a sole indicator of truthfulness remains controversial, as anxiety or other emotions can also produce similar physiological responses.
Consumer Research and Wearable Devices
Beyond clinical and research settings, skin conductance is utilized in consumer research to gauge emotional reactions to products, advertisements, or user experiences. This helps companies understand unconscious consumer preferences. Wearable devices increasingly incorporate skin conductance sensors for health monitoring, providing continuous data on stress levels, sleep quality, and overall well-being, offering insights into physiological states.