Spirometry and EDA as Cognitive Load Markers (Neukirchen 2022)

What was investigated?

Researchers at the University of Wuppertal investigated whether respiratory gas parameters (oxygen uptake VO2 and carbon dioxide output VCO2) are suitable for physiologically distinguishing cognitive load from emotional stress. The direct comparison pitted spirometry against electrodermal activity (skin conductance) as a psychophysiological measurement method. The central question: Which method is more sensitive to which type of stress — and do both methods complement each other?

Methods

In a within-subject design, 25–27 male participants (mean age 26.35 years) each underwent a single session with six experimental episodes: relaxation, baseline, and two experimental conditions in counterbalanced order. The cognitive task was the Corsi Block-Tapping Task (spatial working memory); the emotional stressor was the threat-of-shock paradigm (anticipation of electric shocks). Both measurement methods — spirometry and skin conductance — were applied simultaneously to the same participants under identical conditions.

Results

The researchers found clear differences in the reactivity of both measurement methods to the two stress types:

Oxygen uptake (VO2) — Spirometry: VO2 responded much more strongly to cognitive load (mean increase: 21.40%) than to emotional stress (5.69%). The difference was highly statistically significant (p < 0.001). VO2 could distinguish cognitive load from emotional stress with an area under the ROC curve (AUC) of 0.797.

Electrodermal activity (EDA) — eSense Skin Response: Skin conductance measurement showed the opposite response pattern: It responded more strongly to emotional stress than to cognitive load (p < 0.001). The researchers found a high correlation of EDA reactivity between both conditions (r = 0.70; p < 0.001), indicating lower discriminative ability between cognitive and emotional load — the strength of EDA lies in capturing emotional arousal in general, not in distinguishing between stress types.

Combined use: The researchers concluded that both methods have different strengths and complement each other. Negative correlations between VO2 reactivity and cognitive performance as well as positive correlations with shock anticipation anxiety confirmed the good external validity of both measurement approaches.

Significance

This study, published in Scientific Reports (Nature Portfolio), demonstrates that EDA and spirometry are complementary — not competing — measurement instruments. According to the study, the eSense Skin Response is particularly well suited for capturing emotional arousal and stress activation, while spirometry is more sensitive to cognitive demands.

Relevant for scientific classification: The eSense Skin Response was used in a published, peer-reviewed laboratory experiment at a German university and delivered reproducible, statistically analyzable data. The study thus represents an independent demonstration of the sensor’s suitability for psychophysiological research in the laboratory.