Future robots could detect how you’re feeling by touching your skin.
In a new study, scientists used skin conductivity — a measure of how well skin conducts electricity — to assess the emotions of 33 participants who were shown emotionally provocative videos.
Since skin conductivity changes when you sweat, they found a correlation between these measurements and videos that revealed feelings of fear, surprise and “family bonding emotions,” making skin conductivity an accurate way to detect changes in emotion in real time.
When used in conjunction with other physiological signals such as heart rate monitoring and brain activity, skin conductivity could play a central role in the development of emotionally intelligent devices and services, the scientists reported in a paper published Oct. 15 in the journal IEEE Access.
“To date, few studies have investigated how the dynamics of skin conductance responses differ between emotions, despite high reactivity being a key feature of skin conductance,” the scientists said in the study. “The results of this study are expected to contribute to the development of technologies that can be used to accurately predict emotions when combined with other physiological signals.”
While the study did not specifically explore integrating the technology with robotics, systems that respond to human emotions have many promising applications. These could, theoretically, include smart devices that play soothing music when you’re stressed or streaming platforms that tailor content recommendations to your mood.
To be effective, however, these devices must accurately detect and interpret emotions. In the paper, the scientists noted that common emotion-recognition technologies rely on facial recognition and speech analysis. These technologies not only tend to be unreliable — especially when video and audio signals are unclear — but also have inherent privacy concerns, the team said.
According to the study, skin conductivity may provide a solution. When humans experience an emotional response, their sweat glands are activated, which changes the electrical properties of their skin. These changes occur within one to three seconds, providing very fast feedback on a person’s emotional state.
For the study, scientists at Tokyo Metropolitan University attached probes to the fingertips of 33 participants and showed them a number of emotionally charged clips, including horror movie scenes, comedy sketches and family reunion videos. As they watched, the team measured how quickly the participants’ skin conductivity peaked and how long it took to return to normal.
The study revealed different patterns for different emotions. Fear responses lasted the longest, which the scientists explained is likely an evolutionary trait that keeps humans alert to danger. Feelings of familial bonding, described as a mix of happiness and sadness, caused slower responses, which they said may be because the two emotions interfere with each other.
The study showed that humor triggered the strongest responses, but they faded quickly. The reason for this was not immediately clear, but the scientists noted that “the literature on skin conductance dynamics in response to humor and fear” is scant.
The researchers said that while the method is not perfect, combining skin conductance with other physiological signals — such as heart rate, electromyography and brain activity — could improve the technique’s accuracy.
“There is a growing demand for technologies to infer individuals’ subjective experiences based on their physiological signals, in order to provide them with emotionally stimulating services,” the scientists wrote in the study. “Therefore, further exploration of these physiological signals, particularly skin conductance responses in this study, could advance technologies for emotion recognition.”