The galvanic skin response, measured by a specific device, is a test used to assess an individual’s skin conductivity in response to various stimuli. Generally, calm, relaxed skin sweats less, resulting in low conductivity. An increased galvanic response indicates heightened conductivity, thus revealing a state of nervousness, anxiety, or stress in the person being tested. This test is widely known for its use in lie detection. In marketing, the galvanic skin response can be used to assess the emotional arousal of individuals exposed to different advertisements. While some practitioners and researchers have reservations about its results, studies, such as those conducted by Priscilla LaBarbera and Joel Tucciarone, suggest that it can be a reliable indicator for predicting consumer reactions. Indeed, by evaluating complex communication elements such as direct marketing kits, the GSR method makes it possible to analyze the motivating effect of each individual component (such as the envelope, the letter, the brochure, the reply card, etc.) in order to identify strengths and weaknesses and make relevant adjustments.