The Scent of Emotion: A Pilot Study on Olfactory Perception Beyond Visual Cues

From an evolutionary perspective, smell and taste are the oldest human senses. Despite this, other than chemical senses—particularly vision—are commonly regarded as the most powerful tools for interacting with our environment. Within such a frame, it has become a common belief that blind individuals, especially those who are congenitally blind, develop a compensatory sensory pattern, enhancing the power of their sense of smell. However, the literature results are unclear, mainly due to the heterogeneity of the study population and of the investigation methods. Emotional reactions to olfactory stimuli in blind individuals remain underexplored, primarily due to challenges in delivering stimuli in a standardized and unbiased manner suitable for quantitative assessment. In such a framework, the present pilot study sought to indirectly discover the emotional responses of blind individuals to a specific class of sensory stimuli through the application of wearable sensors for capturing electrocardiographic (ECG) signals and galvanic skin response (GSR). Tonic GSR varied in blind individuals (p < 0.001), but not in controls. Notably, variations were observed between Baseline and Odor 1 (p = 0.002), Odors 1 and 2 (p = 0.003), Odors 2 and 3 (p = 0.003), and on the GSR phasic peak between Baseline and Odor 1 (p = 0.001). No differences were observed for ECG; however, blind individuals’ heart rate correlated with reported pleasantness (r = 0.436, p = 0.005). In light of the different patterns retrieved across stimulus responses, particularly in the GSR signal features, the comparison with a group of non-visually impaired peers shed light on the peculiarities in the psychophysiological responses of blind individuals, with potential use for tailored treatments for the improvement of well-being or, in some cases, for practical applications fostering social inclusion for affected subjects.