Abstract
Emotions are characterized by synchronized changes in several components of an organism. Among them, physiological variations provide energy support for the expression of approach/avoid action tendencies induced by relevant stimuli, while self-reported subjective pleasantness feelings integrate all other emotional components and are plastic. Consequently, emotional responses evoked by odors should be highly differentiated when they are linked to different functions of olfaction (e.g., avoiding environmental hazards). As this differentiation has been observed for contrasted odors (very pleasant or unpleasant), we questioned whether subjective and physiological emotional response indicators could still disentangle subtle affective variations when no clear functional distinction is made (mildly pleasant or unpleasant fragrances). Here, we compared the sensitivity of behavioral and physiological [respiration, skin conductance, facial electromyography (EMG), and heart rate] indicators in differentiating odor-elicited emotions in two situations: when a wide range of odor families was presented (e.g., fruity, animal), covering different functional meanings; or in response to a restricted range of products in one particular family (fragrances). Results show clear differences in physiological indicators to odors that display a wide range of reported pleasantness, but these differences almost entirely vanish when fragrances are used even though their subjective pleasantness still differed. Taken together, these results provide valuable information concerning the ability of classic verbal and psychophysiological measures to investigate subtle differences in emotional reactions to a restricted range of similar olfactory stimuli.
Highlights
Olfaction stands out in the sensory landscape for its peculiar and intimate connection with the world of emotions, which may stem from the distinctive anatomical overlap between olfactoryand emotion-related neural structures (Carmichael et al, 1994; Smeets and Dalton, 2002; Anderson et al, 2003; Grabenhorst et al, 2007; Zelano et al, 2007)
Extensive experimental evidence shows that olfactory stimulations induce differential responses at the physiological level according to their pleasantness, readily affecting heart rate, which has been shown to decrease as a function of odor hedonicity (Alaoui-Ismaïli et al, 1997; Bensafi et al, 2002b; Delplanque et al, 2009), while other indicators such as skin conductance and pupillary light reflex are sensitive to arousal (Bensafi et al, 2002b; Bradley et al, 2008; Sequeira et al, 2009)
The analysis performed on hedonicity, familiarity, and intensity ratings revealed a main effect of pleasantness on these three indicators [F(1,35) = 839.03, p < 0.001, η2s = 0.96; F(1,35) = 77.98 p < 0.001, η2 = 0.69; and F(1,35) = 7.28, p = 0.011, η2 = 0.17, respectively]
Summary
Olfaction stands out in the sensory landscape for its peculiar and intimate connection with the world of emotions, which may stem from the distinctive anatomical overlap between olfactoryand emotion-related neural structures (Carmichael et al, 1994; Smeets and Dalton, 2002; Anderson et al, 2003; Grabenhorst et al, 2007; Zelano et al, 2007). Extensive experimental evidence shows that olfactory stimulations induce differential responses at the physiological level according to their pleasantness, readily affecting heart rate, which has been shown to decrease as a function of odor hedonicity (Alaoui-Ismaïli et al, 1997; Bensafi et al, 2002b; Delplanque et al, 2009), while other indicators such as skin conductance and pupillary light reflex are sensitive to arousal (Bensafi et al, 2002b; Bradley et al, 2008; Sequeira et al, 2009). Facial muscles responsible for frowning (corrugator) and for smiling (zygomaticus) respond differentially to pleasant and unpleasant odors (e.g., Bensafi et al, 2002c; Soussignan et al, 2005; Armstrong et al, 2007; Delplanque et al, 2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
