Introduction. Nudge interventions have proven effective in supporting healthier eating, yet their application in vending machines remains limited, with few studies exploring the underlying emotional and cognitive mechanisms behind these effects.
Purpose. This research aimed to examine how visual and olfactory nudges, individually and in combination, influence healthier snack choices and related cognitive and emotional consumer responses.
Method. Two complementary studies were carried out. In a first laboratory experiment, participants interacted with a vending machine under different nudge conditions: a neutral baseline, a visual nudge (nature-themed image), an olfactory nudge (jasmine scent), or a combined condition. During the task, we assessed snack choices (behavioral), emotional and cognitive responses (skin conductance and electroencephalography), and visual attention (eye-tracking). A second field study took place in a real university setting, where the interventions were tested again across three conditions: neutral baseline, visual nudge, and olfactory nudge.
Results. In the lab, visual and olfactory nudges independently significantly increased healthy choices, while their combination did not enhance the effect. Skin conductance suggested a relaxation effect underlying the olfactory and combined nudge interventions, EEG revealed reduced approach in the combined condition, and eye-tracking showed greater attention to snacks placed at eye level. In the field, sales data demonstrated that the olfactory nudge significantly increased healthy snack purchases compared with both neutral and visual weeks, confirming its effectiveness in a naturalistic context.
Conclusions. These findings indicate that visual and olfactory nudges can promote healthier vending choices, through their combined use may reduce impact, with olfactory cues confirming the strongest effect even in real contexts. Overall, the studies highlight the emotional, cognitive, and attentional mechanisms driving consumer responses to nudges and provide practical strategies for supporting healthier eating in everyday environments while using simple sensory cues.