Abstract
BACKGROUND: Compared with unprocessed/minimally processed foods (UMPF), ultraprocessed foods (UPF) elicit stronger emotional reactions. We aimed to investigate whether octagon and/or triangle warning labels (WL) reduce the difference between the emotional reactions evoked by UPF and those evoked by UMPF. METHODS: University students (n = 247) participated in a supervised remote experiment in which normative ratings for the International Affective Pictures System (IAPS) methodology were applied. The participants were randomly allocated into three experimental study arms: (1) the barcode label (control), (2) the triangle label, and (3) the octagon label study arms. In all study arms, the participants were shown 22 food pictures (11 UPF and 11 UMPF) interspersed with 70 pictures from other affective categories in the IAPS catalog. The UPF contained one of the labels (barcode, triangle or octagon) depending on the study arm. After viewing each picture, the participants rated it according to two dimensions of emotion, namely, hedonic valence (pleasantness) and arousal. RESULTS: The participants in study arm 1 (the control group) rated UPF pictures as more pleasant and more arousing than UMPF pictures did. When UPF contained a WL (octagon or triangle label), the participants rated the UPF pictures as being equally pleasant and arousing as the UMPF pictures were. WL (triangle or octagon) can potentially reduce the greater hedonic valence and arousal evoked by UPF relative to UMPF. CONCLUSION: The current study expands the understanding of how triangle and octagon warning labels (WL) may influence consumer perceptions and behaviors. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40795-026-01296-2.