Impact of textual warnings on emotional brain responses to ultra-processed food products

Abstract

Background and objectives: Ultra-processed food products (UPF) have been associated with numerous non-communicable diseases. Despite this, the addictive nature of UPF, and the aggressive marketing strategies used to promote them, has created a strong emotional connection between UPF and consumers, and supports their increasing UPF global consumption. In view of the emotional link that consumers often have with UPF, modulating emotional reactions to UPF (by using strategies such as textual warnings) is important in changing consumers' behavior. Since emotions are better understood by assessing individuals' implicit reactions, we conducted an electroencephalographic study applying the event-related potential technique to investigate whether textual warnings were able to modulate the brain responses to UPF stimuli.

Materials and methods: Twenty-six participants (19 women) viewed pictures of UPF preceded by a warning sentence about the health risks of consuming UPF or a control sentence while the electroencephalogram was recorded. In addition, the participants rated the picture in respect of pleasantness, arousal, and intention to consume. As emotions are associated with motivational circuits in the brain, we focused on a well-known event-related potential brain marker of the motivational relevance associated with emotional stimuli, namely late positive potential (LPP).

Results: The late positive potential amplitude was larger for pictures depicting UPF under the warning condition compared to the control condition, a result that was accompanied by lower pleasantness ratings during the warning condition (compared to the control).

Conclusion: Textual warnings about the negative health consequences of consuming UPF changed the emotional responses toward UPF, possibly increasing the motivation to avoid UPF. These results shed new light on the impact of textual warnings on UPF-evoked emotions.

Keywords: EEG; consumer behavior; emotion; event-related potentials (ERP); food labeling; late positive potential (LPP); motivation; ultra-processed food.

FIGURE 1

(A) The event-related potential waveform late positive potential (LPP) was extracted from the raw electroencephalographic signal. The event of interest (UPF picture) was presented to the participant on a computer screen while the electroencephalographic (EEG) signal was being recorded. Event-markers (i.e., triggers) in the EEG signal time-locked to the UPF picture onset defined the segments from the EEG signal to be analyzed. After conducting 32 trials containing different UPF pictures, the EEG signal was averaged across the segments, revealing the event-related potential waveform–late positive potential (LPP). (B) Experimental design showing the sequence of events during the experiment. Participants viewed pictures depicting UPF preceded by a control text (the first block comprising 32 trials, control condition) or a warning text (the second block comprising the 32 remaining trials, warning condition). After viewing the UPF picture, participants rated it in two basic dimensions of emotion: arousal and pleasantness. They also rated their intention to consume the foods depicted in the pictures. UPF, ultra-processed food; EEG, electroencephalographic; LPP, late positive potential.

FIGURE 2

(A) Grand averages showing event-related potential waveforms during the warning (red line) and control conditions (blue line) across posterior electrodes (C3, Cz, C4, P3, Pz, P4, O1, Oz, O2). The grand-average ERP plots included the segment during 200 ms pre-UPF picture onset (baseline period) to a 1000 ms post-UPF picture onset. Positive voltages are plotted upward. (B) Topographical maps of the scalp (3D head, posterior view) showing the voltage distribution across the posterior electrodes during the warning (left) and control (right) conditions in the time window of 400–800 ms after UPF picture onset. The colormap changes from blue to red, the more positive-going are the waveform deflections over the scalp, measured in micro voltages (μV). Since the LPP is a waveform with positive deflection, it can be observed that it is greater during the warning condition (warm color) than during the control condition. LPP was observed at the posterior electrodes, in agreement with the literature (25). (C) Bar chart showing LPP amplitudes during the 400–800 ms time window analysis in the posterior electrodes (voltages were averaged across electrodes) in warning condition (red bar) and control condition (blue bar). *p < 0.05.