Effects of an open-label placebo on visual attention directed to food high in sugar, appetite, and desire for sweet taste.

Background: Interventions with deceptive placebos can reduce visual attention directed to high-calorie sweets. Open-label placebos (OLPs), which avoid the ethical concerns associated with deception, have shown promise in various fields. This is the first study to test the effects of OLPs on appetite, desire for sweet taste and visual attention for high-sugar foods.

Methods: In this preregistered laboratory study, fifty-three females (mean age = 22.8 years) were presented with image pairs depicting food high vs. low in sugar as well as non-food items. The image presentation was conducted once with and without an OLP. Different indicators of visual attention (total fixation duration, number of fixations, first fixation location), general appetite and the desire to eat the depicted food items were assessed. Moreover, participants tasted and evaluated a sucrose solution to determine their desire for the sweet taste.

Results: The OLP decreased general appetite (p = .005, η_p² = .09) and the desire to taste the sucrose solution again (p = .036, d = .30). The intervention did not affect visual attention: both conditions (with/without OLP) were characterized by a longer total fixation duration and a higher number of fixations for images with low-sugar food compared to high-sugar food when presented alongside images of non-food.

Conclusion: The OLP did not reduce visual attention toward images of high-sugar food, and OLP effects were only observed in self-report measures. Future research should elaborate on how the efficacy of OLPs can be improved or whether deception is necessary to decrease visual attention via placebos.