Fig. 2: Suggestion-based placebo effect on the valuation stage of dietary decision-making.
From: Mapping expectancy-based appetitive placebo effects onto the brain in women
Behavioral placebo effect on: a food valuation across all trials and b food valuation split down into low and high calorie food choice trials. All boxplots display the 95% confidence intervals of the stimulus values (i.e., How much do you want to eat this food? given on a 4-point Likert scale) assigned to food during the dietary decision-making task for all three groups (n = 255 participants). Boxes correspond to the interquartile range from Q1 25th percentile to Q3 75th percentile. The gray and black lines indicate medians and whiskers range from minimum to maximum values and span 1.5 times the interquartile range. The dots correspond to individual participants. Light red corresponds to the decreased hunger suggestion group, gray to the control group, and blue to the increased hunger suggestion group. *p < 0.05, **p < 0.01. P-values were obtained with two-sampled, two-tailed t-tests between groups, and exact p-values are provided in the source data file. c Neural placebo effect on food valuation in n = 57 participants. Statistical parametric maps (SPMs) display the contrast in brain activation between the increased versus decreased hunger suggestion group in response to the stimulus value at the time of the food choice. The significant voxels in yellow are corrected for multiple comparisons using family-wise error correction on voxel and cluster level (pFWE < 0.05) and are superimposed on the average anatomical brain image. d Peri-stimulus time histograms (psth) extracted from the ventromedial prefrontal cortex global maximum of activation in response to the stimulus value for each suggestion group with shadings corresponding to the standard errors of the mean. Light red – decreased hunger suggestion group, blue –increased hunger suggestion group. Note, the psth line graphs are an illustration of the activations shown in the SPM of (c). The coordinates correspond to the Montreal-Neurological-Institute (MNI) coordinates. Source data are provided as a Source Data file.
