Derivation and development of the MacroPics food picture set

Recent research suggests that the macronutrient composition of foods can influence reinforcement independent of energy density. To further investigate this phenomenon, we developed “MacroPics,” a food picture set depicting processed American snack foods in which items contain: (1) predominantly carbohydrate, (2) predominantly fat, or (3) roughly equal proportions of carbohydrate and fat. We first photographed 60, 120-kcal portions of snack foods falling into one of the three macronutrient categories and asked 61 individuals to rate the images for liking, familiarity, frequency of consumption, healthiness, estimated energy content (in kcal) and expected satiation. A 36-item subset was then selected in an iterative process to minimize differences between the macronutrient categories on these ratings while simultaneously ensuring similar variability within category on a number of food characteristics (e.g., energy density, portion size, retail price) and visual properties (e.g., color and complexity). Item and macronutrient category characteristics of the final MacroPics set are reported.