Study overview
An online tool was developed to investigate the perceived portion size norm of commonly consumed discretionary foods in Australia. Image-series of 15 discretionary foods showing different portion sizes was validated against identical real food portion size options. Using a within-person crossover design, participants attended an in-person laboratory session to complete the validation study. During the session, participants were requested to select what they perceive to be their portion size norm for each test food twice; once based on food images on the computer screen, and the other time based on equivalent real food options displayed at the food stations. The order of completion of each method and the presentation order of test foods were randomised.