Lines, dashed lines and “scale” ex-tricks. Objective measurements of appetite versus subjective tests of intake

Investigators of appetite for food have been tricked into the twin illusions that ratings of the disposition to eat are subjective and amounts eaten at meals are objective. The reality is the opposite. Making a mark on a continuous or broken line specified by two levels of what the rater uses as a single concept is the objective performance of a quantitative judgment. In contrast, the amount of a test meal that a person eats is a completely subjective outcome accumulated from many choices of another mouthful, each subject to several rapidly changing influences. Hence, rather than intake at test meals providing any validation for ratings of appetite, measurements of effects on the judged disposition to eat available food at each moment during a meal are needed to explain the amount consumed. This short paper is written in the hope of exorcising such self-deception from the research community and restoring systematic ratings of appetite to the uses for which they were introduced 35 years ago.