Anorexic and bulimic patients have a highly distorted relationship with food and eating, even though they tend to be knowledgeable about diet and nutrition. The progress of this disease, as well as its complications and associated difficulties, are increasingly understood, while the etiopathogeny of eating disorders remains obscure. The approach that we are proposing involves the study of one of the most fundamental cognitive functions of human reasoning--the cognitive process of categorization. The purpose of this study is to understand the procedures used by these patients to construct representations of food. Categorization, one of the basic features of human cognition, allows individuals to organize their subjective experience of the surrounding environment by structuring its contents. This ability to group different objects into the same category based on their common characteristics is important for explaining the major cognitive activities of planning, memorization, communication and perception. Indeed, our categories reflect our conceptions of the world. They depend on our experiences and representations, as well as the expertise acquired in a specific field. The differences that appear in the categories created by subjects when they are asked to classify objects reveal the properties that are most salient to them and, as a result, the interests, values and ideas associated with these properties. There are three types of properties: perceptive properties, which describe the object's shape, color, odor and texture; structural properties, which relate to the object's components; and functional properties, which specify the way in which the object is used and provide an answer to the question, "What is it used for?". Subjects attribute these functional properties by means of knowledge or inference according to their representation of the object's role; such properties are especially likely to emerge during top-down (theory-driven) processing. The type of processing used (bottom-up or top-down) is dependent on a certain number of factors. We hypothesize, within the context of food product categorization, that patients suffering from eating disorders largely resort to processing based on acquired information or beliefs about the objects, i.e. top-down processing. We present two studies: a naturalistic and exploratory pilot study whose goal is to identify whether the various categorization processes used by eating disorder patients differ from those employed by subjects not suffering from an eating disorder. A second study aims to identify the different categorization procedures. During the first experiment, 68 women (17 control subjects, 17 anorexics, 17 anorexic bulimics and 17 bulimics) aged 18-39 (average age: 26.6) verbalize all representations that come to mind during a limited time period as the name of a food item is read. Eighty-nine food items are presented in alphabetical order. The list is read out loud and all comments are recorded. The data is processed in three ways : an analysis based on the pos...