It is now well established in psychology that a significant part of human behaviours and decision-making is influenced by unconscious processes. Eating behaviours do not escape to this rule. The aim of this thesis consisted in adapting and using methodologies and advances from cognitive psychology in order to study eating behaviours. To this end, a priming paradigm was used. This paradigm is based on the fact that the perception of a stimulus (the prime), whether it is consciously or unconsciously perceived, may modify the processing of another stimulus (the target), and have an impact on a subsequent behaviour. Evolutionarily and functionally closely related to food, olfaction represents a modality particularly interesting to study implicit priming effects on eating behaviours. Four studies have been carried out to study the effects of food odours on food choices and intake. For the first time, scientific evidences have been provided to reveal: (1) that non-consciously perceived fruity odours can impact intentions of choices and choices in a real situation of consumption in ‘healthy’ adults, guiding them toward more fruit and vegetables; (2) that an odour of cooked-meat, diffused before lunchtime, would seem to be able to increase the intake of the main course, in elderly people with Alzheimer's disease. Taken together, these results support the idea that the use of (olfactory) food primes would lead to priming effects ‘specific to the food cue’
