Research report Alliesthesia is greater for odors of fatty foods than of non-fat foods § Jane Plailly a,b,c, *, Ninhda Luangraj a , Sophie Nicklaus a , Sylvie Issanchou a , Jean-Pierre Royet b , Claire Sulmont-Rosse ´ a a Centre des Sciences du Gou ˆt et de l’Alimentation, UMR 6265 CNRS, UMR 1324 INRA, Universite ´ de Bourgogne, Agrosup Dijon, F-21000 Dijon, France b CNRS UMR5292, INSERM U1028, Universite ´ Lyon1, Lyon Neuroscience Research Center, Olfaction: from Coding to Memory Team, Lyon, F-69000, France c CNRS UMR5292, INSERM U1028, Universite ´ Lyon1, Centre de Recherche en Neurosciences de Lyon, Equipe Olfaction: du Codage a ` la Me ´moire, Lyon, F-69366, France Introduction An internal state of hunger or satiety is well-known to influence food perception. Cabanac (1971) suggested the term alliesthesia to describe the fact that a sensory stimulus can generate pleasant or unpleasant feelings depending on the internal state of the consumer. In fact, studies presenting food-related stimuli to participants have shown that the same stimulus can be perceived as either pleasant during a state of hunger (positive alliesthesia) or unpleasant during a state of satiety (negative alliesthesia) (Cabanac & Fantino, 1977; Cabanac, Minaire, & Adair, 1968; Laeng, Berridge, & Butter, 1993; Scherr & King, 1982). Alliesthesia was first studied using paradigms in which pleasantness of one or two foods was evaluated both before and after ingestion of a glucose load (Cabanac, 1971; Cabanac & Fantino, 1977) or a snack (Scherr & King, 1982). This approach presents the benefit of simulating everyday life processes concerning food pleasantness in the context of meal consumption. However, these studies evaluated a low number of foods and, because alliesthesia could be item-specific, results may be biased. One method employed to address this limitation is the use of visual items. In comparison to gustatory stimuli, visual stimuli are easier to create and manipulate and numerous pictures can be presented in the same experiment. Therefore, alliesthesia has often been explored using large sets of visual items depicting foods that were evaluated before and/or after an ad libitum lunch (Finlayson, King, & Blundell, 2007; Lozano, Crites, & Aikman, 1999; Stoeckel, Cox, Cook, & Weller, 2007). However, the best compromise between plausibility and convenience is probably reached with the use of odorous stimuli. Odors are naturally part of the signal perceived during food ingestion (Yeomans, 2006) and are thus appropriate for studying alliesthesia for food items; moreover, they are easier to use than real food. In addition, memories based on odors are more emotional than memories associated with visual, tactile, auditory or verbal items (Goddard, Pring, & Felmingham, 2005; Herz, 1998; Willander & Larsson, 2007). Odors are therefore relevant cues for studying food pleasantness and have been used in a limited number of studies about alliesthesia (Albrecht et al., 2009; Duclaux, Feisthauer, & Cabanac, 1973; Jiang et al., 2008). The small number of experiments addressing alliesthesia has given rise to a partial characterization of this phenomenon. It has been clearly demonstrated that negative alliesthesia predomi- nantly concerns food items in comparison to non-food items (Duclaux et al., 1973; Jiang et al., 2008; Stoeckel et al., 2007). The demonstration of alliesthesia-specificity has been refined in a Appetite 57 (2011) 615–622 ARTICLE INFO Article history: Received 16 December 2010 Received in revised form 6 July 2011 Accepted 11 July 2011 Available online 22 July 2011 Keywords: Alliesthesia Fat Pleasantness Appetence Odor Internal state ABSTRACT Alliesthesia is the modulation of the rewarding value of a stimulus according to the internal state (hungry or satiated). This study aimed to evaluate this phenomenon as a function of the nature of the stimulus (odors evoking edible and non-edible items, and the food odors evoking fatty and non-fat foods) and to compare the effectiveness of two reward evaluations (measures of pleasantness and appetence) to reveal alliesthesia. The results showed that both fatty and non-fat food odors were judged as less pleasant and less appetent when the subjects were satiated than when they were hungry, whereas no such difference was observed for non-food odors. There was a greater decrease in appetence than there was in pleasantness. Moreover, the decrease in appetence was greater for fatty than for non-fat food odors, whereas the decrease in pleasantness was similar for both fatty and non-fat food odors. Our study allows for the definition of a more comprehensive pattern of alliesthesia based on odor category. It demonstrates that alliesthesia is specific to food odors and that it is more pronounced when odors are associated with fatty rather than non-fat foods. It also reveals that an appetence measure is more sensitive than a pleasantness measure for describing an acute reward modulation process. ß 2011 Elsevier Ltd. All rights reserved. § This work was supported by a grant from the Institut National de la Recherche Agronomique (INRA). * Corresponding author.. E-mail address: plailly@olfac.univ-lyon1.fr (J. Plailly). Contents lists available at ScienceDirect Appetite journal homepage: www.elsevier.com/locate/appet 0195-6663/$ – see front matter ß 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.appet.2011.07.006