Appetite, 1996, 27, 119–133 Palatability and the Micro-structure of Feeding in Humans: the Appetizer Effect MARTIN R. YEOMANS Experimental Psychology, University of Sussex The eﬀects of manipulated palatability on eating were assessed in 54 human volunteers eating pasta with a tomato sauce, with palatability adjusted by the addition of three levels of oregano. Meals were divided into 2 min eating episodes separated by brief pauses during which subjects rated aspects of appetite. Both intake and eating rate were greatest in the most palatable condition (0·27% oregano), whereas the addition of 0·54% reduced intake and eating rate. Hunger ratings increased during the initial stages of the meal with 0·27% oregano, but fell throughout the meal in the other conditions, whereas fullness ratings increased similarly in all three conditions. Rated food attractiveness was greatest with 0·27% oregano, and least with 0·54% oregano, but declined similarly through the meal with all three foods. Initial ratings of palatability were similar to those for food attractiveness, but changes in palatability across meals varied between subjects. Male subjects consistently ate more and faster than females, but similar eﬀects of manipulated palatability on intake and subjective appetite were seen in both sexes. These data are consistent with the idea that palatability increases intake through a positive-feedback reward mechanism, and oﬀers a novel method for measuring these eﬀects.  1996 Academic Press Limited I  The notion of palatability is often referred to in studies of appetite, and is generally used to denote the eﬀects of the sensory qualities of foods on intake. However, the specific definition of palatability has recently been the subject of considerable debate (e.g. Ramirez, 1990). While most attempts to define palatability make explicit reference to either the hedonic properties or eﬀects of foods (e.g. Le Magnen, 1987; Young, 1967), whether palatability is better defined as an objective property of foods, an individual’s reaction to a given food under standardized conditions (Kissileﬀ, 1986), or as the immediate eﬀect of a particular food on ingestion (Booth, 1990) is open to debate. Arguably, part of the reason for the lack of agreement in defining palatability is that each of the above definitions is perfectly acceptable for each researcher within their own approach to the study of ingestive behaviour. However, having a central concept such as palatability defined op- erationally by diﬀerent researchers greatly reduces the utility of this term as a The author wishes to thank Dr Pete Clifton for his help with software development, and Cindy Cox and Jill Knudsen who helped run these studies. Correspondence to: Dr M.R. Yeomans, Laboratory of Experimental Psychology, University of Sussex, Brighton, BN1 9QG, U.K. 0195–6663/96/050119+15 $25.00/0  1996 Academic Press Limited