The effects of nonoral sensations, such as visual texture and odor, on the size of the first bite were investigated in a series of studies using specially constructed food delivery cups with lower, from which custards were ingested ("ingested custard"), and upper, from which a custard was viewed and/or smelled ("upper custard") compartments. Ingested and upper custards were either the same or different. Bite size was defined as the weight of custard sucked out of the lower compartment during a single suck through an I I -mm diameter straw. The results from the first study indicated that the recognition of oral qualities of custards via vision or olfaction determined the size of the first bite. When this recognition was favorable, e.g., when the upper custard was known to be creamy, a relatively large bite was taken, irrespective of the custard that was actually ingested. When this recognition was unfavorable, a relatively small bite was taken. The second study showed that when recognition was prevented by modifications of the upper custard's color, odor, or visual texture, bite size was determined by the oral qualities of the ingested custard. This was confirmed in a third study, where the oral characteristics of the ingested custard were varied by adding a flavorant (benzaldehyde) and/or by using nose clips to eliminate retronasal smelling. Bite sizes decreased significantly when these variations reduced creaminess. Odor and visual texture characteristics of the upper custard significantly affected the perception of creaminess and other attributes related to the food's viscosity, melting, and thickness. (C) 2004 Elsevier Inc. All rights reserved.