We talk about the five senses, but the actual boundaries aren't as clear as that offhand description implies. One recent study suggests that looking at pictures of high-calorie foods like pizza improves our perception of how pleasant anything we subsequently eat tastes.
Scientists (including some from the Nestlé Research Center, presumably a cousin of the infamous Ponds Institute) used neural imaging techniques to determine how 14 male subjects aged between 22 and 30 reacted to tastes:
Using electrical neuroimaging, we assessed whether high- and low-calorie food cues differentially influence the brain processing and perception of a subsequent neutral electric taste. When viewing high-calorie food images, participants reported the subsequent taste to be more pleasant than when low-calorie food images preceded the identical taste.
While the research sample wasn't large, the testing mechanism is fairly sophisticated, and the use of an electric taste stimulus eliminates individual reactions to familiar tastes.
The practical lesson? The way your food looks is an important part of enjoying it (a point we also visited during the Lifehacker Mastercheap experiment. If it looks good, it will taste better.