The Effect of Color on Flavor Perception
Joseph Puchala, Amy Humphrey, Laura Runyan, and Travis Williams
Human beings depend on their five senses to alert themselves of the world and to allow interaction with the sources of the sensed inputs. However during the transmission and integration of senses the perception of the sense can be altered. The purpose of this experiment is to explore the affects of visual interference with the perception of taste. Subjects in this experiment will be given vanilla flavored yogurt colored in a contradictory fashion to determine if the visual cues affect the interpretation of taste. This experiment also investigates whether not previous color and taste preferences affect signal interpretation and if gender and age also have a role.
Taste in humans is facilitated by modified epithelial cells organized into taste buds, located in areas of the tongue and mouth. There are five scientifically recognized taste perceptions – sweet, salty, sour, bitter, and umami (Japanese for “delicious”) – which when combined in different ratios create the diversity of flavor present in today’s world. Transduction, the transformation of stimulus energy into a change in the membrane potential of a sensory receptor, in taste cells works by chemoreceptors detecting changing gradients of certain substances. For example, a taste bud that detects saltiness has channels for Na+ to diffuse across and depolarize the cell causing signal transmission (Campbell 1055).
There is a strong correlation between tastes and color. In fact “Flavor perception arises from the central integration of peripherally distinct sensory inputs (taste, smell, texture, temperature, sight, and even sound of foods)” (Small). “One of the best examples of such an integrative process may be flavor perception, whereby activation in two peripherally distinct neural systems, olfaction and gustation, combines to give rise to a unified oral sensation” (Dalton), thus proving that flavor perception begins in the brain. Different manufacturers often make the flavors the same colors for different foods because that is what the mass majority of people recognize them as; for instance cherry is red, lemon or banana is yellow, peach is a light orange, etc. This study, which is to take place on the main campus of Miami University Oxford, is to figure out how strong the tie between color and taste is, using yogurt, by giving subjects a yogurt whose flavor doesn't correspond with its color. Our hypothesis is that the correlation will be strong enough that people will believe that the flavor of the yogurt corresponds with its color, even though it won't. Past research has concluded that our senses impact our memory and thus our behavior (Hughes). The initial question was, "What effect does color have on human perception of taste?" Since color and taste also correlate in nature, i.e. lemons are actually yellow and peaches are orange, it's likely that the association between flavor and the color of the yogurt will be even stronger than if it were just a societal rule that strawberry flavored foods are red. The interest in this study lies in, should our hypothesis be proven correct, the effect one sense has on another, when it is assumed that we, as humans, experience what is perceived through only one sense, in this case taste. Figuring out whether our mind can override our senses to tell us that we taste something we are not tasting would be an interesting aspect of human consciousness and study. How people react with their senses in an environment is of great interest to scientists, which senses hold more power over an individual's perception of the world would give interesting insight into how the brain works.
The relevance of this project has become more prominent in modern times, although the practice of dying food has been active since as long ago as 400 BC (Downham). Dye in food has taken on a variety of meanings to consumers, from added nutrition to easy flavor recognition to an appeal for children. In the advertising and product placement market, different audiences are targeted with different types of colored food; for example, the production of green and purple ketchup for kids. Kids will ask their parents to buy the colored ketchup instead of regular ketchup even though it tastes the same and is more expensive (Begun). Because it's not red, it's “cooler.” Regular vanilla ice cream is dyed red, yellow, and blue and marketed as being "Superman Ice Cream." Yellow Little Debbie cakes with vanilla flavored frosting will sport new colors and designs during holiday seasons like Halloween, Christmas, and Valentine's Day. Do people perceive these products as tasting different? Much basic food recognition is completely related to color. If a person saw a smooth, reddish-orange soup, they would probably assume it was tomato soup for this reason. The soda industry bases many of their advertising campaigns on color. When Coca Cola came out with clear Coke a few years back, it was a large failure. Many consumers said it "wasn't as good." The only thing that had been removed was the caramel-colored dye. It is possible that simply knowing it wasn't brown like regular Coke altered the consumers' perception of the taste, and that had they taste tested the two blindfolded, they wouldn't have been able to tell the difference. People often tell their drinks apart or keep track of unlabeled stored drinks according to their color, and most of our drinks are artificially colored. It is common to assume that a yellow or green colored drink is lemon-lime or citrus flavored, and that an orange drink is orange flavored. Would people be disgusted by a coke-flavored drink that was orange? Would they believe that they perceived some orange flavor in the drink just because of its color? This experiment is completely relevant, not only to human studies, but to a massive part of the food marketing industry.
Vanilla yogurt will be the key ingredient for this experiment. This yogurt will be divided into four batches. An unchanged batch of yogurt will be the control. The three other batches will be made into the variables for the experiment by adding yellow, red, and blue food dye to each. The yogurt will be served in portions of approximately 3 tablespoons in small, unmarked paper cups. Each subject will be given a clean plastic spoon to eat the yogurt. All subjects will be asked of any food allergies before testing.
The study area for the experiment will be the Miami University campus at Oxford, OH. Testing will be done more specifically within the Harrison Dining Hall lobby, a heavily trafficked area. The lab set-up will involve a table with yogurt manned by two researchers who will pass out yogurt and question subjects. Around fifty subjects will be tested for each variable and control. The other two researchers will act as advertisers and will woo potential subjects to the testing area.
A subject that wishes to take part in the test will be escorted to the table. First the researchers will ask about food allergies. Next a researcher will hand him or her a yogurt sample and a questionnaire (see figure 2.1). After the subject has eaten the sample, the subject will be asked what flavor he or she believes the sample to be. Data collected will be sorted into three different categories. The first category is subjects who guess the flavor correctly despite misleading visual cues. The next category is subjects who guess a flavor that matches the color of the visual cue (banana flavor would be an example for the color yellow). The third category is subjects who guess the flavor incorrectly and guess a flavor that is not related to the visual cue provided by the food dye (see figure 1.1 for example of possible data). Data for this project will be analyzed by using a statistical test called a chi-square test to test if the differences in distribution are significant.
Flavor Perceived by Subjects (sample data chart)
Control Yellow Red Blue
Number who guessed the flavor correctly 60 45 30 35
Number who guessed the flavor incorrectly but guessed a flavor related with dye color 25 50 60 50
Number who guessed the flavor incorrectly and guessed a flavor unrelated to dye color 15 5 10 15
This experiment requires a large number of subjects. However, the Natural Systems I class cannot volunteer to help because this experiment requires that the subjects be blind to the procedure. To compensate for the need of many subjects the researchers will test on four separate days in a period of two to three weeks depending on the weather. A complete list of the projected timeline of the project can be found below (figure 1.2).
Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Week 15
Obtain Testing Permission
Create Controls and Variables
Variable 1 Test
Variable 2 Test
Variable 3 Test
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