Re: Does sight affect taste, and how would it affect it?

Hi Melissa!

This is a great question, and something that scientists have been trying to 
figure out for a while.   Your hypothesis -- that people have preconceived 
ideas about how food should look, and how it should taste -- has been 
investigated in a field of study called "taste psychophysics."  
Psychophysics is a cool branch of neuroscience that deals with people's 
perceptions.  Scientists study the pychophysics of many different sensory 
modalities, such as vision, taste, hearing, smell, and touch.

A great summary of taste psychophysics experiments can be found at this 
page: http://faculty.washington.edu/chudler/coltaste.html

The author of this site discusses a handful of experiments like the one you 
describe, where people describe red sugar water as "sweeter" than pink sugar 
water, or redder orange drink as "less natural."  Some experiments looked at 
the effect of age on taste/color perception, others looked at people's 
ability to correctly identify flavors based on color, and still more 
experiments looked at the effect of color on the "intensity" of a given 
taste quality (like sweetness).

I also know of non-laboratory experiments, where people have dyed a steak 
green and asked guests at a dinner party to taste the meat.  Not 
surprisingly, most of the guests refused, even when told that the meat was 
steak of the highest quality!

Taste psychophysics is not just fun and interesting; it's also important to 
food manufacturers.  Since the color of a food determines its perceived 
flavor and appeal, the success of a food product can depend quite 
substantially on its "look."  A recent example of successful color 
manipulation of food was Heinz's introduction of green tomato ketchup.  The 
ketchup is made just like red ketchup, but green food coloring is added to 
make it appealing to little kids!  (I can't bring myself to try it, even 
though I KNOW it's just food coloring!).

So, how is the brain doing this?  There isn't a direct connection between 
the eyes and tongue.  Instead, information from the eye goes to the visual 
cortex, at the back of your head.  "Taste" is actually a mixture of 
information about the odor of a substance and its sweet/salty/sour/bitter/
umami characteristics.  (Umami is the taste of the food additive MSG, and is 
detected by special receptors on the tongue).  Odor information is conveyed 
from neurons in the nose to the olfactory bulb, at the front of your head.  
Taste information from mouth neurons is conveyed to the nucleus of the 
solitary tract, in your brainstem (at the back of your head, near where your 
hairline is).   The place where the quality and appeal of  food is 
determined is not at all clear.  In all likelihood, a variety of brain 
areas, including an area called the limbic system, are involved in deciding 
whether a food looks, tastes, and smells appealing relative to everything 
else you've eaten in the past!

A view of the visual, olfactory, and taste pathways can also be found on the 
NeuroKids site: http://faculty.washington.edu/chudler/introb.html

Hope this helps,
Amanda Kahn
amandak@phy.ucsf.edu