專(zhuān)四晨讀美文：Do Junk Food Taxes Work

Do Junk Food Taxes Work?
Public health officials grappling with the obesity epidemic
have debated a wide range of approaches
to helping slim the American waistline.
To some degree, everything from building more sidewalks
to banning chocolate milk has been explored.
Yet few tactics have been as polarizing
as the possibility of introducing tariffs on treats.
Despite endorsement
from several respected obesity researchers and politicians,
soda taxes, for example, have been subject to severe scrutiny,
as critics protested that implementing a tax
before verifying that it would achieve the end result
was shortsighted and potentially overreaching.
So, in attempt to determine
just how sin taxes might impact people's food choices,
psychologists from the University of Buffalo
decided to put junk food levies to the test-in the lab.
Researchers recruited shoppers
to examine the aisles of a mock supermarket
filled with 68 common foods
labeled with nutritional information.
Participants were given a predetermined amount of cash,
and were told to use that money to purchase
a week's worth of groceries for a family.
The first time, all of the products on the shelves
were priced in keeping with local supermarkets.
In subsequent trips, however,
junk food was taxed-an additional 12.5%, then 25%-
or healthier foods were subsidized to reduce cost.
The study, published in the journal Psychological Science,
revealed that taxes were more effective
at getting people to avoid certain products
than subsidies were at prompting healthier food purchases.
In scenarios where junk foods were taxed,
study participants generally came away
with a lower caloric total for their groceries,
and a higher ratio of protein to fats and carbohydrates.
Yet, in situations where healthy foods were subsidized,
the savings were often spent on additional junk food.
That is, instead of stocking up on more fruits and vegetables
because they were cheaper,
the study's shoppers bought their vegetables,
and then used the leftover cash
to bring home extra treats like chips and soda.
In the end, the subsidies-only scenarios resulted in
higher total calorie counts,
and didn't result in overall nutritional improvement
on the week's groceries.
Because the scenario is hypothetical,
the findings certainly shouldn't be taken
as the final word in the sin tax debate,
the researchers stress,
but should instead be used to inform the ongoing discussion
about practical ways to battle obesity.
To that end, they say,
the next step should be research to determine
whether these results would be replicated in the real world.